Search

Desmoid fibromatosis is a rare subtype of soft tissue neoplasms known for its locally aggressive behaviour and fibrotic consistency. While these tumours can arise in various anatomical sites, their occurrence within the colon is exceptionally rare and poses diagnostic and therapeutic challenges. We present a case of a female patient in her 30s with no significant medical history who presented with vague gastrointestinal and urinary symptoms. Imaging studies revealed a sizeable abdominal mass, initially raising uncertainty regarding its origin. Subsequent exploratory laparotomy revealed a desmoid fibromatosis involving the muscularis propria of the caecum, prompting a right hemicolectomy. Histopathological analysis confirmed the diagnosis, and the patient underwent a successful resection with negative margins. This case underscores the importance of individualised treatment plans and long-term surveillance in managing colonic desmoid tumours for optimal outcomes and disease-free survival., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Objective: This study aimed to compare the expression of lymphoid enhancer factor 1 (LEF1) and β-catenin in basal cell adenoma (BA), desmoid-type fibromatosis (DF), and pancreatic solid pseudopapillary neoplasm (SPN) to evaluate their diagnostic utility in tumors associated with the WNT/β-catenin signaling pathway harboring the mutation of CTNNB1 gene 3 exon., Methods: Eighty tumor patients, including 26 BAs, 30 DFs, and 24 SPNs, were analyzed. Immunohistochemical staining was identified positive (nuclear staining of LEF1 and β-catenin in > 50% of tumor cells). The diagnostic rate of LEF1 alone, β-catenin alone, and their combination were compared for each tumor type and all patients., Results: Compared to β-catenin, when LEF1 alone was used for diagnosis, the diagnostic rate increased by 46.16% for BA, 16.67% for SPN, and 11.25% for all patients, but decreased by 23.34% for DF. The combined use of β-catenin and LEF1 significantly increased the diagnostic ratio in BA (46.16%), SPN (16.67%), and all patients (21.25%), but only marginally in DF (3.33%). In terms of all WNT pathway tumors with CTNNB1 gene mutation encompassed by our study, statistical analysis revealed no significant difference between LEF1 alone and β-catenin alone. However, their combined application was highly significant (P = 0.001) ., Conclusion: While β-catenin is commonly used as a marker for WNT pathway tumors, its variable expression and localization can be challenging for diagnosis. Our study emphasizes the importance of LEF1 as a complementary marker to β-catenin in diagnosing BA, DF, SPN, and other WNT pathway tumors activated by exon 3 CTNNB1 gene mutation. The combined use of LEF1 and β-catenin enhances diagnostic accuracy and may help the identification of these tumor types., Competing Interests: Declarations. Ethics approval and consent to participate: This study was conducted with approval from the Ethics Committee of Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine (Approval No. XHEC-D-2024-075). This study was conducted in accordance with the declaration of Helsinki. Written informed consent was obtained from all participants. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

We present the case of a man in his 60s with hypertension, who had a 3-year history of an irreducible mass in the left inguinal area. The patient presented at the emergency room with left lower quadrant pain and scrotal pain. The clinical examination was not suggestive of an acute abdomen. A CT scan was done showing an anterior abdominal wall defect at the left inguinal region. The patient underwent exploratory laparotomy, ileal resection and anastomosis, mesh hernioplasty left for the mesenteric fibromatosis mass mimicking as an irreducible inguinal hernia. Histopathology and immunohistochemistry showed desmoid-type fibromatosis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Background: Radiotherapy is considered an alternative treatment for unresectable or pharmacologically resistant desmoid-type fibromatosis. While it results in relatively good local control, the risk of secondary malignancy remains a concern., Case: We present a case of secondary osteosarcoma after carbon-ion radiation therapy (CIRT). A 31-year-old male patient presented with left thigh pain. The tumor was located between the left gluteus maximus and gluteus medius and extended to the vastus lateralis and biceps femoris. It was diagnosed as desmoid-type fibromatosis after needle biopsy. The patient was treated with several medications, including a cyclooxygenase 2 inhibitor and tamoxifen; however, his left thigh pain did not improve. He was treated with CIRT 1 year after diagnosis (67.2 Gy [relative biological effectiveness] 16fr/4wks). He developed osteosarcoma of the left femur 8 years later. He underwent chemotherapy and tumor excision with disarticulation of the left hip. Pulmonary metastasis was detected 6 and 17 months after the definitive surgery and excised using metastasectomy. However, he died due to the recurrence of multiple pulmonary metastases 29 months after the definitive surgery., Conclusions: In this case, we believe that the low radiation dose to the femur may have caused secondary malignancy., (© 2024 The Author(s). Cancer Reports published by Wiley Periodicals LLC.)

The patient was a 47-year-old woman. She had been aware of abdominal distension for several months and visited our hospital. Contrast CT revealed a 30 cm tumor with uneven contrast effect. MRI showed uniform low signal intensity on T1 weighted images and a mixture of low and high signal intensity on T2 weighted images. She was diagnosed with a giant ovarian tumor and underwent surgery at the gynecology department. Laparotomy revealed that the tumor originated in the small intestine mesentery rather than the ovary, and she was referred to our department during surgery. The tumor had involved the ileocolic artery and vein, and was removed by right hemicolectomy. The specimen was 32×32×27 cm and weighed approximately 8 kg. Histopathological examination showed proliferation of spindle cells. Immunohistochemistry showed negative staining for c-kit and positive staining for β-catenin. The tumor was diagnosed as an intra-abdominal desmoid tumor. Intra-abdominal desmoid is a rare disease, and diagnosis and surgical procedure are often difficult. We report a case of resection of a giant mesenteric desmoid tumor with a review of the literature.

