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Calcifying fibrous tumors are rare benign fibrous tumors that rarely occur in the heart. We report a 33-year-old woman who was found to have a benign pericardial tumor on health checkup, which was highly suspected to be a teratoma in clinical and imaging examination. After cardiac tumor resection, histopathological features showed scattered foci of psammoma bodies or calcification among collagenized fibrous connective tissues and foci of inflammatory cell infiltration in the interstitium. The pathological diagnosis was a calcifying fibrous tumor., 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.

Superficial CD34 positive fibroblastic tumor is a rare low-grade neoplasm of the skin and subcutis with indolent behavior. This entity has been included in the current World Health Organisation (WHO) classification of soft tissue tumors. Pathological diagnosis can be challenging due to significant morphological overlap with other entities and the large spectrum of CD34 positive tumors. We report a case in a twenty-five male which showed characteristic diagnostic features, but in addition showed myxoid stroma. The presence of myxoid stroma has not been previously emphasized in this entity and broadens the histologic differential diagnosis significantly to include myxoid soft tissue tumors. A subset of these tumors harbor PRDM10 -rearrangements, but a defining molecular feature has not yet been described, highlighting the need for further molecular characterization of this potentially genetically heterogenous tumor. Awareness of this entity among surgeons and pathologists is important to prevent misclassification as an aggressive sarcoma and avoid over-treatment.

Objective: To investigate the clinicopathological features, immunophenotypic and molecular genetic characteristics and differential diagnosis of fibrous hamartoma of infancy (FHI). Methods: Thirty-three cases of surgically removed FHI were collected from the Department of Pathology, Henan Provincial People's Hospital from October 2011 to December 2020, the clinical and pathologic data with follow-up were collected and analyzed. Next-generation sequencing (NGS) and quantitative real time polymerase chain reaction (q-PCR) were used to study the molecular genetics. Results: The FHI cases occurred in 21 males and 12 females (mean age 16.7 months, range 6 months to 6 years). The sites included trunk ( n =21), limb ( n =11), and neck (n =1). All patients had painless solitary superficial soft tissue masses, the size was 1.5-9.0 cm (mean 3.8 cm). Microscopically, they were composed of mature adipose tissue, fibroblast/myofibroblast bundle and primitive mesenchymal cells in different proportions; giant cell fibroblastoma-like areas were seen in 14 cases. Immunohistochemistry showed variable expression of EGFR in the spindle cells and primitive mesenchymal components. In most cases, the spindle cells were positive for CD34 and SMA; giant cell fibroblastoma-like areas were strongly positive for CD34; and S-100 protein was expressed by adipocytes in all cases. Ki-67 labeling index ranged 1%-5%. There were recurrent somatic EGFR exon 20 insertion/duplication mutations in six cases tested by NGS, and there were three different mutation types: p.Asn771_His773dupAsnProHis, p.Pro772_His773insProProHis, and p.His773_Val774insThrHis. All the above 6 and another 15 tested cases showed EGFR exon 20 insertion/duplication mutations by q-PCR. Conclusions: FHI is a rare benign fibroblast/myofibroblast tumor. The characteristic histologic feature is organoid triphasic morphology, and the molecular feature is somatic mutation of EGFR exon 20 (insertion/duplication).

Superficial CD34-positive fibroblastic tumor (SCPFT) is a recently described entity that, despite significant pleomorphism, carries a good prognosis. We briefly describe this tumor and its principal differential diagnoses. Recognition of SCPFTs, including the clinical context in which they arise, is important to avoid confusion with other pleomorphic soft tissue tumors, particularly neoplasms in the group of pleomorphic sarcomas, which are typically aggressive tumors that could lead to unnecessary overtreatment.

Competing Interests: Competing interests: None declared.

