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Purpose: This study aimed to analyse the clinical outcomes of preoperative adjuvant denosumab therapy (PADT) combined with resection and arthrodesis for recurrent grade 3 giant cell tumor of bone (GCTB) in the distal radius., Methods: A retrospective study was conducted on twenty-three patients (8 males, 15 females) who were treated with the adjuvant denosumab combined with en bloc resection (EBR) and arthrodesis for biopsy confirmed recurrent Campanacci III giant cell tumor of bone in the distal radius between January 2015 and December 2022. All 23 patients were treated with wrist arthrodesis reconstruction using autogenous free iliac crest bone graft (ICBG), bridging plate and screws. The local control, metastasis and overall survival were evaluated during the follow-up period. Functional outcomes were evaluated using the Disabilities of the Arm, Shoulder and Hand (DASH) score, Musculoskeletal Tumor Society Score (MSTS-87 and MSTS-93), and grip strength in the follow-up period. Additionally, all surgical or denosumab-related complications that occurred were recorded in this study., Results: Twenty-three patients were included in this retrospective study and no patients were lost in the follow-up period. The average patient age was 32.5 ± 10.2 years (range, 19-53 years) and the mean follow-up time was 35.5 ± 18.4 months (range, 13-72 months). The average tumor length was 71.7 ± 8.7 mm (range, 50 to 85 mm) and bone reconstruction length was 78.5 ± 8.5 mm (range, 60 to 90 mm). Four patients (17.4%) had secondary local recurrence after reoperation and two patients had (8.7%) multiple recurrences. One patient (4.3%) was deceased in the last follow-up due to multiple metastases. The estimated 5-year recurrence-free survival rate was 81.3% and 5-year metastasis-free survival rate was 95.7%. The mean union time was 8.5 ± 1.9 (6-12) months and the overall survivorship of the allograft was 82.7% (21/23) at an average 35 month follow-up. The average MSTS-87 and MSTS-93 scores were 27.8 ± 1.6 (range, from 23 to 30) and 91.5 ± 5.0 (range, from 76 to 100), and the average DASH score was 8.9 ± 3.2 (range, from 3 to 15), respectively. The average grip strength was 64.6 ± 15.7% (range, from 30 to 95%) of the uninvolved side. Eight patients (34.7%) had at least one complication in the follow-up time. Two autografts (8.7%) were removed due to local recurrence and bone nonunion, and the average autograft survival time was 32.8 ± 18.5 months (range, 12 to 72 months)., Conclusions: Preoperative adjuvant denosumab therapy (PADT) combined with en bloc resection and arthrodesis is a promising method for the treatment of recurrent Campanacci III GCTB in distal radius with acceptable short-term local control and functional satisfaction., Level of Evidence: level IV Therapeutic., (© 2024. The Author(s).)

We present a case detailing the diagnosis and management of a periprosthetic giant cell tumour in a female patient in her 70s, who had undergone total knee arthroplasty (TKA) for primary osteoarthritis in her right knee 7 years prior. The patient reported 4 months of painful weight-bearing. Various imaging modalities, including plain radiographs, CT scans and MRI, revealed a sizeable lytic lesion beneath the TKA prosthesis, along with loosening of the tibial component.Blood tests and analyses of synovial fluid ruled out periprosthetic joint infection, and a biopsy confirmed the diagnosis of a giant cell tumour of the bone. Treatment entailed en bloc resection of the tumour and revision of the TKA using a hinged, oncological-type megaprosthesis. Surgical procedures involved careful resection of the proximal tibia, preservation of vasculature and the creation of a medial gastrocnemius muscle flap. Following surgery, the patient underwent supervised rehabilitation with a functional brace., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Giant cell tumors of bone (GCT) are rare soft tissue tumors, that account for 3%-5% of primary bone tumors with <2% occurring in the head and neck. The nasal cavity is a highly unusual site of presentation. We reviewed 15 cases of GCT of nasal cavity and paranasal sinuses. We add 1 case to the literature. The case herein reported, appears to be the second nasal fossa GCT described in the literature and the first documented case with multifocal localization. A case of multifocal GCT of the nasal cavity is described. Although rare in the general population, GCT should be included among the possibilities in the differential diagnosis when evaluating tumors of the head and neck. Management of this particular tumor remains challenging; surgical removal is still the gold standard treatment, preferring a minimally invasive trans-nasal approach to reduce intra and post-operative morbidity. Laryngoscope, 134:2774-2778, 2024., (© 2023 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

SummaryGiant cell tumours of bone are benign and locally aggressive tumours that usually occur in young adults and at the epiphysial locations after physeal closure. Occurrence outside of epiphysial locations and appearance in geriatric patients is rare. We report a case of a woman in her late 60s with a giant cell tumour of the mid-shaft of the right tibia. Extended curettage and biological reconstruction were performed with autologous double-barrel fibular struts and tri-cortical iliac crest bone grafting. At the 28-month follow-up examination, we noted full bony union at both ends with successful consolidation of the fibular struts, and importantly, no evidence of recurrence or other complications was observed., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Giant cell tumor of bone (GCTB) is a rare tumor of the bone that is locally invasive. Surgery is the primary treatment that is usually done by intralesional curettage. In pelvis and spine surgery may be associated with high rate of complications, recently, Denosumab has been proposed for the treatment of these tumors in latter anatomical regions. Denosumab may be administered alone or as an adjuvant to surgery. This study aimed to assess the treatment effects of Denosumab in patients with unresectable GCTB. This study was a case series. Patients with unresectable GCTB of vertebra and sacrum were enrolled in this study. Patients received 120 mg of monthly Denosumab and additional doses on days 8th and 15th of treatment. Images of patients before and after treatment were evaluated. Nine patients with a median age of 30 years with spine and sacrum GCTB were included in this study. The median time of treatment with denosumab was 28 months (range: 3-67). Tumor control was seen in all patients. According to Inverse Choi density/size (ICDS), criteria objective response (complete response and partial response) was seen in 8 patients, and one had stable disease. Based on CT scan images, in 4 patients (44.44%), less than 50% of the transverse diameter of the tumor became ossified, and in the other five patients (55.55%), more than 50% of the tumor's transverse diameter became ossified. The median tumor volume before treatment was 829 cm3, and after treatment was 504 cm 3 which was significantly reduced (P = 0.005). No complication related to therapy was seen. Tumor response was seen in all patients, and tumor control according to ICDS criteria was evident in all cases. This finding was in line with previous studies. Clinical improvement of signs and symptoms was also seen in all patients. Generally, our study demonstrates a sustained clinical benefit and tumor response with Denosumab, as tumor response ≥ 24 weeks was evident in all cases. No side effects were seen in patients despite long-term treatment with Denosumab., (© 2023. The Author(s), under exclusive licence to Istituto Ortopedico Rizzoli.)