Rationale: Desmoid tumor (DT) is a rare soft tissue tumor that can occur anywhere in the body. Abdominal wall DT presents unique clinical challenges due to its distinctive manifestations, treatment modalities, and the lack of biomarkers for diagnosis and recurrence prediction, making clinical decisions exceedingly complex., Patient Concerns: A 32-year-old female who underwent radical resection combined with patch reinforcement for rectus abdominis DT, successfully alleviating abdominal discomfort, with no recurrence during the 6-month follow-up after surgery., Diagnoses: Based on the imaging studies and medical history, the patient underwent radical surgical resection. Histopathology reveals that the tumor cells predominantly composed of proliferative fibroblasts with local collagen deposition. The lesional cells show positive staining for β-catenin, indicating a diagnosis of DT., Interventions: The patient underwent radical surgical resection with patch reinforcement to repair the abdominal wall defect. Pathology confirmed negative margins, achieving an R0 resection, and genetic testing identified a T41A mutation in CTNNB1. Consequently, no additional adjuvant therapy was administered postoperatively., Outcomes: The patient was discharged with the incision healing well after 3 days postoperation. Upon reexamination 6 months later, no recurrence or adverse complications were observed., Lessons: Abdominal wall DT treatment requires personalized plans from multidisciplinary team discussions. Genetic testing plays a crucial role in identifying novel biomarkers for abdominal wall DT. We have once again demonstrated the significant clinical significance of CTNNB1 mutations in the diagnosis and progression of abdominal wall DT. Additionally, genes such as CCND1, CYP3A4, SLIT1, RRM1, STIM1, ESR2, UGT1A1, among others, may also be closely associated with the progression of abdominal wall DT. Future research should delve deeper into and systematically evaluate the precise impact of these genetic mutations on treatment selection and prognosis for abdominal wall DT, in order to better guide patient management and treatment decisions., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Rationale: Aggressive fibromatosis (AF) is a fibroblastic/myofibroblastic tumor known for its locally aggressive properties. Intra-abdominal AF primarily occurs in the small intestine mesentery, ileocolic mesocolon, omentum, retroperitoneum, and pelvis, and rarely originates from the intestinal wall. Here, we report a rare case of small bowel obstruction caused by duodenum-derived AF with β-catenin (CTNNB1) T41A mutation., Patient Concerns: A 35-year-old male had a 4-month history of abdominal pain, nausea, and vomiting, which gradually worsened over time., Diagnoses: Based on the results of CT examination, histopathology and Sanger sequencing, the patient was diagnosed with small bowel obstruction caused by duodenum-derived AF., Interventions: Due to the extensive adhesion between the tumor and surrounding tissue, it is extremely challenging to completely remove the tumor through surgical resection with negative margins in this case. In order not to damage the function of surrounding vital organs, gastrojejunostomy was performed to relieve the symptoms of small bowel obstruction., Outcomes: The patient experienced a successful recovery. It is important to note that this patient is still at risk of local recurrence and requires regular follow-up., Lessons: The best treatment should be taken based on the individual patient to relieve symptoms and improve quality of life. Moreover, histopathology plays a crucial role in diagnosing and differentiating duodenum-derived AF. The detection of mutations in exon 3 of the CTNNB1 has become strong evidence for diagnosing duodenum-derived AF., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Abstract: Extra-abdominal desmoid fibromatosis arising from the oesophagus and the contemporaneous traction diverticula due to an oesophageal tumour is extremely rare. We present this complex situation in a 2-year-old girl which posed a surgical challenge requiring simultaneous management of multiple pathologies. Surgery addressed both the entities and the presence of the diverticulum facilitated achieving negative surgical margins., (Copyright © 2024 Copyright: © 2024 African Journal of Paediatric Surgery.)

Purpose: Desmoid fibromatosis in head and neck is infrequent and poses a significant challenge to the clinicians due to its non-specific characteristics., Methods: This case report focuses on a 69-year-old male who presented to a tertiary healthcare center in Karnataka, India with a swelling in the oral cavity., Results: Despite initial suspicions of malignancy based on clinical examination and findings on computed tomography imaging, subsequent histopathology and immunohistochemistry revealed an unexpected finding., Conclusion: The case highlights the importance of clinical suspicion and histopathological evaluation as well as the need for greater awareness to facilitate early diagnosis and appropriate management of desmoid fibromatosis. We also present a literature review of varied presentations of desmoid tumors afflicting various subsites of the head and neck., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Diagnosis of desmoid-type fibromatosis (DF) may be challenging on biopsy due to morphologic overlap with reactive fibrosis (scar) and other uniform spindle cell neoplasms. Evaluation of nuclear β-catenin, a surrogate of Wnt pathway activation, is often difficult in DF due to weak nuclear expression and high background membranous/cytoplasmic staining. Lymphoid enhancer-factor 1 (LEF1) is a recently characterized effector partner of β-catenin which activates the transcription of target genes. We investigated the performance of LEF1 and β-catenin immunohistochemistry in a retrospective series of 156 soft tissue tumors, including 35 DF, 3 superficial fibromatosis, and 121 histologic mimics (19 soft tissue perineurioma, 8 colorectal perineurioma, 4 intraneural perineurioma, 26 scars, 23 nodular fasciitis, 6 low-grade fibromyxoid sarcomas, 6 angioleiomyomas, 5 neurofibromas, 5 dermatofibrosarcoma protuberans, 3 low-grade myofibroblastic sarcomas, 3 synovial sarcomas, 3 inflammatory myofibroblastic tumors, 2 schwannomas, and 1 each of Gardner-associated fibroma, radiation-associated spindle cell sarcoma, sclerotic fibroma, dermatofibroma, and glomus tumor). LEF1 expression was not only seen in 33/35 (94%) of DF but also observed in 19/23 (82%) nodular fasciitis, 7/19 (37%) soft tissue perineurioma, 2/3 (66%) synovial sarcoma, and 6/26 (23%) scar, as well as in 1 radiation-associated spindle cell sarcoma. The sensitivity and specificity of LEF1 IHC for diagnosis of DF were 94% and 70%, respectively. By comparison, β-catenin offered similar sensitivity, 94%, but 88% specificity. Positivity for LEF1 and β-catenin in combination showed sensitivity of 89%, lower than the sensitivity of β-catenin alone (94%); however, the combination of both LEF1 and β-catenin improved specificity (96%) compared to the specificity of β-catenin alone (88%). Although LEF1 has imperfect specificity in isolation, this stain has diagnostic utility when used in combination with β-catenin., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Desmoid-type fibromatosis is a relatively rare disease, often associated with familial adenomatous polyposis and a history of abdominal surgery. A 43-year-old male patient presented with abdominal pain and contrast-enhanced CT showed a mass in the lower abdomen. The mass was a 4×4×3 cm white, dense tumor with a wreath-like arrangement of eosinophilic spindle-shaped cells. Immunostaining showed KIT(-), CD34(-), desmin(-), β-catenin(+), SMA(few+), and the diagnosis was desmoid-type fibrosis. Six months after surgery, there was no apparent recurrence.