Rationale: Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma. Owing to the lack of specific histological criteria, immunohistochemical, and molecular diagnostic markers, several differential diagnoses must be considered. Advances in molecular testing can provide significant insights for management of rare tumor., Patient Concerns: The patient was a 50-year-old man with a history of lumpectomy on the right back 30 years ago. He felt a stabbing pain at the right iliac fossa and went to the local hospital., Diagnosis: By immunohistochemistry, the tumor cells stained positively for S-100 (focal +), CD34 (strong +++) and Ki-67 (20%), and negatively for smooth muscle actin, pan-cytokeratin, neurofilament, pan-cytokeratin-L, GFAP, CD31, STAT6, ERG, myogenin, and MyoD1. Combined with the histopathology and immunohistochemistry results, our initial diagnosis was solitary fibrous tumor (SFT) or MPNST. The tissue biopsy was sent for next-generation sequencing. neurofibromatosis type 1 Q1395Hfs*22 somatic mutation, neurofibromatosis type 1 D483Tfs*15 germline mutation, and amplifications of BTK, MDM2, ATF1, BMPR1A, EBHA2, GNA13, PTPN11, RAD52, RPTOR, and SOX9, as well as TJP1-ROS1 fusion, CDKN2A-IL1RAPL2 fusion and CDKN2A/UBAP1 rearrangement were identified. Given that NAB2-STAT6 fusion, a specific biomarker of SFT, was not identified in our patient's tumor, the SFT was excluded by through genetic testing results. Therefore, our finally diagnosis was a MPNST by 2 or more pathologists., Interventions and Outcomes: Subsequently, the patient received crizotinib therapy for 2 months and showed stable disease. However, after crizotinib continued treatment for 4 months, the patient's disease progressed. Soon after, the patient stopped crizotinib treatment and died in home., Lessons: To our knowledge, this is the first report of the TJP1-ROS1 fusion, which expands the list of gene fusions and highlights new targets for targeted therapy. Also, our case underlines the value of multi-gene panel next-generation sequencing for diagnosis of MPNST.

Aims: Calcifying fibrous tumor (CFT) is a very rare begin fibroblastic tumor featuring a widely anatomical distribution and may mimic various spindle cell tumors. Misdiagnosis and hence mistreatment are likely caused due to unfamiliarity to clinicians or junior pathologists. We collected a relatively large series of CFTs in our institution aiming at further summarizing their clinicopathologic features in Chinese patients and discussing the diagnosis and differential diagnosis in clinical practice., Methods: Clinicopathologic data of 22 CFTs were retrospectively reviewed. Histologic features were reevaluated and summarized. Immunostaining markers include CD34, SMA, Desmin, keratin, S100, ALK1, CD117, IgG, IgG4, and Ki-67. Follow-up of all cases was performed., Results: 22 CFTs include gastric (n=8), pulmonary (n=2), hepatic (n=2), cervical (n=1), appendiceal (n=1), esophageal (n=1), retroperitoneal (n=1), intra-abdominal (n=1), diaphragmatic (n=1), spermatic cord and scrotum (n=1), anconeal (n=1), mesenteric (n=1), and omental (n=1) lesions. Coexisting hepatocellular carcinoma, pancreatic carcinoma, pheochromocytoma, Castleman disease, and leiomyoma of the uterus and other metabolic or functional disorders were also appreciated. CFT histologically features spindle cells embedded dense hyalinized stroma with scattered psammomatous calcifications and lymphoplasmacytic infiltration and immunohistochemically for CD34. None of any individuals die of CFT per se., Conclusion: Our study discloses that CFT is a bona fide benign fibroblastic lesion, regardless of its developing location. Involvement of digestive tract seems much more common in the Chinese population. Awareness of the clinicopathologic characteristics of this rare entity and its mimickers contribute to avoiding misdiagnosis and mistreatment in clinical practice.

Atypical fibroxanthoma (AFX) is a dermal spindle-cell sarcoma that is considered a superficial and clinically benign presentation of pleomorphic dermal sarcoma, malignant fibrous histiocytoma, and undifferentiated pleomorphic sarcoma. AFX appears clinically as a discrete red or pink nodule or papule, most commonly on the head and neck region of sun-damaged elderly patients. Histologic findings on routine hematoxylin and eosin staining reveal spindle-shaped, large, and pleomorphic tumor cells throughout the dermis. Immunohistochemistry is not specific for AFX, and the diagnosis is generally one of exclusion. AFX is best treated by complete surgical excision, with Mohs micrographic surgery considered the treatment of choice. Metastasis rarely occurs, but there is a high rate of local recurrence, especially in patients who are immunosuppressed., (©2019 Frontline Medical Communications.)

Fibroblastic and myofibroblastic tumors comprise a morphologically diverse and biologically variable group of neoplasms that affect a wide age range. Specific entities tend to occur most frequently in infants and young children. Recent years have witnessed a proliferation of information concerning the unique biology of these tumors. In this report, I will review recent findings that serve to further characterize this group of neoplasms. Included will be newer information on fibrous hamartoma of infancy, infantile myofibromatosis, lipofibromatosis, and infantile fibrosarcoma and tumors resembling it, including primitive myxoid mesenchymal tumor of infancy and new genetic entities. I will also discuss the differential diagnosis, which includes spindle cell rhabdomyosarcoma, dermatofibrosarcoma protuberans, and calcifying aponeurotic fibroma., Competing Interests: No competing interests were disclosed.No competing interests were disclosed.No competing interests were disclosed.

