Sclerosing Epithelioid Fibrosarcoma Research Articles

Novel KMT2B gene mutation in MUC4 positive low-grade fibromyxoid sarcoma

BackgroundLow-grade Fibromyxoid Sarcoma(LGFM)is a rare fibrosarcoma, which mainly occurs in young people and is mostly seen in the trunk and limbs. The tumor is usually FUS-CREB3L2 fusion caused by t(7;16)(q32-34;p11)chromosome translocation, and rarely FUS-CREB3L1 and EWSR1-CREB3L1 fusion. MUC4 diffuse strong positive can be used as a specific index of LGFM. LGFM is similar to Sclerosing Epithelioid Fibrosarcoma(SEF) and may have the same origin.Case presentationWe report a case of LGFM in the chest wall. A female who is 59 years old. In 2016, CT showed dense nodule shadow and focal thickening of the left pleura, the patient underwent surgery, Pathological report that low to moderate malignant fibrosarcoma(fibromyxoid type). The CT re-examination in 2021 showed that the tumors on the left chest wall were significantly larger than before. Pathological examination showed the disease is composed of alternating collagen like and mucinous areas. Under high-power microscope, the tumor cells are consistent in shape, spindle or short spindle, and the tumor cells are arranged in bundles. In local areas, the density of tumor cells is significantly increased, mixed with collagen fibers, and small focal SEF appear. The result of immunohistochemistry showed that SMA, Desmin, CD34, STAT6, S100, SOX10, HMB45 and Melan A were negative, EMA was weakly positive, MUC4 was diffuse and strongly positive, and Ki67 index was low (3%).ConclusionSequencing results showed that MET, EGFR, KMT2B and RET gene were mutated in LGFM, and KMT2B gene had cancer promoting effect, but there was no literature report in LGFM, which may be of certain significance for the diagnosis and treatment of LGFM.

The Regulatory Network of CREB3L1 and Its Roles in Physiological and Pathological Conditions.

CREB3 subfamily belongs to the bZIP transcription factor family and comprises five members. Normally they are located on the endoplasmic reticulum (ER) membranes and proteolytically activated through RIP (regulated intramembrane proteolysis) on Golgi apparatus to liberate the N-terminus to serve as transcription factors. CREB3L1 acting as one of them transcriptionally regulates the expressions of target genes and exhibits distinct functions from the other members of CREB3 family in eukaryotes. Physiologically, CREB3L1 involves in the regulation of bone morphogenesis, neurogenesis, neuroendocrine, secretory cell differentiation, and angiogenesis. Pathologically, CREB3L1 implicates in the modulation of osteogenesis imperfecta, low grade fibro myxoid sarcoma (LGFMS), sclerosing epithelioid fibrosarcoma (SEF), glioma, breast cancer, thyroid cancer, and tissue fibrosis. This review summarizes the upstream and downstream regulatory network of CREB3L1 and thoroughly presents our current understanding of CREB3L1 research progress in both physiological and pathological conditions with special focus on the novel findings of CREB3L1 in cancers.

The Expression of Mucin-4 (MUC4) in Sarcomas Apart From Sclerosing Epithelioid Fibrosarcoma and Low-Grade Fibromyxoid Sarcoma.

Background Low-grade fibromyxoid sarcoma (LGFMS) and sclerosing epithelioid fibrosarcoma (SEF) are two rare but aggressive soft tissue sarcomas that can be difficult to distinguish due to histopathological similarities. The present study examines the diagnostic capacities of mucin-4 (MUC4), a transmembrane mucin, in identifying different types of sarcomas and broadens its evaluation to include a wide range of sarcomas. Methods Immunohistochemical (IHC) examination of tissue samples from various sarcomas was performed using a mouse anti-MUC4 monoclonal antibody. IHC was conducted on 4-mm thick formalin-fixed paraffin-embedded tissue sections after pressure cooker antigen retrieval with a mouse anti-MUC4 monoclonal antibody. Results MUC4 was shown to be highly expressed in SEF (n=13) and LGFMS (n=10), while focal positivity in synovial sarcoma (n=1). Other sarcomas, such as malignant peripheral nerve sheath tumors, fibrosarcoma, leiomyosarcoma, liposarcoma, and myxofibrosarcoma, exhibited no expression (n=0). These findings are consistent with previous research and support MUC4 specificity as a SEF and LGFMS marker.This study provides information on the diagnostic efficacy of MUC4, particularly in the context of certain subtypes. It not only helps our understanding of these unique instances, but it also provides context for histopathological and IHC findings in soft tissue sarcoma. Furthermore, this study investigates the influence of age and gender on MUC4 expression in a range of sarcomas, which was typically understudied in the literature and found no relation with expression of MUC4. Conclusion In conclusion, this study adds to our understanding of soft tissue sarcomas by emphasizing the crucial role of MUC4 in certain sarcoma subtypes while acknowledging the complex variety of the sarcoma landscape. Further research is needed to understand the molecular mechanism that governs marker expression patterns, as well as the therapeutic implications.