Desmoid tumors are soft tissue neoplasms arising from fascial and muscle-aponeurotic structure. These tumors are locally aggressive and have a high recurrence rate, even after complete resection. We present the case of a female with a giant intrathoracic desmoid tumor. She underwent complete surgical resection with no disease recurrence. Desmoid tumors' natural history is not well defined and is often enigmatic, making these tumors difficult to manage. Currently, for intrathoracic desmoid tumors, medical treatment is the recommended approach, nevertheless, surgery can be considered in selected patients.

Opinion Statement: Desmoid tumors are rare tumors with a tendency to infiltrate locally. The lack of a standard treatment approach makes choosing the most appropriate treatment for patients challenging. Most experts recommend watchful observation for asymptomatic patients as spontaneous regression of tumor is observed in up to 20% of patients. Upfront resection of the desmoid tumor has fallen out of favor due to high morbidity and high relapse rates associated with the tumor. Systemic therapy has evolved over several decades. Where chemotherapy, hormonal therapy, and non-steroidal anti-inflammatory drugs were used over the last several decades, tyrosine kinase inhibitors came to the forefront within the last decade. Most recently, gamma-secretase inhibitors have shown significant clinical benefit in patients with desmoid tumors, bringing forth an entirely new mechanistic approach. Several Wnt pathway inhibitors are also under development. Invasive approaches like cryoablation have also shown clinical benefit in patients with extra-abdominal desmoid tumors in recent years. The recent approval of nirogacestat has ushered in a new era of treatment for patients diagnosed with desmoid tumors. Several new molecules are expected to be approved over the coming years., (© 2024. The Author(s).)

Presented are three casuistics of seemingly identical breast lesions which even by adopting advanced laboratory techniques may represent diagnostic challenge. Microscopic features of some bland spindle cell lesions of different histogenesis (epithelial or mesenchymal) are misleading and a potential source of unaware errors, which might affect optimal therapeutic strategy. In the setting of three diverse entities (low-grade spindle cell metaplastic carcinoma, desmoid fibromatosis and phyllodes tumor) is documented both demanding diagnostic algorithm and revealing molecular landscape on one side as well as evolving predictive/prognostic parameters on the other one. Close interdisciplinary cooperation is inevitable for accurate interpretation/understanding of revealed diagnostic facts which is required for adjustment of competent rational and individualized therapy.

Desmoid fibromatosis is a myofibroblastic neoplasm of intermediate biologic potential, which has a strong predilection for local recurrence but does not metastasize. Arranged in long, sweeping fascicles with infiltrative borders, desmoid fibromatosis typically consists of uniform, bland myofibroblastic spindle cells that harbor mutation of CTNNB1 (or less often APC ) . In this report, we present a remarkable case of desmoid fibromatosis associated with striking nuclear pleomorphism. We hypothesize that this striking pleomorphism is due to a germline TP53 mutation, a finding first suspected due to strong and diffuse p53 staining by immunohistochemistry and subsequently confirmed by molecular testing. The combination of the pleomorphism and TP53 mutation in desmoid fibromatosis represents a novel finding unreported in the literature., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: The GODDESS © tool was developed to assess Desmoid Tumor/Aggressive Fibromatosis (DT/AF) symptom severity and impact on patients' lives. This study evaluated GODDESS © 's cross-sectional and longitudinal measurement properties., Methods: The Phase 3, randomized placebo-controlled, DeFi study (NCT03785964) of nirogacestat in DT/AF was used to assess GODDESS © 's reliability, construct validity, responsiveness, and estimate of meaningful change thresholds (MCTs). Other patient-reported outcome (PRO) measures included Patient Global Impression of Severity (PGIS) in DT/AF symptoms, EORTC QLQ-C30, Brief Pain Inventory Short Form, and PROMIS Physical Function short-form 10a v2.0 plus 3 items., Results: DeFi participants (N = 142) had a median age of 34 years (range: 18-76) and were mostly female (64.8%), with extra-abdominal (76.8%) or intra-abdominal tumors (23.2%). The GODDESS © symptom/impact scales showed internal consistency at baseline, cycles 4 and 7 (Cronbach's α > 0.70) and test-retest reliability (intra-class correlation coefficient > 0.85). GODDESS © scales correlated moderately to highly with PRO measures capturing similar content and differentiated among PGIS and Eastern Cooperative Oncology Group groups. GODDESS © scales detected improvement over time. For the total symptom score, a 1.30-point decrease was estimated as the within-person MCT and a 1.00-point decrease as the between-group MCT. For the physical functioning impact score, estimated within- and between-group MCTs were 0.60-point and 0.50-point decreases, respectively. Few participants exhibited symptom worsening., Conclusion: GODDESS © was found to be reliable, valid, responsive, and interpretable as a clinical trial endpoint in the pooled sample of DT/AF patients. Estimated MCTs can be used to define responders and assess group-level differences in future, unblinded, efficacy analyses., Trial Registration Number and Registration Date: NCT03785964; December 24, 2018., (© 2023. The Author(s).)

Desmoid tumors (DT) are rare, locally aggressive, fibroblastic soft-tissue tumors that are characterized by infiltrative growth and can affect organs and adjacent structures, resulting in substantial clinical burden impacting patients' health-related quality of life. Searches of PubMed, Embase, Cochrane, and key conferences were conducted in November 2021 and updated periodically through March 2023 to identify articles describing the burden of DT. Of 651 publications identified, 96 relevant ones were retained. Diagnosis of DT is challenging because of its morphologic heterogeneity and variable clinical presentation. Patients visit multiple healthcare providers, often facing delays in correct diagnosis. The low incidence of DT (estimated 3-5 cases per million person-years) limits disease awareness. Patients with DT experience a high symptom burden: up to 63% of patients experience chronic pain, which leads to sleep disturbance (73% of cases), irritability (46% of cases), and anxiety/depression (15% of cases). Frequently mentioned symptoms are pain, limited function and mobility, fatigue, muscle weakness, and swelling around the tumor. Overall, quality of life in patients with DT is lower than in healthy controls. There is no treatment approved by the US Food and Drug Administration for DT; however, treatment guidelines reference available options, such as active surveillance, surgery, systemic therapy, and locoregional therapy. Choice of active treatment may depend on tumor location, symptoms, and risk of morbidity. The substantial burden of illness of DT is related to difficulties in timely and accurate diagnosis, high symptom burden (pain and functional limitations), and decreased quality of life. There is a high unmet need for treatments that specifically target DT and improve quality of life., (© 2023. The Author(s).)