Rationale: Calcifying fibrous tumors ("CFT") are recognized as extremely rare mesenchymal tumors with benign biological behavior and low rates of recurrence are seen after removal. The first case of a CFT was reported in 1988 as a possibly inflammatory triggered pseudotumor in deep soft tissue of children. Histologically, the tumor is typically composed of dense hyalinized collagen with paucicellular infiltration of lymphocytes and fibroblasts as well as psammomatous or dystrophic calcifications. It can affect soft tissue in very different anatomical locations, also intrathoracic and intra-abdominal, mimicking various different diagnoses. The etiology is understood to be unclear. Asymptomatic CFTs can be found incidentally on medical images., Patient Concerns: We present the case of a calcifying tumorous lesion found incidentally in the mesentery of the terminal ileum of a 34-year-old male patient in February 2016 undergoing a computed tomography for a urinary tract infection., Diagnosis: Histopathological and immunhistochemical examination after surgery revealed a CFT., Interventions: Our patient underwent lower abdominal median laparotomy for tumorectomy., Outcomes: Two years after surgery the patient is free of a recurrence., Lessions: We add another case of intra-abdominal CFT to medical literature to provide more information about this very seldom tumor. While the etiology of CFT should be further investigated, diagnosis and therapy seem clarified. CFT should be kept in mind as a rare differential diagnosis of calcifying tumors also in the abdominal cavity. Immunohistological work-up is important for finding the diagnosis and may also help solving pathogenetical questions.

Calcifying fibrous tumor of the pleura (CFTP) is a rare mesenchymal tumor of unknown pathogenesis. The diagnosis often requires exclusion of other common entities. Our aim was to determine if genomic changes were associated with CFTP that could contribute to mechanisms underlying tumorigenesis. Three cases of CFTP with their corresponding uninvolved control lung tissue were identified. Two patients were male, and 1 was female (age range, 21-32 years). Tumors were multifocal in 2 cases and solitary in 1. Immunohistochemistry for STAT6, BCL-2, CD34, cytokeratin AE1/AE3, calretinin, desmin, S100, ALK, and β-catenin was used. All immunohistochemistries were negative in CFTPs. DNA was isolated from all 3 pairs of CFTPs and matching normal lungs for whole-exome sequencing. Damaging, tumor-specific, coding variants were identified in 3 genes including multiple heterozygotic, de novo mutations in the Zinc Finger Protein 717 (ZNF717), fascioscapulohumeral muscular dystrophy-1 (FRG1) and cell division cycle 27 (CDC27) genes. Whole-exome sequencing revealed statistically significant, focal, tumor-specific copy number losses among all CFTPs including a large (302 kb) loss at 6p22.2 comprising 32 genes of the histone cluster 1 family and the hemochromatosis (HFE) gene. This is the first study to evaluate the molecular pathogenesis of CFTP and to identify novel deleterious mutations in ZN717, FRG1, and CDC27 genes as well as significant copy number losses on 8 chromosomes with a large loss common to all samples on chromosome 6. These mutations deleteriously altered coding domains in a manner predicted to be damaging to protein function and may contribute to CFTP tumorigenesis., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: Paratesticular fibrous pseudotumor (PFP) represents a benign tumor-like lesion confined to intrascrotal, paratesticular areas. Due to its rarity, only less than 200 cases have been reported to date, of which both pathogenesis and clinical management are little understood. Recently, PFP has been postulated to be among the spectrum of so-called immunoglobulin G4-related diseases (IgG4-RD). Here we describe a case of PFP focusing on the clinical, morphological features and the utility of immunohistochemistry to support the theory that PFP might be a potential member of IgG4-RD family., Case Presentation: A 41-year-old man presented with a slowly growing, right intrascrotal mass An MRI scan revealed a diffuse-proliferative nodular mass around the paratesticular area. The patient underwent right orchiectomy and a diffuse multinodular tumor with testicular compression was discovered without intratesticular infiltration. Postoperatively, the patient has been well for 2 years up to the recent follow up. On histological examination, the lesion consisted of hyalinized fibrotic tissue with storiform patterns. There were scattered germinal centers; lymphocytic vasculitis was also noted. The immunoglobulin G4 staining showed infiltration of positive plasma cells with highest count 52 per high-power field, whereas the mixed Kappa and Lambda immunoglobulin light chain expression indicated the polyclonality of the plasma cell population., Conclusions: The morphological and immunohistochemical features in our case support the theory of PFP being part of IgG4-RD. Familiarity to this tumor-like lesion is crucial, since it may respond to corticosteroid therapy, which may save patients from more aggressive surgical procedures., (© 2018 by the Association of Clinical Scientists, Inc.)