Giant cell tumour (GCT) accounts for 5% of all primary bone tumours. GCT in the distal third of ulna is quite rare. We present a case of recurrent GCT in distal third of ulna with malignant features involving tenosynovium. The case was treated by wide resection of tumour and on follow up, patient recovered well with no evidence of further recurrence. Considering the features, according to the literature reviewed, is the first case of its type., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To determine the value of CT and dynamic contrast-enhanced (DCE-)MRI for monitoring denosumab therapy of giant cell tumors of bone (GCTB) by correlating it to histopathology., Materials and Methods: Patients with GCTB under denosumab treatment and monitored with CT and (DCE-)MRI (2012-2021) were retrospectively included. Imaging and (semi-)quantitative measurements were used to assess response/relapse. Tissue samples were analyzed using computerized segmentation for vascularization and number of neoplastic and giant cells. Pearson's correlation/Spearman's rank coefficient and Kruskal-Wallis tests were used to assess correlations between histopathology and radiology., Results: Six patients (28 ± 8years; five men) were evaluated. On CT, good responders showed progressive re-ossification (+7.8HU/month) and cortical remodeling (woven bone). MRI showed an SI decrease relative to muscle on T1-weighted (-0.01 A.U./month) and on fat-saturated T2-weighted sequences (-0.03 A.U./month). Time-intensity-curves evolved from a type IV with high first pass, high amplitude, and steep wash-out to a slow type II. An increase in time-to-peak (+100%) and a decrease in Ktrans (-71%) were observed. This is consistent with microscopic examination, showing a decrease of giant cells (-76%), neoplastic cells (-63%), and blood vessels (-28%). There was a strong statistical significant inverse correlation between time-to-peak and microvessel density (ρ = -0.9, p = 0.01). Significantly less neoplastic (p = 0.03) and giant cells (p = 0.04) were found with a time-intensity curve type II, compared to a type IV. Two patients showed relapse after initial good response when stopping denosumab. Inverse imaging and pathological findings were observed., Conclusion: CT and (DCE-)MRI show a good correlation with pathology and allow adequate evaluation of response to denosumab and detection of therapy failure., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Purpose: Wrist reconstruction after distal radial tumor resection poses a challenge to the orthopedic oncologist. We evaluated the functional outcomes of centralization of the ulna with ulnocarpal arthrodesis as a method of reconstruction following resection of distal radius tumors, using impairment measures and patient-reported outcomes., Methods: Evaluation of functional outcome was performed using the Musculoskeletal Tumor Society 93 scoring system and Disabilities of the Arm, Shoulder, and Hand questionnaire. We also determined hand grip strength on the affected side, time to radiologic union at the ulnocarpal junction and reduction in wrist circumference. Local complications and oncologic outcomes were recorded., Results: The study included 26 patients with Campanacci grade 3 giant cell tumor of the distal radius. Mean follow-up period in the study was 32.8 ± 12 months. Mean resection length was 10.3 ± 2.5 cm. Radiologic union at the ulnocarpal junction was achieved in 38.5%, 77% and 96% of the patients by 4, 5, and 6 months respectively. Mean hand grip strength was 74 ± 3.9% of the contralateral side whereas mean reduction in wrist circumference was 16.9 ± 6.4%. A good functional outcome with a mean the Musculoskeletal Tumor Society 93 score of 26 ± 1.4 and mean Disabilities of the Arm, Shoulder, and Hand score of 10.5 ± 6.3 was observed. Fracture of the ulna, hardware loosening, and reflex sympathetic dystrophy were each noted in 1 patient, with an overall complication rate of 10.7% (3/28). No patient had nonunion, infection, or local recurrence., Conclusions: This is a simple and effective modality of reconstruction after resection of distal radial tumors. It provides good functional outcome and preservation of good hand grip strength, with low complication rates., Type of Study/level of Evidence: Therapeutic IV., (Copyright © 2024. Published by Elsevier Inc.)