Sporadic intra-abdominal desmoid tumors are rare and known to potentially occur after trauma including previous surgery, although knowledge of the underlying pathogenetic mechanism is still limited. We reviewed the recent literature on sporadic intraabdominal desmoids and inflammation as we investigated the mutational and epigenetic makeup of a case of multiple synchronous mesenterial desmoids occurring after necrotizing pancreatitis. A 62-year-old man had four mesenteric masses up to 4.8 cm diameter detected on CT eighteen months after laparotomy for peripancreatic collections from necrotizing pancreatitis. All tumors were excised and diagnosed as mesenteric desmoids. DNA from peripheral blood was tested for a multigene panel. The tumour DNA was screened for three most frequent β-catenin gene mutations T41A, S45F and S45P. Expression levels of miR-21-3p and miR-197-3-p were compared between the desmoid tumors and other wild-type sporadic desmoids. The T41A CTNNB1 mutation was present in all four desmoid tumors. miR-21-3p and miR-197-3p were respectively upregulated and down-regulated in the mutated sporadic mesenteric desmoids, with respect to wild-type lesions. The patient is free from recurrence 34 months post-surgery. The literature review did not show similar studies. To our knowledge, this is the first study to interrogate genetic and epigenetic signature of multiple intraabdominal desmoids to investigate potential association with abdominal inflammation following surgery for necrotizing pancreatitis. We found mutational and epigenetic features that hint at potential activation of inflammation pathways within the desmoid tumor., (© 2022. The Author(s).)

Nine cases of mesenteric desmoid-type fibromatosis were diagnosed and treated in Taizhou Hospital, Wenzhou Medical University between January 2010 and May 2022, including 2 females and 7 males, aged 16 to 59 years. The lesions were in the mesentery of small intestine with 7 cases, ileocecal junction with 1 cases and transverse colon with 1 case. The tumors had an unclear boundary and no envelope, the section was solid, gray and tough. The mean maximum diameter was (10.7±8.5) cm (range 3.5-33.0 cm). Microscopically, fusiform fibroblasts and myofibroblasts were parallel, bunched or staggered, buried in a large amount of extracellular collagen. The cell morphology was relatively consistent, without obvious atypia, and mitosis was rare. Immunohistochemistry showed that the tumor cells were positive for vimentin (9/9), β-catenin (9/9), while smooth muscle actin (5/9) stains were focally positive. Ki-67 proliferation index was 1%-10%. Cytokeratin Pan, S-100, STAT6, CD117, DOG1, CD34, desmin and anaplastic lymphoma kinase stains were negative. Genetic analysis showed that there were 7 cases of c.121G>A(p.Thr41Ala) mutation of CTNNB1 gene, 1 case of c.121G>A(p.Thr41Ala) and 1 case of c.134C>T(p.Ser45Phe) double mutation, and 1 case of wild type. Tumors were surgically resected in all 9 cases. Eight cases had no recurrence or metastasis, 1 case had recurrence 6 months later, and no recurrence or metastasis after additional surgical resection.

Aggressive fibromatosis, histologically classified as benign due to the absence of metastasis, is characterised by locally invasive and destructive growth with high recurrence rates after resection. For this reason, prognostic recurrence factors, in particular the extent of resection, are much debated, and treatment decisions seem challenging for interdisciplinary tumour conferences. Between the years 2000 and 2020, 110 patients with aggressive fibromatosis of the extremities or trunk received surgical treatment at BG University Hospital Bergmannsheil (Bochum, Germany). Univariate analyses were performed to detect any potential prognosis factors. The median follow-up time was 5.9 years. A total of 57 (51.8%) of these patients developed recurrence during this period. The 5-year recurrence-free survival was 52.9% (95% CI: 42.4-62.3) in the entire cohort. In R0-resected patients, the 5-year recurrence-free survival (RFS) was significantly better (p<0.001) at 69.2% compared with patients with R1 or R2-resected tumours (32.6%). Beyond that, no other significant influencing factors were identified. The results of this study indicate that R0 resection or R0 resectability were associated with a significantly better local control. The therapeutic recommendation for resection should be made individually by an interdisciplinary tumour board in due consideration of tumour progression, possible therapeutic alternatives, and foreseeable functional impairment., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Introduction: Desmoid fibromatosis is a multifactorial disorder classified as a category of intermediate, locally aggressive behaviour, which might be associated with CTNNB1 or APC mutations, trauma, surgery, or pregnancy., Case Reports: We present two cases of postoperative intra-abdominal desmoid fibromatosis. The first case occurred 14 months after the resection of a retroperitoneal gastrointestinal stromal tumour. The second case was located in the mesentery, as evidenced on an 18-month followup after a laparoscopy-assisted anterior resection for adenocarcinoma at the rectosigmoid junction. Under the clinical diagnosis of recurrence, tissue excisions were conducted. Microscopically, the tissue was composed of bland spindle cells without cytological atypia, admixed with collagen bundles. Both tumours exhibited nuclear expression of β-catenin on immunohistochemical staining, which is a desirable criterion for desmoid fibromatosis., Discussion: Although positron emission tomography aids the diagnosis of recurrence, the radiological features of desmoid fibromatosis in computed tomography or magnetic resonance images are nonspecific and preoperative diagnosis of desmoid fibromatosis is difficult. The histological diagnosis of desmoid fibromatosis is difficult, especially when the specimen is small. The histological differential diagnosis of desmoid fibromatosis includes other myofibroblastic or fibroblastic tumours or lesions. Additional studies, such as β-catenin immunohistochemistry or CTNNB1 mutation analysis, can enable accurate diagnosis of desmoid fibromatosis. A correct diagnosis is essential, because the current therapeutic strategy is a "waitand- watch" approach, which is significantly different from those of the other locally aggressive, intermediate soft tissue neoplasms. We have summarised the clinicopathological, histological and immunohistochemical features of the post-operative desmoid fibromatosis.