Sclerosing Epithelioid Fibrosarcoma (SEF) versus Low Grade Fibromyxoid Sarcoma (LGFMS): Presentation and outcome in the nationwide NETSARC+ series of 330 patients over 13 years

Sclerosing Epithelioid Fibrosarcoma (SEF) and Low Grade Fibromyxoid Sarcoma (LGFMS) are ultrarare sarcomas sharing common translocations whose natural history are not well known. We report on the nationwide exhaustive series of 330 patients with SEF or LGFMS in NETSARC+ since 2010. Patients and methodsNETSARC (netsarc.org) is a network of 26 reference sarcoma centers with specialized multidisciplinary tumor boards (MDTB). Since 2010, (i) pathological review has been mandatory for sarcoma,and (ii) tumour/patients’ characteristics have been collected in the NETSARC+ nationwide database. The characteristics of patients with SEF and LGFMS and their outcome are compared. Results35/73 (48%) and 125/257(49%) of patients with SEF and LGFMS were female. More visceral, bone and trunk primary sites were observed in SEF (p < 0.001). 30% of SEF vs 4% of LGFMS patients had metastasis at diagnosis (p < 0.0001). Median size of the primary tumor was 51 mm (range 10–90) for LGFMS vs 80 (20−320) for SEF (p < 0.001). Median age for LGFMS patients was 12 years younger than that of SEF patients (43 [range 4–98] vs 55 [range 10–91], p < 0.001). Neoadjuvant treatment was more often given to SEF (16% vs 9%, p = 0.05). More patients with LGFMS were operated first in reference centers (51% vs 26%, p < 0.001). The R0 rate on the operative specimen was 41% in LGFMS vs 16% in SEF (p < 0.001). Median event-free survival (EFS) of patients with SEF and LGFMS were 32 vs 136 months (p < 0.0001). The median overall survival (OS) was not reached. Fifty-months OS was 93% vs 81% for LGFMS vs SEF (p = 0.05). Median OS was 77 months after first relapse, similar for SEF and LGFMS.In multivariate analysis, age, tumor size, metastasis at diagnosis were independent prognostic factors for OS in LGFMS. ConclusionsAlthough sharing close molecular alterations, SEF and LGFMS have a different natural history, clinical presentation and outcome, with a higher risk of metastatic relapse in SEF. Survival after relapse is longer than with other sarcomas, and similar for SEF and LGFMS.

Sclerosing epithelioid fibrosarcoma – a rare variant with myriads of differentials

Sclerosing Epithelioid Fibrosarcoma is a rare form of soft tissue sarcoma, with increased propensity for local recurrence and metastases mainly pulmonary and pleural in about 50% of cases. It carries morphological resemblance with many sarcomas, hence detailed and comprehensive immunohistochemical examination is mandatory for definitive diagnosis. Hereby, we present a case in a 39 year old male, who presented with a painless right thigh swelling. The histopathological examination revealed nests of epithelioid cells embedded in a densely sclerotic matrix, and immunohistochemistry showed MUC4 and Vimentin positivity, rendering the final diagnosis of Sclerosing Epithelioid Fibrosarcoma.