Myxoinflammatory fibroblastic sarcoma is a rare soft tissue tumor with most occurring in the distal extremities of adult patients. It has a high rate of local recurrence and a low rate of metastasis. Because it may appear benign on clinical examination, and because the microscopic features are generally underrecognized, it is often inadequately treated and misdiagnosed. In this review, based upon experience and that of the literature, the intent is to highlight salient clinicopathologic features, detail the broad microscopic spectrum including high-grade aggressive variants, review the molecular features, and discuss its relation to hemosiderotic fibrolipomatous tumor.

Rationale: Calcifying fibrous tumor (CFT) is a rare benign soft tissue mesenchymal neoplasm. Although the gastrointestinal (GI) tract is the most common predilection site of CFT, the clinicians, even including pathologist, generally consider it as GI stromal tumor (GIST) or other submucosal tumors such as schwannoma and leiomyoma., Patient Concerns: A 55-year-old man presented with complaints of epigastric discomfort and abdominal distention for more than 1 year., Diagnoses: On the basis of endoscopic and computed tomography examination, preliminary diagnosis was GIST., Interventions: Endoscopic submucosal dissection (ESD) surgery was performed to remove the gastric mass., Outcomes: The histopathological examination revealed a gastric CFT., Lessons: We present a case of gastric CFT, which was misdiagnosed as GIST based on endoscopic and radiologic findings., (Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To investigate the clinical features, immunohistochemical and differential diagnosis of desmoplastic fibroblastoma. Methods: The clinical data and pathology features of 7 cases of desmoplastic fibroblastoma were collected and immunohistochemical study were carried out in all cases with a review of the literatures. Results: There were 2 males and 5 females, with age ranging from 31 to 71 years (average and mean age were 59 and 61 years, respectively). The tumors were located in extremities and abdomen (left toe and right toe, right foot back, left leg and right thigh, right forearm and left hepatic lobe). Clinically, the tumors presented as slow growing painless masses of long standing duration. Grossly, the tumors were well-circumscribed with firm, white to gray cut-off surface. Tumor size ranged from 1.2 to 4.0 cm in maximum diameter (average 3.0 cm). Microscopically, 2 cases were located in dermis, 4 cases were located in subcutaneous and 1 case was located in liver parenchyma. It was composed of spindle-shaped or stellate cells with a fibroblastic or myofibroblastic appearance, and sparsely scattered in densely fibrous or fibromyxoid background. There was small vascular component in tumor background. At high magnification, the tumor cells were medium size with abundant cytoplasm, and the nucleus were small and always with small nucleoli. In some cases, the tumor cells were slightly larger with enlarged nuclei, but without cellular atypical and mitosis. Immunohistochemical study showed that the tumor cells were strongly positive for vimentin, desmin, S-100 protein and CD34, but CKpan was negative. α-SMA showed focal positive in one case. Ki-67 index ranged from 1% to 2%. Four cases were followed-up (ranged from 11 to 21 months, average 16.5 months) and the patients had no recurrence after surgery. Conclusions: Desmoplastic firoblastoma is a rare soft benign tumor. The differential diagnosis includes other benign or low-grade fibroblastic/myofibroblastic lesions.