Diarrhea is a common condition seen among soldiers in both garrison and deployed environments. Although the vast majority of soldiers with diarrhea will recover uneventfully with supportive care, clinicians should also maintain suspicion for less common causes and perform a thorough physical exam. We report the case of a young, healthy soldier with chronic diarrhea and progressively worsening abdominal distention that began during his deployment to Honduras who was subsequently found to have a large intra-abdominal desmoid tumor. Desmoid tumor is a rare and benign neoplasm that typically appears on the extremity, abdominal wall, intra-abdominal space, and occasionally in the chest wall. This tumor may be associated with abdominal distension and gastrointestinal complaints. A large tumor can compress organs, causing local tissue damage and, in rare cases, death., (© The Association of Military Surgeons of the United States 2021. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The treatment of choice for desmoid-type fibromatosis (DF) has been changed to active surveillance (AS). However, few studies have reported clinical outcomes of AS modality in Asian countries. This study aimed to clarify the significance of AS as a DF treatment modality., Methods: A total of 168 lesions from 162 patients with extra-abdominal DF were included. The mean age at diagnosis was 39 years (1-88 years), and the median maximum tumor diameter at the first visit was 64.1 mm (13.2-255.8 mm). The clinical outcomes of AS and the risk factors requiring active treatment (AT) (defined as an event) from AS modality were investigated., Results: Of the 168 lesions, 94 (56%) were able to continue AS, with a 5-year event-free survival of 54.8%. Of the 68 lesions with PD, 21 (30.9%) lesions were able to continue AS. Neck location (p = 0.043) and CTNNB1 S45F mutation (p = 0.003) were significantly associated with the transition to AT, and S45F mutation was a significant factor associated with the transition to AT by multivariate analysis (hazard ratio: 1.96, p = 0.048). AT outcomes after AS were evaluable in 65 lesions, and 49 (75%) lesions did not require a transition to a second AT., Conclusions: AS was revealed as an effective treatment modality. The transition to AT needs to be considered for neck location and CTNNB1 S45F mutation DF. Good results can be obtained by selecting a treatment method that considers the tumor location even in cases that require intervention., (© 2022 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

A 31-year-old Indian female with a history of near-total thyroidectomy 2.5 years prior presented with recurrent neck swelling. Magnetic resonance imaging (MRI) of the neck revealed an infiltrating mass involving the thyroid bed. Biopsy from the mass and review of slides from the previous thyroidectomy revealed a spindle cell tumour with interspersed areas of fibrosis and infiltrative edges entrapping thyroid follicles. Beta-catenin immunopositivity and CTNNB1 mutation confirmed the diagnosis of fibromatosis. The case is being reported for its rarity and the discussion of its differential diagnoses., Competing Interests: The authors declared no conflict of interest., (© 2023 Journal of the ASEAN Federation of Endocrine Societies.)

Introduction: Desmoid fibroma (DF) is a disorder characterized by strong clonal proliferation of myofibroblasts and fibroblasts. We describe a case of DF that mimicked a breast tumor, along with a review of the literature on the clinical manifestation, diagnostic process, and course of therapy for this combative disease., Case Report: A 34-year-old female patient with breast lump at the junction of the upper quadrants of the left breast. After the diagnosis of DF, it was decided to perform a sectorectomy of the left breast associated with post-quadrant reconstruction, with immunohistochemistry and findings compatible with DF., Discussion: Clinically manifests as a solid mass that is often painless and occasionally adherent to the chest wall. A treatment strategy should be idealized for each patient. Thus, there is the possibility of performing radical surgery for resection and/or radiotherapy, and surgery may be followed by radiotherapy.

Desmoid tumor is a rare tumor of the soft tissue. The frequency of occurrence is 2.4 to 4.3 cases per year per million people, which is a very rare disease. We experienced a huge intra-abdominal desmoid tumor which is thought to be the primary mesentery. The case was a male in his 20s. He visited a nearby doctor with a complaint of abdominal bloating and abdominal pain. Abdominal contrast CT revealed a huge abdominal mass with a clear boundary of 35×25 cm in size extending from the upper right abdomen to the pelvis. Surgery was performed with a diagnosis of an intra-abdominal mass. Open abdominal tumor resection. Due to infiltration into the duodenum, transverse colon, and pancreas, right hemicolectomy and duodenal combined resection were performed. The pathological diagnosis was a diagnosis of desmoid tumor.

Case Description: A 21-year-old healthy female presented with severe left lateral hip pain beginning suddenly two weeks prior. Physical examination revealed zero degrees of left hip external rotation passive range of motion with a firm end feel and pain severity and irritability out of proportion to an expected musculoskeletal presentation. She was referred to her physician with a recommendation for imaging to determine the source of pain and appropriateness of physical therapy., Outcome: Magnetic resonance imaging revealed a foreign mass in her left gluteus medius muscle which biopsy revealed to be a desmoid fibromatosis., Conclusion: This case demonstrates a thorough differential diagnostic process leading to medical imaging referral in a patient with a non-musculoskeletal source of pain. Physical therapists must be diligent in their differential diagnostic process to ensure appropriateness of their treatments or the need for referral.

Objective: Desmoid fibromatosis (DF) is a rare, locally aggressive soft tissue tumor. Computed tomography (CT) and magnetic resonance imaging (MRI) play a critical role in the diagnosis of DF and in developing treatment plans. Currently, observation is the primary therapeutic option for a biopsy-confirmed DF. Here, we present a case of a DF that was misdiagnosed as uterine fibroid before surgery., Case Report: A 36-year-old woman presented with urinary frequency and a palpable lower abdominal mass, which was suspected as uterine fibroid based on sonography and CT. During surgery, an abdominal wall mass was found to be densely adherent to the bladder. Permanent pathology revealed that the tumor was desmoid-type fibromatosis., Conclusion: Desmoid tumors often occur in the abdomen, abdominal wall, extremities, head, and neck. Abdominal wall DF involving the rectus abdominis muscles is most commonly observed. Conversely, desmoid tumors involving the bladder are less described. The review of similar cases reported since 1985 showed that partial cystectomy was primarily performed for complete resection., Competing Interests: Declaration of competing interest The authors have no conflicts of interest relevant to this article., (Copyright © 2023. Published by Elsevier B.V.)