1928P Differential presentation and outcome of sclerosing epithelioid fibrosarcoma (SEF) vs low grade fibromyxoid sarcoma (LGFMS): The nationwide series of 330 patients in NETSARC since 2010

1928P Differential presentation and outcome of sclerosing epithelioid fibrosarcoma (SEF) vs low grade fibromyxoid sarcoma (LGFMS): The nationwide series of 330 patients in NETSARC since 2010

Sclerosing epithelioid fibrosarcoma of bone with hybrid features: clinicopathologic, radiologic, and molecular analysis of three cases.

Sclerosing epithelioid fibrosarcoma (SEF) occurring as a primary bone tumor is exceptionally uncommon. Even more rare are cases of SEF that show morphologic overlap with low-grade fibromyxoid sarcoma (LGFMS). Such hybrid lesions arising within the bone have only rarely been reported in the literature. Due to their variegated histomorphology and non-specific radiologic features, these tumors maypose diagnostic difficulties. Herein we describe three molecularly confirmed primary bone cases of sclerosing epithelioid fibrosarcoma that demonstrated prominent areas showing the features of LGFMS and with areas resembling so-called hyalinizing spindle cell tumor with giant rosettes (HSCTGR). Two patients were female and one was male aged 26, 47, and 16, respectively. The tumors occurred in the femoral head, clavicle, and temporal bone. Imaging studies demonstrated relatively well-circumscribed radiolucent bone lesions with enhancement on MRI. Cortical breakthrough and soft tissue extension were present in one case. Histologically the tumors all demonstrated hyalinized areas with SEF-like morphology as well as spindled and myxoid areas with LGFMS-like morphology. Two cases demonstrated focal areas with rosette-like architecture as seen in HSCTGR. The tumors were all positive for MUC4 by immunohistochemistry and cytogenetics, fluorescence in-situ hybridization, and next-generation sequencing studies identified EWSR1 gene rearrangements confirming the diagnosis in all three cases.Hybrid SEF is exceedingly rare as a primary bone tumor and can be difficult to distinguish from other low-grade spindled and epithelioid lesions of bone. MUC4 positivity and identification of underlying EWSR1 gene rearrangements help support this diagnosis and exclude other tumor types.

Needle tract seeding of a sclerosing epithelioid fibrosarcoma in a biopsy tract: a case report

BackgroundA sclerosing epithelioid fibrosarcoma (SEF) is an uncommon tumor of the deep soft tissue. An SEF has been described as a low-grade tumor with high local recurrence and metastatic rates. Generally, in bone and soft tissue tumors, a resection of the biopsy route is recommended; however, there is limited evidence with respect to the dissemination of the tumor tissue during a needle biopsy.Case presentationA mass in the right pelvic cavity, with no symptoms, was observed in a 45-year-old woman during a gynecological examination. Computed tomography (CT) revealed a multilocular mass with calcification in the pelvic cavity. The magnetic resonance imaging (MRI) showed an iso-signal intensity on T1 weighted images and hypo- and iso-signal intensity on T2 weighted images. The CT-guided core needle biopsy was performed using a dorsal approach, and the biopsy diagnosis was a low-grade spindle cell tumor. The tumor was excised using an anterior approach. The tumor tissue comprised spindle cells and epithelioid cells with irregular nuclei, and the immunohistological analysis was positive for vimentin and epithelial membrane antigen, which was consistent with a diagnosis of sclerosing epithelioid fibrosarcoma. Five years after the surgery, the MRI showed a tumor recurrence in the subcutaneous tissue of the right buttock, which was consistent with the needle biopsy tract. The patient underwent a tumor excision, and the resected tumor was similar to the primary tumor.ConclusionsThe recurrent tumor was excised with a surgical margin, and the tumor specimen had the histological features of a sclerosing epithelioid fibrosarcoma. It was difficult to investigate the association of the core needle biopsy with the tumor recurrence because the approach of the biopsy tract is usually same as that used in a tumor excision. However, the present case indicated the tumor may recur in the biopsy tract of a soft tissue sarcoma. Surgeons should be aware of the possibility of disseminating tumor tissues in a needle biopsy.

Sclerosing epithelioid fibrosarcoma of the foot: A case report

Sclerosing epithelioid fibrosarcoma (SEF) is a rare and distinctive variant of fibrosarcoma. To date, about 100 cases only have been documented. Histopathologically, it resembles a variety of benign, pseudosarcomatous and other malignancies. Early diagnosis and treatment are vital for improving the treatment outcomes.