Background/aim: Giant cell tumor of bone (GCTB) is a locally aggressive neoplasm that typically occurs in the ends (epiphyses) of long bones of young adults. Flat bones are uncommon sites of involvement. Herein, we describe an unusual case of pathologically proven GCT of the acromion., Case Report: The patient was a 39-year-old woman with no history of trauma who presented with a 3-month history of right posterior shoulder pain. Physical examination revealed mild swelling and tenderness in the posterior aspect of the right shoulder. Plain radiograph showed a purely lytic lesion, suggestive of a bone tumor. Computed tomography demonstrated an intraosseous lytic lesion with associated cortical thinning and lack of periosteal reaction. On magnetic resonance imaging, the lesion exhibited slightly higher signal intensity compared to skeletal muscle on T1-weighted sequences and heterogeneous high signal intensity on T2-weighted sequences. Strong enhancement was observed following gadolinium administration. The lesion was treated by extensive curettage with adjuvant therapy comprising ethanol and the remaining cavity was filled with polymethylmethacrylate bone cement. Histologically, the lesion was composed of round or spindle-shaped mononuclear cells admixed with numerous osteoclast-like giant cells. Immunohistochemically, the mononuclear neoplastic cells were diffusely positive for H3.3 G34W. The patient was asymptomatic and there was no evidence of local recurrence or distant metastasis 5 months after surgery., Conclusion: Although rare, acromial GCTB should be considered in the differential diagnosis of posterior shoulder pain, especially in young and early middle-aged adults., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Giant cell tumour of bone is a benign, locally aggressive osteolytic tumour that typically affects skeletally mature young individuals. It predominantly emerges within the metaphysis, extending towards the epiphysis of long bones, while occurrences in flat bones are exceptionally rare. We present a case of a woman in her late 20s who presented with a large right ischial mass. A biopsy confirmed the mass as a giant cell tumour. The tumour extended to the acetabulum, and due to the potential risk of significant bleeding and contamination during en bloc excision, a prudent approach involved initiating denosumab therapy, a monoclonal antibody targeting receptor activator of nuclear factor-κB ligand therapy, before proceeding with radical surgery. Denosumab therapy successfully rendered a previously inoperable tumour favourable for surgical intervention. We went on to perform a type 2 and 3 internal hemipelvectomy, followed by a reconstruction with a hip endoprosthesis replacement., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To describe the presentation of giant cell tumors (GCT) of the bone in the pediatric population to (1) improve the differential diagnosis of pediatric bone tumors and (2) identify the origin of GCT. Understanding the origin of bone tumors assists in establishing appropriate diagnoses and recommending treatment options. This is particularly important in children, where evaluating the need for invasive procedures is balanced with the desire to avoid overtreatment. GCT have historically been considered epiphyseal lesions with potential metaphyseal extension. Therefore, GCT may be inappropriately excluded from the differential diagnosis of metaphyseal lesions in the skeletally immature., Materials and Methods: We identified 14 patients from 1981 to 2021 at a single institution who had histologic confirmation of GCT and were less than 18 years old at diagnosis. Patient characteristics, tumor location, surgical treatment, and local recurrence rates were collected., Results and Conclusions: Ten (71%) patients were female. Eleven (78.6%) were epiphysiometaphyseal (1 epiphyseal, 4 metaphyseal, 6 epiphysiometaphyseal). Five patients had an open adjacent physis, of which three (60%) had tumors confined solely to the metaphysis. Of the five patients with open physis, four (80%) developed local recurrence while only one patient (11%) with a closed physis had local recurrence (p value = 0.0023). Our results illustrate that for the skeletally immature, GCT can (and in our results more commonly did) occur in the metaphyseal location. These findings suggest that GCT should be included in the differential diagnosis of primary metaphyseal-only lesions in the skeletally immature., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Purpose: This study aimed to investigate whether short course of neoadjuvant denosumab treatment for spinal GCTB could (1) Induce radiological and histological response? (2) Facilitate en bloc resection? (3) Achieve satisfactory oncological and functional outcomes?, Methods: The clinical information of ten consecutive patients between 2018 and 2022 with spinal GCTB treated with short course of neoadjuvant denosumab (≤ 5 doses) and en bloc spondylectomy was retrospectively reviewed. The radiological and histological response, operative data, oncological and functional outcomes were analyzed., Results: The mean doses of neoadjuvant denosumab were 4.2 (range 3-5 doses). After neoadjuvant denosumab, there were 9 cases showing new ossification and 5 cases with reappearance of cortical integrity. The values of Hounsfield units (HU) of the soft tissue component were increased by > 50% in 7 cases. The signal intensity (SI) ratios of tumor/muscle in T2WI of plain MRI were decreased by > 10% in 60% of the cases. Shrinkage of soft tissue mass by > 10% was observed in 4 cases. The mean duration of operation was 575 ± 174 min, and the mean estimated blood loss (EBL) was 2790 ± 1934 ml. No obvious adhesion to dura mater or major vessels was encounter intraoperatively. There is no tumor collapse or breakage during surgery. Multinucleated giant cells were decreased in 6 cases (60%) with the remaining 4 cases showing absence of multinucleated giant cells. Mononuclear stromal cells existed in most of the cases (8 cases, 80%). New bone formation was noticed in 8 cases (80%). No patient had a worsening of neurologic function after surgery. No tumor recurrence was noticed within the mean follow-up of 24 ± 20 months., Conclusion: Short-term neoadjuvant denosumab could yield radiological and histological responses and might facilitate en bloc spondylectomy by hardening the tumor and causing less adhesion to segmental vessels, major vessels and nerve roots, which was beneficial to achieve the optimal oncological and functional outcomes., (© 2023. The Author(s).)

The typical presentation of giant cell tumor of bone is a solitary lesion involving the meta-epiphyseal region of the long bones. The presence of more than one distinct giant cell tumor in the same patient is rare. This study reports on 7 patients with multicentric giant cell tumor of bone. Clinical and radiologic features were reviewed to evaluate the behavior of multicentric giant cell tumor of bone. Immunohistochemistry and genetic analysis for the H3F3A gene were performed to confirm the diagnosis. The knee was most frequently involved, and most of the lesions were in an ipsilateral extremity. All of the patients received surgical management with curettage or resection. The overall median follow-up was 194 months (interquartile range, 41-336 months). Five of 7 patients had local recurrence (71%), but considering the number of surgically treated lesions, the risk of local recurrence was 33% (5 local recurrences among 15 treated lesions). No lung metastases occurred. Multicentric giant cell tumor of bone tends to exhibit the same aggressive clinical behavior as solitary giant cell tumor of bone. Patients should be monitored for the occurrence of other lesions, especially in the ipsilateral extremity. [ Orthopedics . 2023;46(6):e376-e380.].

Giant cell tumor (GCT) is a benign tumor that originates from undifferentiated mesenchymal cells of the bone marrow. The craniums as well as temporal bone are extremely rare locations for GCTs. Clinical, radiological, and anatomical diagnosis of this locally aggressive disease poses a major challenge in clinical practice. In this article, we present a clinical study for a 35-year-old female who was found to have left-sided temporal bone GCT with extension to middle cranial fossa and temporomandibular joint (TMJ) with its clinical features and management., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 by Mutaz B. Habal, MD.)