A 71-year-old man with pathological Stage Ⅰ(pT1bN0M0)underwent laparoscopic sigmoid colon cancer resection. After 18 months postoperatively, follow-up computed tomography(CT)showed a 30 mm enhanced soft tissue tumor near the anastomotic site. Considering the magnetic resonance imaging(MRI)and positron emission tomography(PET)results, we diagnosed sigmoid colon cancer with local recurrence. Laparoscopic radical resection of the colon and intestine, including the tumor, was performed. Pathologically, the tumor comprised spindle-shaped cells with collagen fibers and was diagnosed as a desmoid tumor by immunostaining(β-catenin+, c-kit-, CD34-, α-SMA-, and DOG-1-). We report a case of intra-abdominal desmoid tumor near the anastomotic site after laparoscopic sigmoid colon cancer resection.

Desmoid fibromatosis is a rare connective tissue malignancy. It can occur in a variety of locations, including the abdominal wall, extremities and abdominal cavity. There has been an association with development in a prior surgical scar. Common symptoms can vary depending on the location and can include being painless to having pain at the site, functional impairment and bowel obstruction from intra-abdominal masses. In the following report, we discuss a case in which a patient's abdominal pain was attributed to a postoperative haematoma based on CT radiographic features; however, further work-up and biopsy yielded desmoid fibromatosis, a rare locally aggressive malignancy., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

BACKGROUND Desmoid tumor (DT), also known as aggressive fibromatosis or desmoid-type fibromatosis, is a rare disease. It can occur in anyone at any age, and is more likely to appear in female patients. DTs are sometimes associated with familial adenomatous polyposis and rare syndromes such as Gardner syndrome. Arising from specific cells, fibroblasts, they tend to develop in patients with a history of abdominal surgery and rarely produce metastases. CASE REPORT We present a case of a 41-year-old man who was referred for abdominal discomfort with no digestive or general symptoms. An abdominal CT scan revealed a mass in the left hypochondrium, corresponding to an intraperitoneal tumor extending to left colon. Based on MRI, we suspected a gastrointestinal stromal tumor. Colonoscopy showed no intraluminal tumor in the colon. A PET-CT scan revealed tumor hypermetabolism and no metastases. The mass was diagnosed as a DT after percutaneous biopsy. Six weeks after diagnosis and as the tumor continued increasing despite pharmacological treatment, the patient underwent surgical pancreatic tail resection with splenectomy and left colonic segmentectomy. Histological examination revealed a 7.047-g DT with severe infiltration of pancreatic parenchyma and transmural colic barrier, with no high-grade differentiation and negative resection margins. The postoperative recovery was uneventful, and we proposed surveillance with MRI. CONCLUSIONS The DT was surgically removed and patient remains under MRI surveillance. Other reported management approaches consist of radiotherapy, tyrosine kinase inhibitors, anti-hormonal therapies/non-steroidal anti-inflammatory drugs, chemotherapy, or close surveillance only. This is, to our knowledge, the largest and heaviest DT reported in the modern literature.

Desmoid fibromatosis (DF) is a locally aggressive soft tissue neoplasm with frequent recurrences. DF is characterized by alterations in the Wnt/β-catenin pathway, with the majority showing sporadic mutations in CTNNB1 , whereas others have germline mutations in APC . Immunohistochemical staining for β-catenin is often difficult to interpret and can be negative in up to 30% of cases. Prior studies have shown that some DFs lacking nuclear expression of β-catenin may carry activating CTNNB1 mutations. Droplet digital polymerase chain reaction (ddPCR) has been used effectively in detecting mutations in formalin-fixed, paraffin-embedded (FFPE) samples of various cancer types. In this study, we assess the diagnostic utility of ddPCR to detect CTNNB1 mutations in DF with β-catenin expression on immunohistochemistry (IHC), as well as in diagnostically challenging cases. Of the 28 DFs with nuclear β-catenin expression by IHC, 24 cases showed a CTNNB1 mutation by ddPCR using primers against the most common point mutations in CTNNB1 . The most frequent mutation was T41A (n=14; 50%), followed by S45F (n=8; 33%) and S45P (n=3;12%). We identified 8 additional (myo)fibroblastic lesions of uncertain classification, which were negative for nuclear β-catenin expression by IHC. We detected CTNNB1 mutations in 3 unknown lesions, including S45F (n=2) and S45P (n=1). ddPCR is a sensitive, rapid and cost-efficient methodology to detect common CTNNB1 mutations in DF, especially in diagnostically challenging cases., Competing Interests: The authors declare no conflict of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: This prospective nationwide cohort study aimed to investigate desmoid-type fibromatosis (DF) outcomes, focusing on the prognostic value of CTNNB1 mutations., Experimental Design: ALTITUDES (NCT02867033) was a nationwide prospective cohort study of DF diagnosed between January 2016 and December 2020. At diagnosis, CTNNB1 molecular alterations were identified using next-generation sequencing or Sanger sequencing. The primary endpoint was event-free survival (EFS; progression, relapse, or death). We enrolled 628 patients managed by active surveillance, surgical resection, or systemic treatment as first-line therapy., Results: Overall, 516 (82.2%) patients [368 females (71.3%), median age 40.3 years (range, 1-89)] were eligible for analysis. In 435 (84.3%) cases, there was one CTNNB1 molecular alteration: p.T41A, p.S45F, or p.S45P. The first-line management was active surveillance in 352 (68.2%), surgical resection in 120 (23.3%), and systemic treatments in 44 (8.5%) patients. CTNNB1 mutation distribution was similar across the three therapeutic groups. The median follow-up period was 24.7 (range, 0.4-59.7) months. The estimated 3-year EFS rate was 66.2% [95% confidence interval (CI), 60.5%-71.2%]. DF harboring p.S45F was significantly associated with male sex (P = 0.03), non-abdominal wall sites (P = 0.05), pain (P = 0.007), and large tumor size (P = 0.025). CTNNB1 p.S45F mutation was not significantly associated with EFS, either in univariate (HR, 1.06; 95% CI, 0.65-1.73; P = 0.81) or in multivariate analysis (HR, 0.91; 95% CI, 0.55-1.49; P = 0.71)., Conclusions: We found that CTNNB1 mutation profile was associated with unfavorable prognostic factors but was not a prognostic factor for EFS. See related commentary by Greene and Van Tine, p. 3911., (©2022 American Association for Cancer Research.)