The clinicopathological spectrum of sclerosing epithelioid fibrosarcoma: report of an additional series with review of the literature

We present a case series of sclerosing epithelioid fibrosarcoma (SEF) to further characterise its clinical and pathological features. Twenty-one patients with SEF were included in this study. There were 12 males and nine females (range 25-63 years; median 38 years). Tumours were located in the kidney (n=5), thigh (n=3), chest wall (n=3), head and neck (n=2), bone (n=2), abdominal wall (n=1), psoas major (n=1), retroperitoneum (n=1), omentum (n=1), popliteal space (n=1) and lung (n=1). Tumour sizes ranged from 2.5 to 16 cm (median 7 cm). Microscopically, epithelioid tumour cells were arranged in nests and cords and embedded in a dense sclerotic stroma. Some tumours showed myxoid areas, fibroma-like areas, acinar growth patterns and haemangiopericytoma-like appearance. A few tumour cells presented a rhabdomyoid shape. Calcification, ossification, cystic and necrosis were observed in some cases. The diagnosis was confirmed by immunoreactivity for MUC4, and by further fluorescence in situ hybridisation (FISH) or next generation sequencing (NGS) analysis. Clinical follow-up was available for 16 cases (median, 24 months; range 6-62 months). Seven patients developed metastases to lung (n=3), bone (n=3), brain (n=2) and back (n=1). Four patients developed a local recurrence. Three patients died of disease. Overall survival (OS) of SEF was related to patient age (p=0.001) and progression-free survival (PFS) was related to tumour size (p=0.046). In addition to soft tissue, SEF is more likely to involve the viscera and the abdominal cavity and has morphological variants. Familiarity with its distinctive clinical and pathological features helps avoid misdiagnosis.

PSUN380 A Case of Sclerosing Epithelioid Fibrosarcoma With Metastases to the Thyroid

Abstract Background Sclerosing Epithelioid Fibrosarcoma (SEF) is a rare form of soft tissue sarcoma, often presenting in the soft tissues of the extremities. This tumor is characterized by slow growth, often with local recurrences and/or distant metastases. First described in 1995, subsequent case reports and case series have demonstrated that metastases are primarily to the lung, pleura and bone, but can occur anywhere. Treatment is primarily by wide excision and adjuvant chemotherapy or radiotherapy. However, treatment of this rare form of sarcoma is often unsatisfactory. Clinical case A 36-year-old female, had for 30 years presented with a slowly enlarging mass on the left axilla. She had no constitutional symptoms and had previously been in good health. She was first diagnosed with SEF when she presented with abdominal pain where workup showed elevated Lipase 8,098 U/L (73-393 U/L) and Amylase 976 U/L (25-115 U/L). CT scans showed an ill-defined hypodense focus in the body of the pancreas, with incidental findings of a mixed intensity ovoid lesion in the left erector spinae, and heterogeneously enhancing ovoid masses in the left axilla, left lateral chest wall, left lower lung lobe, and the liver. Biopsy of the left axillary mass showed a round cell sarcoma consistent with Sclerosing Epithelioid Fibrosarcoma. PET scan confirmed widespread metastases to the lungs, pancreas, abdominal wall, left thigh and scalp. She underwent wide excision of the masses in the left axilla, thigh, and scalp. Adjuvant chemotherapy with Doxorubicin and Ifosfamide was then initiated. 6 months after starting treatment, she reported a rapidly enlarging anterior neck mass. She denied tremors, palpitations, any change in weight, heat/cold intolerance, changes in bowel movement, fatigue or muscle weakness. On physical examination there was a 2×2 cm, firm, non-tender, palpable nodule on the right thyroid lobe. Thyroid function tests were as follows: TSH 0.52 uIU/mL (0.55-4.78 uIU/mL), FT4 1.27 ng/dL (0.89-1.76 ng/dL), FT3 2.84 pg/mL (2.30–4.20 pg/mL). On thyroid ultrasound there was a 2.6×1.8×2.4 cm, mixed hypoechoic, solid, lobulated nodule in the upper to middle third of the right thyroid lobe, and a 0.3×0.2×0.3 cm hypoechoic solid nodule in the lower third of the left thyroid lobe. FNAB showed hypercellular smears with atypical round to spindle-shaped cells arranged in singly and loose to crowded clusters. She underwent total thyroidectomy, and histopathologic examination was consistent with a multifocal metastatic Sclerosing Epithelioid Fibrosarcoma. She was subsequently started on Levothyroxine replacement. Conclusion This case, to our knowledge, is the first reported case of Sclerosing Epithelioid Fibrosarcoma (SEF) metastatic to the thyroid. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Metastatic sclerosing epithelioid fibrosarcoma in an adult male from a tertiary care centre in India: a case report