Giant cell tumor of bone (GCTB) is a locally aggressive tumor that shows predilection for the metaphysis/epiphysis of long bones, with an incidence of 4-5% of primary bone tumors. GCTB shows two main populations of cells: mononuclear cells and non-neoplastic multi-nucleated giant cells, with or without fibrous background. On the other hand, giant-cell-poor GCTB are rare with only few reports in the literature. These cases offer a diagnostic challenge, given the absence of giant cells and such cases have consistently been shown to harbor the H3F3A gene mutation by sequencing. The H3.3 G34W mutation-specific monoclonal antibody has shown high specificity in the diagnosis of GCTB. Two cases of giant-cell-poor GCTB are presented in this study, in which giant cells were absent or sparse and the diagnosis of GCTB was confirmed by the expression of H3.3 G34W monoclonal antibody in the mononuclear cells by immunohistochemistry. Whether this represents a histologic variant of GCTB or partial involution of GCTB is not yet fully understood; however, an immune response, infectious/inflammatory reaction, and/or anti-tumor cytokine production have been purported to be factors inciting disease regression in GCTB., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Case: A 31-year-old man with a history of giant cell tumor of bone (GCTB) in the distal radius presents to clinic 9 years after en bloc distal radius resection. He was found to have a new soft tissue mass consistent with GCTB and new pulmonary metastases. Ultimately, he underwent excision of his soft tissue recurrence and partial lobectomy for his lung metastases., Conclusion: This case highlights the importance of having a high level of suspicion for local recurrence or metastasis, even years after wide resection and negative margins., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C185)., (Copyright © 2023 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Fluid-fluid levels (FFLs) is found in 10%-16% of giant cell tumor of bone (GCTB), and the presence of FFLs raises the suspicion of GCTB with secondary aneurysmal bone cyst (ABC), which can lead to increased intraoperative bleeding and, blurring the operative field, be associated with a risk of local recurrence. The first objective of this study is to determine whether secondary ABC is associated with a higher risk of local recurrence after curettage in patients with GCTB of the extremities. The second objective of this study is to investigate the sensitivity, specificity, positive predictive value, and negative predictive value of the presence of FFLs detected on magnetic resonance imaging (MRI) to diagnose secondary ABC associated with GCTB., Methods: Two hundred and eighty patients with GCTB of the extremities who underwent curettage at the authors' institutions between 1980 and 2021 were included in this study., Results: Secondary ABC was found in 36 of 280 patients (12.9%) and local recurrence occurred in 66 of 280 patients (23.6%). Multivariate analysis showed no significant correlation between secondary ABC and local recurrence (hazard ratio [HR]: 1.87 (95% confidence interval [CI]: 1.00-3.53]; p = 0.051). Preoperative MRI revealed FFLs in 13 of 82 patients (15.9%). Sensitivity, specificity, positive predictive value, and negative predictive value of FFLs detected on preoperative MRI to diagnose secondary ABC were 36.8%, 90.5%, 53.8%, and 82.6%, respectively., Conclusion: The results of this study showed that secondary ABC does not increase the risk of local recurrence after curettage in patients with GCTB of the extremities. Although rare, FFLs were present in patients with GCTB and half of those with FFLs detected on preoperative MRI had secondary ABC., (© 2023 Wiley Periodicals LLC.)

Competing Interests: Declaration of interests We declare no competing interests.

Aim: To determine whether computed tomography (CT) texture analysis parameters can be used as quantitative biomarkers to help differentiate giant cell tumour of bones (GCTs), primary aneurysmal bone cysts (PABCs), and aneurysmal bone cysts (ABCs) secondary to giant cell tumours of bone (GABCs)., Materials and Methods: One hundred and seven patients with 63 GCTs, 31 PABCs, and 13 GABCs were analysed retrospectively. All patients underwent preoperative CT. Two radiologists independently evaluated the qualitative features of the CT images and extracted texture parameters. Patient demographics, qualitative features, and texture parameters among GCTs, PABCs, and GABCs were compared statistically. Differences in these parameters between ABCs and GCTs were also assessed. ROC curves were obtained to determine optimal parameter values., Results: The best preoperative CT parameters to differentiate GCTs, PABCs, and GABCs included one qualitative feature (location around the knee) and four texture parameters (95 th percentile, maximum intensity, skewness, and kurtosis). Age and three texture parameters (5 th percentile, inhomogeneity, and kurtosis) enabled statistically significant differentiation between GCTs and ABCs. Combination of the above four parameters generated the largest area under the ROC curve (AUC) for the differentiation of GCTs and ABCs., Conclusion: CT texture analysis parameters can be used as quantitative biomarkers for preoperative differentiation among GCTs, PABCs, and GABCs., (Copyright © 2023 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: Although total en bloc spondylectomy (TES) is strongly recommended for spinal giant cell tumor (GCT), it is extremely difficult to excise a L5 neoplasm intactly through the single-stage posterior approach. Given the risk of neurological and vascular injury, intralesional curettage (IC) is usually recommended for the treatment of L5 GCT. In this study, we presented our experience with the use of an improved TES to treat L5 GCT through the single-stage posterior approach., Methods: This study included 20 patients with L5 GCT who received surgical treatment in our department between September 2010 and April 2021. Of them, seven patients received improved TES without iliac osteotomy, and the other 13 patients received IC (n = 8), sagittal en bloc resection (n = 1), TES with iliac osteotomy (n = 3), and TES with radicotomy (n = 1) as control., Results: The mean operative time was 331.43 ± 92.95 min for improved TES group and 365.77 ± 85.17 min for the control group (p = 0.415), with the mean blood loss of 1142.86 ± 340.87 ml vs. 1969.23 ± 563.30 ml (p = 0.002). Postoperative treatment included bisphosphonates in nine patients and denosumab in 12 patients including one patient who changed from bisphosphonates to denosumab. Three patients who received IC experienced local recurrence, and no relapse was observed in improved TES group., Conclusion: Single-stage posterior TES for L5 GCT was previously considered impossible. In this study, we presented our experience with the use of an improved surgical technique for L5 TES through the single-stage posterior approach, which has proved to be superior to the conventional procedures in terms of blood loss control and complication and recurrence rates., Level of Evidence: IV., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Giant cell tumor of bone (GCTB) is a common primary bone tumor with latent malignant tendency. GCTB is prone to occur around the knee joint, and surgery is the major treatment method. There are relatively few reports on denosumab in the treatment of recurrent GCTB around the knee joint and postoperative function evaluation of patients. This research aimed to explore the appropriate surgical options for the treatment of recurrent GCTB around the knee joint., Patients and Methods: 19 patients with recurrent GCTB around the knee joint, who were admitted to Hospital for 3 months following denosumab treatment from January 2016 to December 2019, were included as the research subjects. The prognosis was compared between patients treated with curettage combined with polymethylmethacrylate (PMMA) and those with extensive-resection replacement of tumor prosthesis (RTP). A deep learning model of Inception-v3 combined with a Faster region-based convolutional neural network (Faster-RCNN) was constructed to classify and identify X-ray images of patients. The Musculoskeletal Tumor Society (MSTS) score, short form-36 (SF-36) score, recurrence, and the rate of complications were also analyzed during the follow-up period., Results: The results showed that the Inception-v3 model trained on the low-rank sparse loss function was obviously the best for X-ray image classification, and the classification and identification effect of the Faster-RCNN model was significantly better than that of the convolutional neural network (CNN), U-Net, and Fast region-based convolutional neural network (Fast-RCNN) models. During the follow-up period, the MSTS score in the PMMA group was significantly higher than that in the RTP group (p<0.05), while there was no significant difference in the SF-36 score, recurrence, and the rate of complications (p>0.05)., Conclusions: The deep learning model could improve the classification and identification of the lesion location in the X-ray images of GCTB patients. Denosumab was an effective adjuvant for recurrent GCTB, and widely extensive-resection RTP could reduce the risk of local recurrence after denosumab treatment for recurrent GCTB.