Rationale: Desmoid-type fibromatosis is a rare benign mesenchymal neoplasm. Only 8% of desmoid-type fibromatosis develops in the abdominal cavity. The mesentery is seldom affected and gastrointestinal stromal tumors need to be considered in the differential diagnosis, particularly when imaging examination shows a tumor containing gases in the abdominal cavity. Only a few cases of gas-containing mesenteric desmoid-type fibromatosis have been reported in the literature., Patient Concerns: A 69-year-old male patient presented with hematochezia and intermittent upper abdominal pain., Diagnosis: Contrast-enhanced computed tomography revealed a 3.9 × 3.6 cm gas-containing mass infiltrating the third portion of the duodenum. The tumor was heterogeneous, with cysts and air bubbles. It showed heterogeneous weak-to-mild enhancement in the solid part. Postoperative pathological examination confirmed a final diagnosis of mesenteric desmoid-type fibromatosis., Interventions: The patient underwent surgical resection of intra-abdominal lesion., Outcomes: No evidence of local recurrence was noted during the 6 months of follow-up., Lessons: Accurate preoperative diagnosis is difficult for an intra-abdominal gas-containing mass on computed tomography scan. The appearance of spiculated infiltrative margin suggests the diagnosis of desmoid-type fibromatosis. Further investigation of imaging evidence and treatment methods is necessary., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Desmoid-type fibromatosis is a rare tumor, particularly in the orbit, with fewer than 10 cases of primary orbital desmoid-type fibromatosis reported in the literature. The authors present a case of an infant who presented with rapid onset of OD proptosis, disc edema, and hyperopic shift who was found to have a retrobulbar desmoid-type fibromatosis. After initial biopsy, due to risk of vision loss with complete excision, the tumor was treated with sorafenib, a tyrosine kinase inhibitor. During the course of treatment with sorafenib, the tumor stabilized and then regressed in size. To the authors' knowledge, this is the first reported case of orbital desmoid-type fibromatosis to be treated with sorafenib., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.)

Desmoid tumors (DTs) are rare soft tissue mesenchymal neoplasms that may be associated with impairments, disfigurement, morbidity, and (rarely) mortality. DT disease course can be unpredictable. Most DTs are sporadic, harboring somatic mutations in the gene that encodes for β-catenin, whereas DTs occurring in patients with familial adenomatous polyposis have germline mutations in the APC gene, which encodes for a protein regulator of β-catenin. Pathology review by an expert soft tissue pathologist is critical in making a diagnosis. Magnetic resonance imaging is preferred for most anatomic locations. Surgery, once the standard of care for initial treatment of DT, is associated with a significant risk of recurrence as well as avoidable morbidity because spontaneous regressions are known to occur without treatment. Consequently, active surveillance in conjunction with pain management is now recommended for most patients. Systemic medical treatment of DT has evolved beyond the use of hormone therapy, which is no longer routinely recommended. Current options for medical management include tyrosine kinase inhibitors as well as more conventional cytotoxic chemotherapy (e.g., anthracycline-based or methotrexate-based regimens). A newer class of agents, γ-secretase inhibitors, appears promising, including in patients who fail other therapies, but confirmation in Phase 3 trials is needed. In summary, DTs present challenges to physicians in diagnosis and prognosis, as well as in determining treatment initiation, type, duration, and sequence. Accordingly, evaluation by a multidisciplinary team with expertise in DT and patient-tailored management are essential. As management strategies continue to evolve, further studies will help clarify these issues and optimize outcomes for patients., (© 2022 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Desmoid fibromatosis is a rare disease caused by genetic alterations that activate β-catenin. The tumors were previously treated with aggressive surgeries but do not metastasize and may regress spontaneously. For these reasons, in the absence of symptoms and when growth would not induce significant complications, active observation is considered first-line therapy. When intervention is required, surgery can be considered based on anatomy and risk of postoperative recurrence, but increasingly nonoperative therapies such as liposomal doxorubicin or sorafenib are prescribed. Cryoablation, chemoembolization, and high-intensity focused ultrasound can also be used to obtain local control in selected patients., Competing Interests: Disclosure K. Prendergast – nothing to disclose S. Kryeziu – nothing to disclose A.M. Crago – advisory board, Springworks Therapeutics., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Meckel's diverticulum (MD) is among the many known congenital malformations of intestine. It is seen in approximately 2% of the population. Desmoid tumors are unusual. They are unique, well-differentiated, and fast-growing musculoaponeurotic fibromatosis tumors, contemplated as Grade 1 fibro sarcoma. They offer exclusive management challenges to surgeons. The most common presentation of desmoid tumors is of painless masses with sluggish growth. Rarely, they may present as intestinal obstruction leading to surgical emergency. We present the only case in history till date along with review of the relevant literature of a 65-year-old gentleman who presented to us with features of intestinal obstruction who successfully underwent elective segmental resection of ileum containing MD with its desmoid tumor. A multimodality approach is needed to tackle such kind of diseases with a team comprising oncosurgeons, oncophysicians, and radiation oncologist to design a standard treatment protocol., Competing Interests: None

Background: Mesenteric fibromatosis is a benign locally-aggressive mesenchymal neoplasm that lacks the potential for metastasis. It is related to Gardner's Syndrome, previous trauma, abdominal surgery, and prolonged intake of oestrogen. Differentially diagnosing this from similar tumours is crucial in order for establishing the appropriate treatment and only immunohistochemical features can be used for a definitive diagnosis. Although medical therapies play a role in the treatment of mesenteric fibromatosis, surgical resection is the gold-standard procedure., Methods: Our case study is a 40-year-old male with a concomitant diagnosis of non-Hodgkin lymphoma and mesenteric fibromatosis, not associated with any of the risk factors mentioned above. We performed CT and PET scans and observed a vascularised and well-defined mesenteric centre-abdominal hypermetabolic solid mass in contact with the gastric body, duodenum, body and tail of the pancreas, transverse colon, and spleen. An ultrasound-guided tru-cut biopsy revealed features suggestive of mesenteric fibromatosis., Results: An elective laparotomy was carried out and a giant mass, arising from mesentery, was excised, including a partial gastrectomy and segmental resection of the transverse colon. Distal pancreatectomy, small bowel resection and successive splenectomy were performed due to a large hypertensive component. The postoperative period was uneventful. The histopathology of the surgical pieces was compatible with intra-abdominal desmoid fibromatosis., Conclusion: As far as we know from the literature, this is the largest mesenteric fibromatosis tumour ever to be excised. We also noticed that this is the first reported case of the concomitant presence of mesenteric fibromatosis and non-Hodgkin lymphoma that is not related to any of the described risk factors. Further research is needed to establish what type of association this presentation may indicate.