Sclerosing epithelioid fibrosarcoma (SEF) is an extremely rare subtype of soft tissue sarcoma and the data from India is sparse. It is an unusual variant of fibrosarcoma that commonly arises in the soft tissues of the limb, head and neck, trunk and occasionally in the visceral organs and bones. This entity is commonly reported in the middle age group, men and women alike. Pathological clinchers include MUC 4 (Mucin 4, cell surface associated) positivity by immunohistochemistry, FUS-CREB3L1 fusion and EWSR1 rearrangement. This disease is notoriously known for its local recurrence and metastatic spread. Response to systemic therapy is poor and relapses are frequent. The role of targeted and immunotherapy is not well defined. Here we report a 46-year-old gentleman who presented to the Sarcoma Medical Oncology Clinic in our centre. He had primary involvement of right pubic bone with metastasis to liver, lung and diffuse lytic bony lesions. His diagnosis was reviewed multiple times before coming to final diagnosis of SEF. His molecular test for EWSR1 rearrangement was positive by fluorescence in-situ hybridisation. He did not respond to palliative doxorubicin, pazopanib and gemcitabine and docetaxel. Through this case report, we would like to highlight the rarity of this sarcoma, its classical pathological features, its close relationship to low-grade fibromyxoid sarcoma and the limited therapeutic options available. Hence, there is a need for further research in this entity.

Pseudoangiosarcomatous squamous cell carcinoma: a rare subtype of squamous cell carcinoma that needs to be differentiated from angiosarcoma and has a poor prognosis.

This study aimed to investigate the formation mechanism of Pseudoangiosarcoma squamous cell carcinoma (PASCC). The researchers reviewed ten cases of PASCC and summarize their clinical outcomes, pathological morphological traits, immunophenotypes, treatment plans and the corresponding follow-up data. Results showed that the pathological morphology revealed complex reticular structures, where numerous tracts of anastomose, and lacunar structures lined with atypical neoplastic cells, which resembles the histopathological appearance of angiosarcoma. Particularly, we observed pathologic patterns that resemble Sclerosing Epithelioid Fibrosarcoma (or Myxoid Fibrosarcoma) in the patients who suffered a relapse. All cases present negative results for vascular markers (CD31, ERG) and positive results for epithelial markers (CK-pan, p40). The average age of the participants is 60 years old (range: 48-79), relative aged, and there is no significant difference between male and female participants (6 men and 4 women). The locations of neoplasms involve face (n=3), upper limbs (n=1), waist(n=1), cervix uteri (n=1), lungs (n=2), thyroid (n=1), and breasts (n=1). All participants had received clinical follow-ups that range from 4 to 47 months, during which the researchers observed Lymph Node Metastases developed in three participants (out of 10; 30%); Distant Metastases in five participants (out of 10; 50%); two local recurrences at the site of surgical resection; and four deaths due to disease (out of 10; 40%), with 9.5 months estimated median survival time and 9 months mean survival time. It was concluded that PASCC presents the tendency for recurrence and metastasis. Accurate pathological diagnosis and standardized medical procedures are crucial to the treatment of PASCC. Epithelial-Mesenchymal Transformation (EMT) and P53 gene mutation are involved in the formation of PASCC.

