Sclerosing epithelioid fibrosarcoma: cytogenetic analysis of FUS rearrangement

Sclerosing epithelioid fibrosarcoma (SEF) is a rare but distinct variant of fibrosarcoma. A 43-year-old man presented with a lesion in his back that had been present for three years but had recently increased in size. Magnetic resonance imaging (MRI) revealed a 6-cm sized ovoid mass showing low intensities on T1 and T2 weighted images. Histologically, the tumor was of moderate cellularity, and the cells were relatively uniform in size and shape. The cells were epithelioid, round, oval and polygonal with clear and slightly eosinophilic cytoplasm, forming nests, cords, or sheet-like patterns with a dense collagenous and hyalinized matrix. The tumor was positive for vimentin, but negative for smooth muscle actin, desmin, HMB45, and CD34. Although the tumor showed nuclear overexpression of beta-catenin protein, the CTNNB1 exon3 mutation was not detected. Fluorescent in situ hybridization for FUS using dual color break-apart probes showed rearrangement of the FUS. In accordance with previous studies, our case showed positive findings of FUS rearrangement, reinforcing the notion of a close relationship between low grade fibromyxoid sarcoma and SEF.     

硬化性上皮样纤维肉瘤临床病理特点及其诊断

目的探讨硬化性上皮样纤维肉瘤(sclerosing epithelioid fibrosarcoma,SEF)的临床病理学特征、诊断及鉴别诊断。方法对1例SEF进行组织学观察和免疫组化标记,同时复习相关文献。结果SEF主要以上皮样细胞伴大量胶原纤维为特征,瘤细胞胞质透亮,似上皮细胞,排列呈条索状,间质中大量胶原纤维发生透明变性,形成硬化性基质。肿瘤细胞vimentin阳性,cytokeratin和actin阴性。结论SEF是一种较为罕见的软组织肿瘤,应注意与一些具有上皮样形态和硬化性间质的肿瘤相鉴别。     

Sclerosing Epithelioid Fibrosarcoma of the Pituitary

Primary pituitary sarcoma in the absence of previous radiation therapy is very rare, only eight cases having been reported. We present the first reported case of sclerosing epithelioid fibrosarcoma of the pituitary, a 56-year-old woman presenting with diplopia and panhypopituitarism. Magnetic resonance imaging showed a 1.2 × 0.4 × 0.5-cm sellar mass invading the right cavernous sinus. Despite surgery and radiation therapy, our patient developed intracranial metastases and died 2 years after the initial diagnosis. Sclerosing epithelioid fibrosarcoma is an infrequently occurring, distinct variant of soft tissue fibrosarcoma. Its immunophenotype includes vimentin and occasionally CD-34, B cell lymphoma-2, S-100 protein, or keratin expression. Although initially thought to be a low-grade lesion, sclerosing epithelioid fibrosarcomas may also behave in a high-grade manner.     

Sclerosing variant of epithelioid angiomyolipoma

Presented herein are two unusual epithelioid angiomyolipomas (AML) displaying prominent stromal sclerosis. Both patients were middle-aged women without a clinical history of tuberous sclerosis. One patient (case 1) had a 2 cm lesion arising in the renal cortex, and another (case 2) had a pararenal retroperitoneal tumor measuring 13 cm. Both tumors were composed of sheets or nests of polygonal epithelioid or short spindle cells having uniform round to oval nuclei and eosinophilic cytoplasm with cords of hyalinized sclerotic stroma between them. The tumor in case 2 had small areas of mature-looking fat cells. Immunohistochemically, epithelioid tumor cells were diffusely positive for actins and desmin in both cases, and melanoma antigen recognized by T cells (MART)-1 was positive in patient 2. Scattered HMB-45-immunoreactive cells were identified in the sclerotic cords of both tumors, but epithelioid tumor cells were essentially negative for HMB-45. The characteristic clinicopathological and immunohistochemical features of the present cases are analogous to a subset of epithelioid AML or sclerosing perivascular epithelioid cell tumors previously reported.     

Overexpression of MDM2 in a sclerosing epithelioid fibrosarcoma: genetic, immunohistochemical and ultrastructural study of a case

Sclerosing epithelioid fibrosarcoma (SEF) is an extremely rare soft-tissue neoplasm. Here, we describe the molecular genetic alterations and histological, immunohistochemical and ultrastructural features of a primary SEF arising in the retroperitoneum. The tumor consisted of uniform small round to ovoid epithelioid cells, arranged in nests and cords and surrounded by a prominent hyalinized collagenous matrix. The tumor cells expressed only vimentin. Ultrastructurally, the tumor cells showed features of fibroblasts, with an abundant rough endoplasmic reticulum in the cytoplasm. Neither p53 gene mutations nor p53 protein overexpression were detected, but more than 70% of all tumor cells showed strong immunoreactivity with murine double minute 2 (MDM2). Our results suggest that MDM2 overexpression is likely to play a role in tumorigenesis in this lesion in p53-dependent or p53-independent pathways. To our knowledge, the present study is the first molecular genetic study of this rare lesion. Further studies will be necessary to clarify the molecular basis of tumorigenesis of this rare lesion.     