Objective: To improve the clinical diagnosis and treatment of calcifying fibrous tumor (CFT) of the tunica vaginalis testis, we discussed clinical manifestations and pathologic features of CFT., Materials and Methods: A retrospective analysis of 2 cases of CFT that occurred in our hospital was performed, and we also reviewed the literature and research reports., Results: Both patients underwent local excision with testis preservation surgery, and pathology examination confirmed the presence of multiple CFTs of the tunica vaginalis testis., Conclusion: CFTs are rare, benign multiple lesions, and the recognition of which needs to be improved to avoid overtreatment. We are the first to describe 2 cases of CFT combined with hepatitis B, but additional studies are needed to confirm the relationship between these conditions., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To investigate the value of combined application of MDM2, CDK4 and SATB2 immunohistochemistry in pathological diagnosis of low-grade osteosarcoma., Methods: Forty-seven cases of low grade osteosarcoma, including low grade central osteosarcoma (n=20) and parosteal osteosarcoma (n=27), were selected from Shanghai Jiaotong University Affiliated the Sixth People's Hospital. The clinical, radiography and histopathology were reviewed. The sensitivity and specificity of MDM2, CDK4 and SATB2 immunohistochemistry in the diagnosis of low-grade osteosarcoma were assessed along with an evaluation of their expressions in fibrous dysplasia, desmoplastic fibroma, low-grade fibrosarcoma and other fibrous tumors., Results: Low-grade osteosarcoma had protracted clinical course, occurring mostly in elder adults and mainly involving long bones. Radiographic studies showed that low-grade central osteosarcoma had a mainly malignant lytic presentation, however about 5/18 of tumors overlapping with intermediate and benign bone diseases, while parosteal osteosarcoma was characterized by a densely sclerotic malignant appearance. Histologically, low-grade osteosarcomas were characterized by well-differentiated spindle tumor cells, various mature tumor bones and an aggressive growth pattern. The positive expression rates of MDM2 and CDK4 in low-grade osteosarcoma were 74.5% and 55.3%, respectively. Eighty-three percent of low-grade osteosarcoma expressed one or both markers. Low-grade osteosarcoma and fibrous dysplasia were both positive for SATB2, while desmoplastic fibroma, low-grade fibrosacoma and other fibrous tumors were negative for SATB2., Conclusions: Accurate diagnosis of low-grade osteosarcoma should be based on combination of clinical presentation, imaging and histopathology, with immunohistochemistry as a diagnostic adjunct. Positive immunostaining for CDK4 and/or MDM2 supports the diagnosis of low-grade osteosarcoma, but the negative one does not rule out such lesion. The negative expression of SATB2 is helpful to exclude fibrous tumors originating from bone with the exception of fibrous dysplasia.

Calcifying fibrous tumor (CFT) is a benign lesion characterized by its specific histological findings and is found as solitary or multiple lesions in several locations of the human body. The aim of the present systematic review is to give a detailed account of all reported cases of CFT in the literature and to analyze the available data, to completely characterize the entity from epidemiological, medical, and surgical aspects.A bibliographic research was performed from 1988 until 2015. A database with the patients' characteristics was made, including sex, age, location of the tumor, symptoms, symptoms duration, size of the tumor, diagnostic methods, treatment, metastasis, and follow-up.A total of 104 articles were identified, reporting 157 cases of CFT. Mean age of patients was 33.58 years and the ratio between men and women was 1:1.27. The most common locations of CFT were stomach (18%), small intestine (8.7%), pleura (9.9%), mesentery (5%), and peritoneum (6.8%). Mean diameter of the tumor was estimated 4.6 cm. The correlations proceeded showed that as age increases, size decreases (P = 0.001) and that the tumor is larger in females (P = 0.027). Kruskal-Wallis test showed that the larger tumors appear in the neck and adrenal gland (P = 0.001). The percentage of asymptomatic patients was 30.57%. Computed tomography and biopsy were the most common tests for the diagnosis of CFT. Open surgical procedure was performed in the majority of cases. The median hospitalization was 6.06 days and the mean follow-up period was 29.97 months. Recurrences were mentioned in 10 of 96 patients with available data. No deaths owing to CFT were mentioned in the literature.CFT should be included in the differential diagnosis of enlarging mass revealed by clinical or imaging examination either incidentally or after specific acute or chronic symptomatology.

Calcifying fibrous tumor is a rare soft tissue benign tumor (OMS 2002). Some pleural localisations are described, which affect slightly older individuals than the other soft tissue forms. The calcifying fibrous tumor is included in the 2004 World Health Organization classification of pleural tumors. A pleural tumor located in the right inferior pulmonary lobe is diagnosed in a 59-year-old man. This pleural tumor is macroscopically well-circumscribed. Histologically, the rare spindle tumoral cells are located between bundles of a collagenous tissue, sometimes hyalinized, with psammomatous or dystrophic calcifications. The tumoral cells have a fibrohistiocytic origin. They stain positively for antibodies against vimentin, factor XIIIa, CD68, CD163, CD34. Antibodies against smooth muscle actin, desmin, PS100, ALK1 and EBV are negative. Main differencial diagnoses are other benign pleural tumors (solitary fibrous tumor, inflammatory myofibroblastique tumor), some malignant tumors (desmoplastic malignant pleural mesothelioma) and pleural pseudotumors (calcified pleural plaques, chronic fibrous pleuritis, amylose, hyalinizing granuloma). Our case is the 15th pleural calcifying fibrous tumor being reported., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

The spectrum of clinical presentations in pediatric skin and soft-tissue lesions often makes diagnosis challenging. Delays in diagnosis and subsequent treatment can be life threatening, and they can subject patients to more complicated reconstruction. This retrospective case series reviews the presentation, management, and current literature on eight pediatric skin and soft-tissue lesions. For rare lesions and those with unclear pathology, a multidisciplinary approach is strongly advocated for optimal management., (Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.)