Primary Sclerosing Epithelioid Fibrosarcoma of the Kidney: A Case Report and Review of the Literature

Primary Sclerosing Epithelioid Fibrosarcoma of the Kidney: A Case Report and Review of the Literature

A group of sclerosing epithelioid fibrosarcomas with low-level amplified EWSR1-CREB3L1 fusion gene in children

Sclerosing epithelioid fibrosarcoma (SEF), typically arising in middle-aged and older adults, is a rare malignant fibroblastic neoplasm characterized by epithelioid fibroblasts embedded in sclerotic hyalinized stroma. This tumor frequently harbors translocation between EWSR1 and CREB3 subfamily members. Here, we describe four cases of SEF with unique genetic characteristics in children. All tumors were located in the deep soft tissue of the trunk and celom. Histopathologically, the tumors were featured by prominent hyalinized sclerotic collagenous stroma within which relatively bland and monomorphic epithelioid cells were arranged in cords, nests, or sheets. Low-grade fibromyxoid sarcoma-like zones varied among cases. MUC4 was strong and diffuse. CD99 was positive. Transmission electron microscopy demonstrated spindle or polyhedral neoplastic cells with a collagen fiber-rich stroma. Interphase fluorescence in situ hybridization (FISH) revealed local amplification of the EWSR1 locus. Whole-genome sequencing indicated translocation between EWSR1 and CREB3L1 together with low-level amplification of the fusion parts. RT-PCR and Sanger sequencing confirmed the fusion transcript. Single nucleotide polymorphism and FISH analyses demonstrated co-deletion of 11p and 22q. The consistent genetic features indicated the presence of a unique molecular variant of SEF. Data Availability StatementThe data used to support the findings of this study are available from the corresponding author upon request.

Sclerosing Epithelioid Fibrosarcoma; A Case report and review of literature

Abstract Introduction/Objective Sclerosing Epithelioid Fibrosarcoma (SEF) is an unusual, rare clinically aggressive form of soft tissue sarcoma. It is characterized by a slow evolution, with local recurrences and late metastases that are mainly pulmonary and pleural in about 80% of cases. SEF has distinctive morphology and occurs most commonly in deep soft tissue of adult extremities. Lesions involving the head and neck region are uncommon and rare intraosseously in oral cavity. Methods/Case Report Herein we report a case of a 52-year-old male who presented with a symptomatic radiolucent lesion at apex #18, with clinical impression of periapical granuloma. The patient did present with pain associated with lower left quadrant #18 area, for several days to pressure and hot temperature. A periapical radiograph revealed a large ill-defined radiolucent area at apex of resorbing roots #18. The patient’s medical history was significant with history of cancer diagnosis of sclerosing epithelioid fibrosarcoma of skull treated by chemotherapy and radiation. Microscopic examination of the specimen revealed a multi-fragmented specimen consisting of numerous fragments and islands of highly cellular, basophilic bone and osteoid surrounded by loose fibrous stroma which contains large lobules and islands of round to oval cells, with distinct cell borders and faintly granular eosinophilic cytoplasm. Separate islands of tumor cells surround large islands of necrosis with the background stroma appearing as hyalinized and eosinophilic with the basaloid cells demonstrating smudge and crush artifact. Peripherally, spindled cells are noted and faint areas of eosinophilic osteoid within the eosinophilic background stroma. Lesional cells are MUC4 strong, diffusely positive and strongly positive for INI-1. CD43, CD20, PAX-5, CD3, Desmin, CD34, S100, CD99, AE1/3 and SMA are interpreted to be negative. A diagnosis of metastatic sclerosing epithelioid fibrosarcoma was made, with correlation with the primary lesion was recommended. Results (if a Case Study enter NA) N/A Conclusion The clinical and histological findings of our case correlate with the diagnostic criteria of sclerosing epithelioid fibrosarcoma. Despite its microscopic features can create diagnostic difficulties, in that SEF can resemble a variety of benign and pseudosarcomatous as well as malignant lesions, our case diagnosis was confirmed by morphology and MUC4 diffuse strong reactivity and negativity for other markers.

Sclerosing epithelioid fibrosarcoma: in-depth review of a genetically heterogeneous tumor.