硬化性上皮样纤维肉瘤临床病理分析

目的 探讨硬化性上皮样纤维肉瘤（sclerosing epithelioid fibrosarcoma,SEF）的临床病理学特点、免疫表型和鉴别诊断。方法 对3例SEF进行细胞病理学、组织病理学及免疫表型观察。结果患者年龄60～64岁,其中女性2例,男性1例。临床表现为病程不等（2～15年）的软组织深部肿物,1例肿物明显增大,1例有疼痛。肿瘤分别位于大腿、前臂及臀部,累及骨骼肌,最大直径分别为3、9、10cm。肿瘤境界清楚,分叶状或多结节状,切面灰白色,质地坚硬。1例伴有钙化。细胞学印片显示肿瘤细胞散在,主要由小至中等大的上皮样细胞组成,圆形或卵圆形,有不等量的嗜酸性胞质,单个核,染色质稍深染,核仁不清,未见核分裂象及瘤巨细胞。冷冻切片检查：肿瘤细胞主要由小至中等大的上皮样细胞组成,多呈单个、单行或索状排列,夹杂分布于大量嗜伊红色、玻璃样变的胶原纤维中,类似于分化差的转移癌。石蜡切片显示在硬化的胶原性间质背景中上皮样肿瘤细胞呈单个、巢状、索状或腺泡状排列,形态相对均匀,细胞质稀少、透明或嗜酸,细胞核大小一致,椭圆形、圆形和多角形,染色质呈泡状或细点状,可见小嗜碱性核仁,异型性不明显,核分裂活性低（1～2／10HPF）。1例伴有局灶凝固性坏死。3例肿瘤的局部区域均有典型的纤维肉瘤形态。免疫表型：3例肿瘤均弥漫性表达vimentin,部分不同程度表达bcl-2（1／3）、p53（1／3）、EMA（1／3）、S-100蛋白（1／3）、CD34（2／3）。所有肿瘤均不表达细胞角蛋白、HMB-45、CIM5、CD68、desmin和CD99等。增值指数MIB．1为0～5％。3例术后随访6～30个月,无复发和转移。结论硬化性上皮样纤维肉瘤是一种罕见的特殊类型的纤维肉瘤,诊断需与一些具有上皮样细胞形态和硬化性间质的良恶性肿瘤鉴别。     

Sclerosing epithelioid fibrosarcoma

Sclerosing epithelioid fibrosarcoma (SEF) was first described in 1995 and since then 39 cases have been reported. Here we describe 6 cases of SEF (3 in women and 3 in men). The patients aged from 22 to 79 years. The tumours were located in soft tissues of the extremities (in 3 cases in the lower, in 2 instances in the upper extremity) and of the trunk (in 1 case). The lesions were partially nodular, of gray-white colour, and hard in consistency. Histologically, they were composed of epithelioid round to ovoid small cells with a sparse cytoplasm and a very low mitotic activity. The tumour cells formed cords and alveoli or were scattered individually within a dense hyalinized collagenous stroma. The neoplasms also contained foci of conventional fibrosarcoma, necrosis, calcification, and metaplastic bone. On immunohistochemistry, the neoplastic cells were positive for vimentin. Two cases were immunoreactive for epithelial membrane antigen and one tumour also for cytokeratins. The proliferative activity, assessed by MIB 1 antibody (Ki-67), was detected in 1-6% of neoplastic cells in primary tumours. Follow-up information was available in 5 patients. In two cases, there were local recurrences and distant metastases (in the lungs, upper extremity, and mediastinum). One of these patients died of SEF. The differential diagnosis of this relatively low-grade fibrosarcoma is broad and includes, along with a variety of benign and malignant soft tissue lesions, infiltrating carcinoma, and, to a lesser extent, sclerosing lymphoma.     

Sclerosing variant of perivascular epithelioid cell tumor in the female genital organs

Perivascular epithelioid cell tumor (PEComas), other than angiomyolipoma, clear cell 'sugar' tumor of the lung, and lymphangioleiomyomatosis, is an uncommon mesenchymal neoplasm that arises in the soft tissue and visceral organs. We report herein two cases of sclerosing PEComa; a distinctive variant of PEComa, which is characterized by extensive stromal hyalinization, occurring in the uterus and broad ligament. The patients were 34- and 51-year-old females with no family history of tuberous sclerosis complex. Macroscopically, the tumors had white to gray cut surfaces and were microscopically composed of predominantly spindle- to polygon-shaped cells with clear to slightly eosinophilic cytoplasm and pleomorphic nuclei focally arranged in a perivascular pattern, accompanied by marked stromal hyalinization. These tumor cells were immunohistochemically positive for HMB45 and α-smooth muscle actin. Although this variant of PEComa is very rare, this entity should be considered as a potential primary neoplasm of the female genital organs.     