As a locally aggressive primary benign tumor, giant cell tumor of bone (GCTB) presents a challenge to surgeons, as it often recurs regardless of surgical resection. This report describes a case of GCTB of the distal femur in a man, aged 39 years, treated with intralesional curettage through an arthroscopic approach. A 360° view of the tumor cavity can be achieved with the help of an arthroscope, which can help complete intralesional curettage and minimize possible larger approach-related complications. The result is favorable in terms of functional outcome and recurrence after 1-year follow-up.

BACKGROUND Giant cell tumors of the bone (GCTB) are rare, locally aggressive benign neoplasms that primarily occur in the metaphyses of long bones. In less than 2% of cases, GCTBs arise in the spine, predominantly below the sacrum. We report the clinical manifestations, diagnostic approach, and successful surgical treatment of a patient with a GCTB of the thoracic spine. CASE REPORT A 21-year-old female patient presented to the Emergency Department with back pain and upper motor neuron syndrome. A thorough clinical and imaging examination revealed a tumor and pathological fracture of the T7 vertebra. Histopathological analysis confirmed the diagnosis of a GCTB. The tumor was successfully excised surgically via a posterior thoracic approach, including bilateral decompressive laminectomy, lateral costotransversectomy, and posterior corpectomy, followed by transpedicular instrumentation of the T5-T6 and T8-T9 vertebrae, and anterior arthrodesis with an autologous graft. The patient also received adjuvant radiotherapy. One year later, the patient had no signs of recurrence or physical limitations. CONCLUSIONS GCTBs located in the thoracic spine are uncommon and pose a significant challenge for healthcare professionals due to their non-specific clinical manifestations and the need for a multidisciplinary approach to their management. This case highlights the diagnostic and therapeutic implications of a GCTB of the thoracic spine and describes a successful surgical strategy resulting in complete recovery. The presented case adds to the limited published literature on GCTBs in this unusual location and further elaborates on their presentation and management.

Objectives: This retrospective study describes a pilot experience in CT-guided RadioFrequency Ablation (RFA) treatment of 5 Giant Cell Tumour of the bone (GCT) recurrences after surgery., Methods: After biopsy to confirm the diagnosis of GCT recurrences, all patients were treated with RFA in a single session. A close follow-up was scheduled with contrast-enhanced MRI starting 1 months after treatment., Results: Five lesions were treated in 5 patients. The length of the observation period was between 4 and 100 months. One lesion relapsed 4 months after the RFA treatment, and the patient underwent a second surgical treatment which included the en-block resection and prosthetic implant. No complications were recorded., Conclusions: The management of GCT relapses with RFA could be an interesting and innovative field. However, the results of this limited series need to be confirmed by further investigations of larger patient cohorts., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).)

Background: Currently, little is known about the prognostic value of tumor growth rate (TGR) in spinal giant cell tumors of bone (GCTB)., Objective: To investigate the correlation of TGR with clinicopathological features, immune microenvironment, prognosis, and response to denosumab treatment of spinal GCTB., Methods: A total of 128 patients with spinal GCTB treated at 5 centers from 2011 to 2021 were included. TGR was assessed by 2 independent neuroradiologists using at least 2 preoperative thin-section magnetic resonance imaging scans at a minimum interval of 2 months. Immunohistochemistry was used to assess tumor-infiltrating lymphocyte subtypes for CD3, CD4, CD8, CD20, PD-1, PD-L1, and Foxp3. Then, these parameters were analyzed for their associations with patient outcomes (progression-free survival and overall survival), clinicopathological features, and denosumab treatment responsiveness., Results: High TGR predicted both poor progression-free survival and overall survival (both P < .001). In addition, TGR was associated with postoperative neurological dysfunction ( P < .001), Enneking staging ( P = .016), denosumab treatment responsiveness ( P = .035), and the number of CD3 + ( P < .001), PD-1 + ( P = .009), PD-L1 + ( P < .001), and FoxP3 + tumor-infiltrating lymphocyte ( P = .02). Importantly, TGR outperformed the traditional Enneking, Campanacci, and American Joint Committee on Cancer staging systems in predicting the clinical outcomes of spinal GCTB., Conclusion: These data support the use of TGR as a reliable predictive tool for clinically relevant outcomes and response to denosumab therapy of spinal GCTB, which may be helpful in guiding prognostic risk stratification and therapeutic optimization of patients., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Purpose: Our objectives were (1) to compare the recurrence, metastases, and complication rates of patients with Enneking stage 3 GCTB who underwent extended curettage vs wide resection and (2) examine the factors which might influence surgical options for each patient., Methods: We retrospectively reviewed the records of patients with Enneking stage 3 GCTB from January 2006-December 2015. Extended curettage was performed in patients in whom there was a moderate expansile lesion, minimal/no articular cartilage damage, and less than 50% of cortical deformation compared to its circumference from a CT scan/MRI. The percentages of cortical deformation were collected. Surgical complications, recurrence, and metastatic rates were analyzed., Results: There were 28 extended curettage and 41 wide resections. The mean percentages of cortical deformation compared to circumference were 52.6% (range, 23.9-81.9%) and 91.6% (range, 52.1-100%)(P < 0.01) for the curettage and wide resection groups, respectively. There were three recurrences, 2/28 (7.1%) from the curettage group and 1/41 (2.4%) from the resection group (P = 0.56). There were no cases of pulmonary metastasis. There were two complications in the curettage group and five complications in the resection group., Conclusion: Both extended curettage and wide resection are useful methods to treat Enneking stage 3 GCTB. Extended curettage with proper technique is a viable option showing no difference in local recurrence rate and potentially fewer complications. Preference to do extended curettage in patients in whom when the articular cartilage has minimal or no destruction, a moderate expansile lesion and the cortical deformation is less than 50% of the circumference., (© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Objective: The aims of this work are to present a classification of "complex fracture" and "simple fracture", to compare their features, treatments and prognosis in patients with giant cell tumour with pathologic fractures around the knee, and to determine the best surgical method for patients who have giant cell tumour around the knee with different degrees of fracture., Methods: Data from 130 patients with pathologic fractures from giant cell tumour around the knee who underwent surgical treatment from March 2000 to November 2015 at 6 institutes around China were collected and analysed. A multicentric study design was used to explore the epidemiological features and to compare differences in the surgical procedures and prognosis of the two fracture groups. The mean age at diagnosis was 37.1 years old (range, 13-77 years). The median follow-up was 126.5 months, ranging from 68 to 370 months., Results: The general clinical and imaging features of the groups of patients with simple and complex fractures, namely, sex, age, the lesion site, living or working environment, eccentric growth patterns, Campanacci grading system, and duration of symptoms before treatment, showed varying degrees of differences, but with no statistical significance (p > 0.05). The incidence rate of surrounding soft tissue mass was 35.2% (32/91) in the group with simple fractures, whereas it was 87.2% (34/39) in the group with complex fractures, which showed a significant difference (p < 0.05). Wide resection and reconstruction with joint replacement were performed more often in patients with complex fractures (61.5%, 24/39). Intralesional procedures were performed more often in patients with simple fractures (56.0%, 51/91). The difference showed significant differences (p < 0.05). The local recurrence rate was 17.6% (16/91) in the group with simple fractures, whereas it was 10.3% (4/39) in the complex fracture group, showing a significant difference (p < 0.05). A total of 2.3% of patients (n = 3,3/130) developed a skip lesion. The complication rates were 4.6% (4/87) and 14.7% (5/34), respectively, in the two groups with simple or complex fractures, showing a significant difference (p < 0.05). The mean MSTS and TESS scores with simple fractures were 26.6 (range, 13-30) and 84.1 (range, 29-100), respectively, whereas the mean scores in the group with complex fractures were 25.5 (range, 18-30) and 78.3 (range, 30-100), respectively, also showing a significant difference (p < 0.05)., Conclusion: Our classification of "simple fracture" and "complex fracture" could guide decisions regarding the best surgical method for lesions in patients who have giant cell tumour around the knee with different degrees of fracture., (© 2022. The Author(s).)