Introduction: Desmoid tumor (DT) of the abdomen is a challenging and rare disease. The level of evidence available to document their treatment is relatively low, however, recent publications of prospective studies have allowed to precise their management., Methods: This document is a summary of the French intergroup guidelines realized by all French medical and surgical societies involved in the management of DT located in the abdomen or associated with adenomatous polyposis. Recommendations are graded in four categories (A, B, C and D), according to the level of evidence found in the literature until January 2021., Results: When the diagnosis of DT is suspected a percutaneous biopsy should be performed when possible. A molecular analysis looking for pathogenic mutations of the CTNNB1 and APC genes should be systematically performed. When a somatic pathogenic variant of the APC gene is present, an intestinal polyposis should be searched. Due to a high rate of spontaneous regression, non-complicated DT should first benefit from an active surveillance with MRI within 2 months after diagnosis to assess the dynamic of tumor growth. The treatment decision must be discussed in an expert center, favoring the less toxic treatments which can include broad spectrum tyrosine kinase inhibitor or conventional chemotherapy (methotrexate-vinblastine). Surgery, outside the context of emergency, should only be considered for favorable location in an expert center., Conclusion: French guidelines for DT management were elaborated to help offering the best personalized therapeutic strategy in daily clinical practice as the DT therapeutic landscape is complexifying. Each individual case must be discussed within a multidisciplinary expert team., Competing Interests: Declaration of Competing Interest O. Bouché: Roche, Merck, Amgen, Servier, Pierre Fabre, Bayer, Grunenthal. C. Le Pechoux: Institutional honoraria for participation to boards or scientific meetings: Amgen, Astra Zeneca, Lilly, Medscape, Nanobiotix, PrimeOncology, Roche. NB: Conference fees: Tillots Pharma, Travel grants: Pfizer. The other authors have reported no potential conflicts of interest., (Copyright © 2022 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Background: Abdominal fibromatosis presenting as an abdominal mass is a rare occurrence in a gynecological setting. The diagnosis might not be suspected preoperatively, and management could be challenging., Case: An 18-year-old girl with ovarian germ cell malignancy was managed with staging laparotomy and chemotherapy. She developed a large abdominal mass 10 months later. An abdominopelvic mass (40 × 20 cm) was removed at laparotomy. The histopathological diagnosis was intra-abdominal fibromatosis. A rapidly growing abdominal mass recurred postoperatively. After discussion with the tumor board, chemotherapy with methotrexate and vinblastine was started. The tumor was not responsive, and the patient succumbed after the second cycle of chemotherapy., Summary and Conclusion: Abdominal fibromatosis should be considered among the differential diagnoses of a rapidly growing abdominal mass after resection of an ovarian germ cell tumor., Competing Interests: Declaration of Competing Interests There are no conflicts of interest for any of the authors., (Copyright © 2022. Published by Elsevier Inc.)

Desmoid-type fibromatosis (DF) is a distinctly rare condition, mostly of younger adults, characterized by the development of locally aggressive tumors of mesenchymal origin. Desmoid tumors (DT) arise either sporadically or in association with FAP (familial adenomatous polyposis), although certain risk factors have also been identified, including pregnancy and antecedent surgical trauma. They can emerge from any connective tissue including muscle, fascia and aponeurosis and are therefore classified, according to location, as intra-abdominal, of the abdominal wall and extra-abdominal. Despite the lack of metastasizing potential, the course can be unpredictable. Various mutations of APC and β-catenin genes, among others, play a catalytic role in the pathogenesis of this neoplastic entity. Surgery has lost its traditional role as first line treatment of the disease and several other treatment methods are being considered. Cytotoxic chemotherapy, non-cytotoxic systemic therapy and targeted therapy have been revealed as part of different treatment regimens. Recent progress regarding DT biology and molecular pathways has led to the development of promising novel biological agents. In any case, a multidisciplinary approach is required and is gradually employed, espe-cially in intra-abdominal DTs. In this review, we aim to present current knowledge on DF and summarize current treatment regimens as well as their effectiveness, with emphasis on the intraperitoneal type of DT., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Introduction/aim: The epidemiology, demographic, clinical, treatment, and healthcare resource utilization (HRU) characteristics of desmoid tumor (DT) patients treated at two sarcoma centers in Denmark is described., Methods: Using Danish health registers, we studied DT patients treated at two sarcoma centers between 2009 and 2018. For each patient, ten persons from the general population were randomly matched on birth year, sex, and region of residence., Results: Of the 179 DT patients identified, 76% were female and the median patient age was 38 years at diagnosis (interquartile range: 31-50). An average annual incidence of DTs over the study period was 3.2 per 1000,000 individuals with the observed annual incidence of DTs ranging from 2.2 (2011) to 4.3 (2017) per 1000,000 individuals. No notable linear time trend in incidence was observed. Anatomical DT sites included extra-abdominal (49%), abdominal wall (40%), and intra-abdominal or retroperitoneal areas (8%). In total, 56% of patients were initially treated surgically. However, while 75% of patients diagnosed with DT between 2009 and 2014 were initially treated surgically, this was true for only 32% of patients diagnosed with DT between 2015 and 2018. A total of 56% of DT patients used chemotherapeutic agents, tyrosine kinase inhibitors, NSAIDs, opioids, antidepressants, or steroids at some point during the three years before their DT diagnoses. In contrast, 70% of surgically treated and 63% of non-surgically treated patients used one of these drugs in the subsequent three years, including NSAIDs (45% surgical vs. 33% non-surgical), opioids (39% surgical vs. 27% non-surgical), and steroids (22% surgical vs. 18% non-surgical). The average number of inpatient and outpatient visits, days of hospitalization, and additional surgical procedures were higher among DT patients than the comparison cohort., Conclusion: DTs are rare but have a large impact on patients' health, HRU, and medication utilization., (Copyright © 2022 Elsevier Ltd. All rights reserved.)