Gastrointestinal lesions resulting from immunoglobulin G4-related disease are classified into two types: One is a gastrointestinal lesion showing marked thickening of the wall, and the other is an IgG4-related pseudotumor. We report the case of a woman with gastric calcifying fibrous tumor undergoing endoscopic resection that contained 62 IgG4+ plasma cells per high-power field and an IgG4-to-IgG ratio of 41% in lesional plasma cells, which shared clinical and histopathological features associated with gastric IgG4-related pseudotumor. So, we postulate that calcifying fibrous tumor as part of the spectrum of IgG4-related disease might be the unifying concept with IgG4-related pseudotumor. Meanwhile, the patient had coexistent autoimmune diseases, including autoimmune atrophic gastritis, Hashimoto's thyroiditis, and possible primary biliary cirrhosis. The clinical follow-up evaluation was uneventful.

Acquired periungual fibrokeratomas are benign fibrous tissue tumors and are considered as the topographical variant of acquired digital fibrokeratoma. They usually present as solitary tumors. In some instance, the entity may appear in multibranched fashion. The main histopathologic features consist of acanthosis, thick collagen bundles mainly oriented in a vertical axis forming a central core, and numerous proliferating fibroblasts. In this article, we present two cases of acquired multibranched periungual fibrokeratoma and depict their varying clinical features over time. Binucleation and perinuclear halos of keratinocytes mimicking human papillomavirus (HPV) infection were detected microscopically, but there was no reactivity with HPV immunostaining. In context, anti-HPV immunostaining may be helpful in the differentiation of fibrokeratomas from HPV infection. On the other hand, it should be kept in mind that these histopathologic findings may be found in acral biopsies independent of viral effects., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Fibrous, myofibroblastic, and fibrohistiocytic soft-tissue tumours are amongst the most common benign soft-tissue lesions encountered in clinical practice. They demonstrate varied biological behaviour and imaging characteristics. Benign fibroblastic lesions, such as nodular fasciitis, are small, have a self-limited course, and rarely recur after excision, whereas deep fibromatosis and plexiform fibrohistiocytic tumours tend to exhibit more aggressive features and often have high recurrence rates. MRI with its superior tissue contrast, multiplanar imaging capability, and lack of ionising radiation is regarded as the preferred method of tumour evaluation, tissue characterisation, and assessment of treatment response. Histopathological features are depicted at MRI, reflecting the amount and distribution of the cellular and fibrous matrix. Cellular tumours tend to show higher T2 signal intensity and post-contrast enhancement as compared to tumours with greater collagenous content, which appear dark and show less enhancement. Awareness of MR characteristics, pathological behaviour, and common sites of occurrence of fibrous soft-tissue tumours will help radiologists to determine the appropriate differential diagnosis and guide patient management., (Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Clear cell proliferations of the skin consist of a diverse group of lesions characterized by the presence of cells with abundant clear cytoplasm. They may arise from primary, metastatic, or non-neoplastic origins, with their distinctive cytoplasmic clearing attributable to causes ranging from artifact to accumulation of materials such as glycogen, mucin, or lipids. Despite the heterogeneity of these lesions, their distinguishing characteristics may be subtle, especially at high power. As such, histologic diagnosis can be challenging, and proper consideration relies on an understanding of the scope of possible origins, etiologies, and key immunohistochemical staining patterns of the various entities. This review categorizes cutaneous clear cell neoplasms by histogenesis, and offers differential diagnostic strategies to aid in their clinicopathologic evaluation.

Calcifying fibrous tumors (CFT) are rare benign tumors. They usually affect children and young adults and the incidence is equal in males and females. The usual clinical presentation is that of a painless mass. A computed tomography scan typically reveals a well-demarcated calcified lesion. CFT usually presents as a solitary mass and the commonest sites of occurrence are in soft tissues, the pleura, or the peritoneum. Multifocal occurrences at the same site have also been reported. The first case of CFT was reported in 1988. We present a rare case of multiple calcifying fibrous tumors at multiple sites in the same patient. To the best of our knowledge, this is the first ever reported case of multifocal CFT atsix different anatomical sites in one patient.

Calcifying fibrous tumor (CFT) is a recently recognized rare benign lesion characterized by dense hyalinized collagenous tissue with interspersed spindle cells and a lymphoplasmocytic infiltrate. Calcification is the hallmark of CFT and may present in the form of psammomatous bodies or dystrophic calcifications. CFT of the intestinal tract is uncommon and rectal CFT has never been reported. Recently, we experienced a case of CFT found in the rectum of a 36-year-old man. In this study, we described the characteristic histopathological findings with a review of the relevant literature. Although CFT of the intestinal tract as an intrinsic visceral lesion is unusual and clinically unexpected, CFT should be considered in the differential diagnosis of rectal submucosal tumor.