First described in 1995 by Meis-Kindbloom et al. as a variant of fibrosarcoma simulating carcinoma, sclerosing epithelioid fibrosarcoma (SEF) is a malignant soft tissue sarcoma characterized by epithelioid cells in dense sclerotic stroma, frequent immunoreactivity for MUC4 and heterogeneous genetic profile with recurrent EWSR1 gene rearrangement. It typically affects middle-age adults with a predilection for the lower extremity. It is believed that SEF is closely related to low-grade fibromyxoid sarcoma (LGFMS), both tumors show overlapping features in morphology, immunophenotype, and molecular profile. In this review, we discuss the clinical, morphologic, and immunohistochemical features of SEF with particular emphasis on its molecular diversity and relation to LGFMS.

Sclerosing epithelioid fibrosarcoma of bone: morphological, immunophenotypical, and molecular findings of 9 cases.

Primary sclerosing epithelioid fibrosarcoma (SEF) of bone is a rare and scarcely reported neoplasm. We document clinicopathological and molecular features of 9 additional cases. Five males and 4 females had a mean age of 39 years (14-71 years). Most tumors affected flat/irregular bones; only 3 cases involved a long bone. By radiology, it has characteristic radiographic features of a predominantly lytic expansile lesion with a sclerotic rim. Referring diagnoses were SEF (n = 2), low-grade osteosarcoma (n = 2), chondrosarcoma (n = 1), and chondromyxoid fibroma (n = 1). Histologically, five cases revealed classical morphology of SEF of soft tissue. Remaining cases were classified as hybrid SEF/low-grade fibromyxoid sarcoma, characterized by spindle or stellate cells, prominent stroma, and giant hyalinized areas. Various morphological deviations such as prominent vasculature (n = 3), osteoid-like material (n = 4), or parallel bone trabeculae (n = 2) were observed. Immunohistochemically, all cases showed diffuse and strong MUC4 expression. SATB2 was observed in 5/8 cases. Using FISH, EWSR1, and FUS rearrangements were detected in 4 cases and 1 case, respectively. EWSR1-CREB3L1 fusion was identified in 1 additional case by next-generation sequencing. Recurrence and metastasis were observed in 1 case and 2 cases, respectively. All but one patient were alive with disease for a mean interval of 31 months. SEF of bone is a relatively indolent sarcoma of adults, most commonly located in the flat/irregular bones. Due to overlapping histological features, it is often misdiagnosed as osteosarcoma or a chondroid tumor. Most SEF of bone exhibit EWSR1 rearrangements, but rare cases may harbor a FUS gene fusion.

Sclerosing epithelioid fibrosarcoma: cytologic characterization with histologic, immunohistologic, molecular, and clinical correlation of 8 cases

Sclerosing epithelioid fibrosarcoma (SEF) is an uncommon malignant fibroblastic neoplasm. The diagnosis is typically made on core needle biopsy or resection specimens. Cytomorphologic characterization of SEF has been limited to rare case reports in the literature. The goal of this study was to review a series of cases of SEF and to determine the feasibility of cytologic diagnosis of this rare tumor. Eight SEF cases from 2009 to 2019 were identified in a retrospective review of 3 participating institutions. Cytomorphologic and corresponding histologic, immunophenotypic, molecular, and clinical data were examined and described. Patients were of median age 41 years old at diagnosis with a median follow-up of 35.5 months. These tumors, with a median greatest dimension of 13.4 cm, were located in the lower extremities, abdomen, retroperitoneum, head, groin, sacrum, and lung. The tumor cells ranged from small round, medium-sized ovoid/short spindle, to epithelioid/plasmacytoid cells. A sclerotic, fibrous to myxoid stroma was seen. Most samples revealed low-grade cytology. Two cases showed tumor necrosis. Only 3 cases with cell block/positive MUC4 immunostain were diagnostic. Corresponding molecular testing for EWSR1 gene rearrangement and/or EWSR1-CREB3L1 fusion were positive in 5 of 8 cases on biopsy or surgical samples. An additional case was positive for FUS-CREB3L2 fusion. Diagnosis of SEF based solely upon cytologic features remains challenging. Epithelioid or plasmacytoid morphology mimics common malignancies. A supportive clinical history, MUC4 immunohistochemistry, and characteristic molecular result should be used to aid the diagnosis.

Rib destruction by epithelioid tumour in a young man

A man in his 30s presented with back pain and was found to have a tumour in the posterior chest wall. Imaging showed an expansile mass measuring up to 6.7...