Giant cell tumor (GCT) is a benign, locally aggressive neoplasm with little incidence at the carpal bone level. We present a case of pyramidal bone GCT that required open biopsy for diagnosis. As a definitive treatment, en bloc resection of the pyramidal bone and luno-capitate arthrodesis were performed to avoid frequent relapses of these neoplasms and ensure proper functionality of the anatomical segment.

Background: In all giant-cell-rich lesions (GCRL) occurring in bone, a common underlying excessive RANKL expression is held responsible for the osteolytic activity. Apart from giant cell tumour of bone (GCTB), systematic outcome analysis of RANKL inhibition in other GCRL is unavailable. The aim of this study is to assess the efficacy and safety of a 1-year denosumab protocol in giant cell lesions of the jaw (GCLJ)., Methods: A retrospective cohort study was conducted compromising patients treated with a 1-year protocol of monthly subcutaneously administered 120 mg denosumab. Objective tumour response based on histology and imaging was used to calculate objective tumour response rate, progression-free survival (PFS) and time to progression. Type, severity and frequency of adverse events were recorded in a standardised way to assess safety., Results: Twenty patients, predominantly female (90%), were included. Fifty-five per cent of lesions were located in the mandible; most classified as aggressive lesions (90%). Thirty-five per cent (7/20) of cases were either recurrent after prior treatment or progressive, while on other drug treatment. Objective tumour response rate was 100% after 12 months of treatment. Median PFS was 50.4 months (95% CI 38.0-62.8) with a cumulative PFS rate of 22.6% (95% CI 1.8-43.4) at 5 years follow-up. Median time to progression was 38.4 months (95% CI 26.0-50.8). Treatment was well tolerated, and none of the patients had to interrupt therapy for toxicity., Conclusion: High-dose denosumab is effective and safe in achieving a complete response in GCLJ within 12 months. The high long-term relapse rate after treatment cessation is the main obstacle for denosumab to become standard treatment for GCLJ., Competing Interests: Conflict of interest statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Denosumab is a game-changing drug for giant cell tumor of bone (GCTB); however, its clinical biomarker regarding tumor ossification of GCTB has not been elucidated. In this study, we investigated the relationship between Wnt/β-catenin signaling and the ossification of GCTB and evaluated whether endogenous nuclear β-catenin expression predicted denosumab-induced bone formation in GCTB. Genuine patient-derived primary GCTB tumor stromal cells exhibited osteoblastic characteristics. Identified osteoblastic markers and nuclear β-catenin translocation were significantly upregulated via differentiation induction and were inhibited by treating with Wnt signaling inhibitor, GGTI-286, or selective Rac1-LEF inhibitor, NSC23766. Furthermore, we reviewed the endogenous ossification and nuclear β-catenin translocation of 86 GCTB clinical samples and elucidated that intra-tumoral ossification was significantly associated with the nuclear translocation. Three-dimensional quantitative analyses (n = 13) of tumoral CT images have revealed that the nuclear β-catenin translocation of naïve GCTB samples was significantly involved with the denosumab-induced tumor ossification. Our findings suggest a close relationship between the nuclear β-catenin translocation and the osteoblastic differentiation of GCTB. Investigations of the nuclear β-catenin in naïve GCTB samples may provide a promising biomarker for predicting the ossification of GCTB following denosumab treatment., (© 2022. The Author(s).)

Background: Giant cell tumors (GCTs) and giant cell granulomas (GCGs) are giant cell-rich lesions that occur extremely rarely in the temporal bone and have similar clinical presentations., Objectives: We aimed to analyze the clinical features and introduce our staging system and surgical treatment., Methods: Forty-six patients pathologically diagnosed with a giant cell lesion involving the temporal bone between October 2001 and October 2020 were reviewed retrospectively. The clinical characteristics, surgical approaches, and risk factors for recurrence were analyzed., Results: GCTs and GCGs presented as masses centered on the temporomandibular joint with similar imaging features, including a thin, calcified shell and central scattered calcifications on a computed tomography scan. Differences were detected on magnetic resonance imaging in 29.6% (4/14) of GCG and 50% (16/32) of GCT cases; the remaining cases were not distinguishable. Based on our staging system and surgical strategy, 31.8% (7/22) of GCT and 10% (1/10) of GCG cases experienced recurrence, which compares to recurrence rates of 60% in GCT cases and 20% in GCG cases in previous studies., Conclusions: Specific clinical and preoperative imaging features help to make a diagnosis of temporal giant cell-rich lesions. Our staging system and surgical strategy could help surgeons tailor the surgical strategy.