Expression of the transducin-like enhancer of split 1 (TLE1) by immunohistochemistry (IHC) has been widely used as a biomarker for the diagnosis of synovial sarcoma. Although TLE1 expression can be identified in more than 90% of synovial sarcomas, positive staining has been reported in up to one third of nonsynovial sarcomas, including peripheral nerve sheath tumors and neoplasms of fibrous and adipose tissues. The low specificity of this test in soft tissue tumors raises concern on its clinical application as a diagnostic biomarker. As synovial sarcoma is frequent among the differential diagnosis of unclassified high-grade sarcomas, and considering that the specificity of TLE1 antibody in this tumor group remains unclear, we evaluated TLE1 expression by IHC in 42 unclassified high-grade sarcomas. SS18 (SYT) gene break-apart analyses by fluorescence in situ hybridization were simultaneously performed as a gold standard biomarker for synovial sarcoma. Five cases that were positive for the SS18 break-apart by fluorescence in situ hybridization were also positive for TLE1 by IHC, whereas the remaining 37 cases negative for SS18 break-apart were all negative for TLE1. The results showed no evidence of nonspecific TLE1 expression in the nonsynovial high-grade sarcomas. We concluded that TLE1 is a highly specific biomarker for synovial sarcoma in the setting of differential diagnosis of unclassified high-grade sarcomas.

The authors present an extremely rare case of a fibrotic nodule arising from the cerebellopontine (CP) angle. A 57-year-old male had suffered from hearing disturbance and tinnitus for several years. Computed tomography revealed a high-density mass in the left CP angle with little enhancement after intravenous administration of contrast media. Magnetic resonance imaging (MRI) showed a very hypointense mass on T2-weighted imaging. T1-weighted MRI with gadolinium revealed very faint, delayed enhancement of the tumor. The patient underwent surgical resection of the tumor. Histopathologically the lesion comprised entirely fibrotic tissue consisting of thick collagenous fibers and sclerosing blood vessels with a few intervening viable cells with, partly, the immunophenotype of arachnoid cells. Intracranial fibrotic nodules are extremely rare. This tumor, however, had some radiological features similar to those of other, more common, tumors for example meningiomas or solitary fibrous tumors; it was, therefore, difficult to distinguish it from the others. It is believed that intracranial fibrotic nodules usually have benign, non-neoplastic characteristics, although their natural history is not yet fully understood. It is, therefore, necessary to be able to perform a differential diagnosis that will distinguish this rare condition from other intracranial fibrous neoplasms that occasionally have malignant features.

Distinguishing malignant mesotheliomas from benign mesothelial proliferations on hematoxylin and eosin-stained sections can be extremely challenging. Various immunohistochemical stains have been suggested to help in making this distinction, but all are controversial. Recently, IMP3 (insulin-like growth factor II mRNA binding protein 3) and GLUT-1 (glucose transporter protein 1) have been proposed as immunohistochemical markers that are positive in mesotheliomas but not in benign proliferations. We evaluated the performance of these markers on a tissue microarray containing 30 malignant mesotheliomas and 48 benign thoracic or abdominal mesothelial proliferations. IMP3 was positive in 53% of malignant and 27% of benign cases (P=0.03), whereas GLUT-1 was positive in 60% of malignant and 13% of benign cases (P=0.0003). Forty-three percent of malignant cases, but only 4% of benign cases, were positive for both IMP3 and GLUT-1 (P=0.00003). We conclude that, statistically, both IMP3 and GLUT-1 are more frequently positive in malignant compared with benign mesothelial processes; however, the frequency of positive staining in benign cases is too high to allow their diagnostic use as single stains. The combination of both markers may be of greater diagnostic value, but this hypothesis should be confirmed in further studies.

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that arise most commonly in the pleura but have been increasingly reported in extrapleural sites. The authors report the case of an SFT of the scalp that manifested as an enlarging scalp mass in a 2-year-old boy. The mass was surgically excised. Histological examination showed it to be composed of fusiform cells of variable cellularity with a central hyalinization zone. Immunohistochemical staining was positive for CD34 and negative for smooth muscle actin, S100 protein, desmin, and h-caldesmon. On 1-year follow-up, there was no recurrence of the mass. This case presented some diagnostic difficulty because of the wide range of possible diagnoses for a pediatric scalp mass; however, the distinct immunohistochemical profile helped to eliminate other more frequent fibrous tumors of the scalp. The behavior of scalp SFTs is usually benign, but their course can be unpredictable, and recognition of these lesions is essential.

Purpose of Review: Solitary fibrous tumor of the pleura (SFTP) is a rare neoplasm of the pleura. Although an increasing number of case series have been reported in recent years, so far clinical behavior is still unpredictable. The following article presents a detailed review of the recent larger series of SFTP with particular attention to the clinical presentation, pathologic characteristics and surgical features in order to define more precisely the long-term outcome after treatment of this rare entity., Recent Findings: Usually, after a complete surgical resection a very long survival could be expected in almost all cases. However, the preoperative detection and management of malignant SFTPs are still challenging issues., Summary: SFTP remains an enigmatic tumor. Clinical and radiological assessment is often unsatisfactory to obtain a definitive diagnosis. Benign SFTPs are almost always cured with complete surgical resection, and in cases of recurrence the re-do resection of benign recurrences is usually curative. Long-term survivals are also possible for malignant SFTPs, although a higher recurrence rate and higher tumor-related mortality can be expected in these cases. Histologic characteristics distinguishing benign from malignant variants are crucial in estimating the risk of recurrence and planning adjuvant therapies.

Cutaneous clear cell neoplasms represent a heterogenous group of several primary and metastatic tumors with diverse histogenesis. Tumors with widespread clear cell change can seem strikingly similar under the microscope resulting in diagnostic difficulties. Although most cases are idiopathic, intracytoplasmic accumulation, artifact of tissue processing, and degenerative phenomenon have been cited as possible causes of clear cell change. An awareness of the various entities demonstrating this attribute, judicious use of ancillary techniques, and knowledge of the clinical setting are crucial to the accurate diagnosis. This review details the histological features of clear cell neoplasms of the skin with particular emphasis on the discriminating features.

We report the case of solitary fibrous tumor of the pleura, which appeared to change its location. A computed tomography (CT) scan done at a previous hospital showed a tumor in the posterior mediastinum, suggesting that it was neurogenic. However, on the initial preoperative CT scan, the tumor seemed to have moved anteriorly, but when contrast material was injected; the tumor appeared in its original position. Video-assisted thoracoscopic surgery (VATS) revealed a pedunculated and free-moving tumor, originating from the visceral pleura. We diagnosed this unusual migrating tumor as a pedunculated solitary fibrous tumor of the pleura.

Myositis ossificans circumscripta (MOC), with nonneoplastic heterotopic bone formation in soft tissue and skeletal muscle, is rare in children. Extraskeletal osteosarcoma is a very rare malignant mesenchymal neoplasm of soft tissues in children. At onset, it may be difficult to distinguish MOC from a musculoskeletal infection or neoplasm, particularly in the absence of trauma, and a biopsy is frequently required. However, differentiating MOC from malignant neoplasm is imperative. We describe the case of a 22-month-old girl who presented with a benign fibrous-myofibroblastic tumor mimicking MOC. However, extraskeletal osteosarcoma was also considered in the differential diagnosis due to the absence of attachment of the lesion to the skeleton. Pathologic findings after a previous needle biopsy and posterior marginal resection exclude both differential diagnoses. Close follow-up during 3 years postoperatively showed no signs of recurrence., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Microcystic adnexal carcinoma of the skin is a very rare malignant tumour arising from the sweat glands. As far as we know, the MRI features of this tumour have not been described in the literature before. In this report we present the MRI features and pathological description of a case of a microcystic adnexal carcinoma in the cheek that was incidentally imaged during brain MRI examination. A review of the relevant literature as well as a discussion of MRI of skin tumours is also presented.

Ossifying fibromyxoid tumours (OFTs) are uncommon soft tissue tumours. A 73-year-old male presented with a painless exophytic mass located in the left scapular area which was identified 1 year earlier. An incisional biopsy was performed and microscopic features were compatible with OFT. Radiologic evaluation revealed multiple pulmonary metastasis. Although many cases persue an indolent biologic behaviour, local recurrence and metastasis have been reported and long-term follow-up should be considered.

Calcifying fibrous tumour (CFT) is a recently recognised rare benign lesion characterised by dense hyalinised collagenous tissue, psammomatous or dystrophic calcifications and a lymphoplasmacytic infiltrate. The usual locations of the lesion are the soft tissues of the extremities, but rarely it occurs in the abdomen. Recently, we experienced a case of CFT found in the liver of a 29-year-old woman. Here, we describe the characteristic radiological and histopathological findings, along with a review of the relevant literature.