Study Deign: This was a retrospective study about sacral giant cell tumor of bone (GCTB)., Objective: This study aimed to investigate whether ultra-short course of neo-adjuvant denosumab treatment for sacral GCTB could (1) induce radiological and histological response? (2) Facilitate nerve-sparing surgery? (3) Achieve satisfactory oncological and functional outcomes?, Summary of Background Data: Previous reports on long course of neo-adjuvant denosumab treatment for GCTB showed significant tumor response and a relatively high recurrent rate after curettage., Methods: Sixty-six patients with sacral GCTB treated with neoadjuvant denosumab and nerve-sparing surgery were categorized into ultra-short course group (≤3 doses and operation within D21 since 1st dose, 41 patients) or conventional group (>3 doses or operation after D21 since 1st dose, 25 patients). The radiological and histological response, operative data, oncological and functional outcomes were compared., Results: The ultra-short course group demonstrated fewer doses of neo-adjuvant denosumab (mean: 2.1 vs. 4.8, P  < 0.001) and shorter time to surgery (12.2 days vs. 72.3 days, P < 0.001). Similar patterns of radiological and histological response were observed in the two groups with less fibrosis and ossification in the ultra-short course group. The operative duration (199.9 min vs. 187.8 min, P = 0.364) and estimated blood loss (1552.4 mL vs. 1474.0 mL, P = 0.740) were comparable. Most (94.8%) of the patients received adjuvant denosumab. After a mean follow-up of 29.4 months, three cases (8.8%) and five cases (20.8%) showed local recurrence in each group (P = 0.255). The estimated recurrence-free survival (56.2 vs. 51.2 months, P = 0.210) and the functional status [Motor-Urination-Defecation scores: 25.9 vs. 25.7, P = 0.762] did not differ between the two groups., Conclusion: Ultra-short course of neo-adjuvant denosumab for sacral GCTB could elicit radiological and histological responses as conventional course did. The less degree of fibrosis and ossification might facilitate nerve-sparing surgery and help to achieve satisfactory local control and functional status.Level of Evidence: 4., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Giant cell tu mour accounts for up to 5% of all bone tumours and malignant giant cell tumour arises in < 10% of cases, representing sarcomatous transformation. Primary malignant giant cell tumour of bone occurs when sarcomatous tissue is observed within conventional giant cell tumour histologically on initial presentation. Secondary malignant giant cell tumour of bone occurs in a region of previously treated giant cell tumour, with most cases arising due to prior radiotherapy. Malignancy in giant cell tumour of bone does not have any unique clinical or imaging features compared to conventional aggressive disease. Historically, malignant giant cell tumour of bone has a poor prognosis which is worse in cases of secondary malignancy. This article aims to present the clinical, pathological and imaging features of MGCTB based on a review of the literature and illustrated by examples from our experience., (© 2021. ISS.)

Abstract: A 99mTc-sestamibi parathyroid scintigraphy was performed in a 27-year-old woman to evaluate possible hyperparathyroidism. The images did not identify any parathyroid abnormality. However, an intense activity was noted in the proximal left upper extremity, which was confirmed as giant cell tumor of the proximal left humerus by pathological examination., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Giant cell tumor of bone (GCTB) is an intermediate but locally aggressive neoplasm. Current treatment of high-risk GCTB involves administration of denosumab, which inhibits bone destruction and promotes osteosclerosis. However, denosumab monotherapy is not a curative treatment for GCTB and surgical treatment remains required. Denosumab treatment complicates surgery, and the recurrence rate of GCTB is high (20%-30%)., Purpose: To examine the utility of intraoperative magnetic resonance imaging (iMRI) for detection and reduction of residual tumor after denosumab treatment and to investigate the utility of iMRI, which is not yet widely used., Material and Methods: We enrolled five patients who received denosumab for a median period of eight months (range 6-12 months). Surgery was performed when the degree of osteosclerosis around the articular surface was deemed appropriate. We performed iMRI using a modified operation table to identify residual tumor after initial curettage and evaluated the rate of detection of residual tumor by iMRI, intraoperative and postoperative complications, exposure time of iMRI, and operation time., Results: Suspected residual tumor tissue was identified in all five cases and was confirmed by histopathology after additional curettage. The rate of detection of residual tumor by iMRI was 100%. Residual tumor was located in sites which were difficult to remove due to osteosclerosis. The iMRI was performed safely and without trouble. During the median follow-up period of 10 months (range 6-24 months), no adverse events or recurrences occurred., Conclusion: Intraoperative MRI could contribute to the reduction of residual tumor tissue and it may prevent recurrence of GCTB after denosumab therapy.

Background: Extended curettage has increasingly become the preferred treatment for giant cell tumour of bone (GCTB), but the high recurrence rate after curettage poses a major challenge for orthopaedic surgeons. Computed tomography (CT) is valuable in the evaluation of GCTB. Our aim was to identify specific features of GCTB around the knee in pre-operative CT images that might have prognostic value for local recurrence., Methods: We retrospectively analyzed data from 124 patients with primary GCTB around the knee who underwent extended curettage from 2010 through 2019. We collected demographic, clinical, and therapeutic data along with several CT-derived tumour characteristics. CT-derived tumor characteristics included tumour size, the distance between the tumour edge and articular surface (DTA), and destruction of posterior cortical bone (DPC). Akaike information criterion (AIC) was used to select which variables to enter into multivariate logistic regression models and to determine significant factors affecting recurrence., Results: The total recurrence rate was 21.0% (26/124), and the average follow-up time was 69.5 ± 31.2 months (24-127 months). Age, DTA (< 2 mm), and DPC were significantly related to recurrence, as determined by multivariate logistic regression. The C-index of the final model was 0.79 (95% CI: 0.71 to 0.88), representing a good model for predicting recurrence., Conclusion: Identifying certain features of GCTB around the knee on CT has prognostic value for patients treated with extended curettage. A three-factor model predicts tumour recurrence well after extended curettage., (© 2021. The Author(s).)

Purpose: Giant cell tumour (GCT) of the bone is a benign but locally aggressive tumour, commonly occurs at the metaphyseal-epiphyseal junction of the distal femur, proximal tibia, and distal radius. For Campanacci grade II and III lesions of the distal radius and in cases of recurrence, we usually carry out wide resection and reconstruction. There are numerous publications on the treatment of GCT of the distal radius. Still, reports on the functional outcome using non-vascularized fibular graft arthroplasty without fusion remain limited., Method: We reviewed patients who underwent wide resection and non-vascularized fibular graft arthroplasty from 2007 to May 2014. The assessment was done with Musculoskeletal Tumour Society Score (MSTS), Toronto Extremities Scoring System (TESS) and Disability of the Arm, Shoulder and Hand (DASH) scores. We also reviewed the radiographic results., Results: Fifteen patients were recruited, of whom 10 cases used ipsilateral fibular graft and five used contralateral non-vascularized fibular graft. The average duration of follow up was 6 years (3.25-9.92 years). The average grip strength was 48.1% compared to the non-operated hand. The average MSTS score was 78.4 %, TESS score was 84%, and DASH score was 25.2. The average time to radiological union was 12.5 weeks. 64% (29-78%) of the range of movement is preserved compared to the normal side. The complication rate was 20%., Conclusion: Fibula autograft arthroplasty is a feasible method of reconstruction after distal radius resection with good functional outcomes.

Background: Femoral bone deficiency is a challenging problem in revision proximal femoral replacement. The purpose of this study is to evaluate the clinical and radiological outcomes of revision proximal femoral replacement as a salvage treatment for severe bone loss after oncologic proximal replacement surgery in patient with benign giant cell tumor of bone., Methods: 16 patients (6 men and 10 women) were included in this retrospective study, with a mean age of 46.6 year at the time of revision surgery. All patients underwent revision proximal femoral replacement with the use of modular prosthesis and cortical strut allografts. The modified Harris Hip Score, Short Form 36, and musculoskeletal Tumor Society Score were used for patient evaluation. Regular follow-up was performed to evaluate the recurrence and metastases rate, limb function, and long-term complications of patients., Results: The average follow-up was 46.3 months (range, 26-75 months), during which there was no local recurrence and metastases of patient. At the latest follow-up, the mean modified Harris Hip Score was 70.6 points, which was significantly improved compared with that of preoperative ( p < 0.05). The final follow-up results of Short Form 36, Musculoskeletal Tumor Society Score, and limb-length discrepancy were also significantly improved compared to that of preoperative ( p < 0.05). At the latest follow-up, the implanted femoral stems were all stable and all cortical strut allografts were also incorporated to their own bone., Conclusion: Using modular prosthesis and cortical strut allografts in revision, proximal femur replacement is an acceptable procedure for relatively young patient with severe proximal femoral bone loss after oncologic surgery with benign giant cell tumor of bone. More attentions should be paid to reduce the risk of complications in these complex reconstructions.

The hand is an extremely rare site for giant cell tumor (GCT). There are only a few reported cases of GCT including the hand, and even fewer reporting involvement of phalanges. GCTs in small bones are typically more aggressive and have higher local recurrence and rate of metastasis in younger patients compared to long bone involvement, so the treatment is more clinically challenging in the hand. In this study, we present the management of giant cell tumors of the proximal phalanxin two patients treated with two different method; ray resection and arthrodesis using an iliac crest graft. Key words: giant cell tumor, phalanx, hand, recurrence.

Giant cell tumour of bone (GCTB) typically occurs in young adults from 20-40 years old. Although the majority of lesions are located in the epi-metaphyses of the long bones, approximately one third of tumours are located in the axial skeleton, of which only 4% in the sacrum. Sacral tumours tend to be large at the time of presentation, and they present with aggressive features such as marked cortical destruction and an associated soft tissue component. The 2020 World Health Organisation classification of Soft Tissue and Bone Tumours describes GCTB as a neoplasm which is locally aggressive and rarely metastasizing. The tumour contains three different cell types: neoplastic mononuclear stromal cells, macrophages and osteoclast-like giant cells. Two tumour subtypes were defined: conventional GCTB and malignant GCTB. Only 1-4% of GCTB is malignant. In this review article, we will discuss imaging findings at the time of diagnosis to guide the musculoskeletal radiologist in reporting these tumours. In addition, imaging for response evaluation after various treatment options will be addressed, such as surgery, radiotherapy, embolization and denosumab. Specific findings will be presented per imaging modality and illustrated by cases from our tertiary sarcoma referral center. Common postoperative and post-radiotherapy findings in GCTB of the sacrum on MRI will be discussed., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Giant cell tumor of bone (GCTB) is a primary bone tumor which comprises giant cells and two types of stromal cells. Recent studies have suggested therapeutic risks of denosumab. No previous studies have reported changes in serum TRACP-5b and SUVmax of 18 F-FDG-PET/CT in recurred GCTB after denosumab treatment. Therefore, we assessed the relationship between clinical and pathological features of GCTB which recurred after denosumab treatment., Methods: We retrospectively reviewed the medical records of 26 patients with GCTB who underwent curettage between 2010 and 2018. Fourteen patients treated with denosumab were defined as the denosumab group. We evaluated TRACP-5b and SUVmax values in the denosumab group. H&E staining and immunohistochemistry for H3.3 G34W were performed for pathological assessment. Twelve patients treated without denosumab were defined as the non-denosumab group and compared with denosumab group., Results: The local recurrence rate in the denosumab group was 57.4%. The mean TRACP-5b and SUVmax values were significantly decreased after denosumab therapy (P < 0.001, 1077 ± 161 to 74 ± 9 mU/dL and 8.88 ± 0.40 to 3.79 ± 0.56, respectively). Both parameters significantly increased with local recurrence. H&E staining after denosumab treatment revealed the disappearance of giant cells and histological changes in stromal cells. Specimens of local recurrence subjected to H&E staining and immunohistochemistry for H3.3 G34W demonstrated almost identical features to those in the first biopsy., Conclusion: Although denosumab can prevent GCTB from osteolysis, local recurrence cannot be reduced by denosumab treatment. The clinical and pathological results were almost the same as those before denosumab treatment, suggesting that the changes of GCTB by denosumab are reversible., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)