Sclerosing epithelioid fibrosarcoma of the pancreas

Sclerosing epithelioid fibrosarcoma (SEF) is a distinctive variant of fibrosarcoma characterized by epithelioid tumor cells arranged in nests, cords, or sheets embedded within a sclerotic collagenous matrix. It is a relatively newly described malignant fibroblastic tumor, with only fewer than 100 cases reported in English literature. Most cases are located in the lower extremities and limb girdles. Here, we present a case of SEF of the pancreas in a 67-year-old white man and provide a review of literature to date, with emphasis on the differential diagnosis. To our knowledge, this is the first reported case of SEF involving the pancreas.     

Sclerosing epithelioid fibrosarcoma primary of the bone

Sclerosing epithelioid fibrosarcoma (SEF) is an uncommon tumor originally described in soft tissues. We report a case of SEF primary of the left iliac bone in a 42-year-old woman. The tumor was grossly well circumscribed. The histologic examination disclosed a hypocellular neoplasm with densely hyalinized stroma. It was composed predominantly of small-to-moderate-sized round-to-ovoid cells, relatively uniform, often with clear cytoplasm, and arranged in nest, cord, and strand patterns. Because the distinctive morphologic patterns and the immunohistochemical profile of this entity may be mistaken for many different tumors, we here emphasize the differential diagnostic problems of this variant of fibrosarcoma. To our knowledge, this is the first tumor of this kind described in the bone.     

Sclerosing epithelioid fibrosarcoma: a fibrosarcoma with a very long course

Sclerosing epithelioid fibrosarcoma is a rare and slowly growing variant of fibrosarcoma occurring in adults. Its carcinomatous and/or hemangiopericytomatous patterns may mislead to many different tumors. These differential diagnoses are generally ruled out by the clinical data, the morphology and the immunohistochemical study. We report two typical cases of this fibrosarcoma and we highlight the different criterias which are indispensable to make the diagnosis. The very slow course of this disease goes along with a very low proliferative rate, but an accumulation of p53 by immunohistochemistry is paradoxically always founds, even though this accumulation is more often found in highly aggressive sarcomas.     

Low-grade fibromyxoid sarcoma: a clinicopathologic study of 18 cases, including histopathologic relationship with sclerosing epithelioid fibrosarcoma in a subset of cases

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon tumor with diverse histopathologic features. It has been found to be histopathologically and genetically related to hyalinizing spindle cell tumor with giant rosettes. Lately, sclerosing epithelioid fibrosarcoma (SEF) has been identified as another rare variant of fibrosarcoma. Very few studies have addressed the aspect of its histopathologic relationship with LGFMS. The present study was conducted to critically analyze the clinicopathologic features of a series of LGFMS cases, including identification of cases with histopathologic similarity with SEF. During a 7-year period, 18 LGFMS cases were diagnosed in 9 male and 9 female patients, had ages ranging from 10 to 69 years (median, 32.5 years), and were most commonly identified in the lower extremities (8 cases, or 44.4%). Most cases (16, 88.8%) showed “classic” features of LGFMS with mild (13 cases, or 72.2%) to moderate atypia (5 cases) and nil mitosis (12 cases, or 66.6 %). Variable features included whorling tumor growth pattern, small rosettes, perivascular hyalinization, and amianthoid-like collagen, along with epithelioid differentiation and nuclear pseudoinclusions within tumor cells. Four cases (22.2%) with large collagenous rosettes were diagnosed as hyalinizing spindle cell tumor with giant rosettes. Distinct SEF-like areas were observed in 6 cases (33.3%). On immunohistochemistry, consistent vimentin positively reinforced fibroblastic lineage of the tumor. Therapeutically, all 4 of 7 cases with available follow-up details, which underwent wide excisions, have been free of disease at 5 to 61 months. Eight excisions with unclear margins included 3 cases free of disease (24, 36, and 52 months) and 1 case with recurrence and metastasis. Two cases of marginal excision had tumor recurrences, including 1 case that recurred after 10 years. Low-grade fibromyxoid sarcoma is an uncommon sarcoma with diverse histopathologic features. Histopathologic relationship exists between LGFMS and SEF in a few cases. An LGFMS is optimally managed with surgical wide excision and follow-up.     

硬化性上皮样纤维肉瘤的临床病理学观察

目的探讨硬化性上皮样纤维肉瘤的临床病理学特征、免疫表型及鉴别诊断.方法应用光镜和免疫组织化学LSAB法对8例硬化性上皮样纤维肉瘤进行临床病理学分析和免疫表型检测.结果患者均为成年人,男性5例,女性3例,年龄35～54岁(平均45岁).临床上表现为深部软组织内缓慢性生长的肿块,其中大腿/臀部3例,右上臂/肩部2例,胸壁和背部2例,小腿1例.大体上,肿块呈结节状,境界相对清楚,直径2.0～10.5 cm(平均6 em),切面呈灰白色,质地坚韧或有弹性.组织学上,肿瘤由形态一致、小至中等大的圆形或多边形上皮样细胞组成,多呈单个或狭窄的条索状排列,夹杂于大量嗜伊红色、玻璃样变的胶原纤维之间.部分区域中也可排列成巢状、片状或腺泡状.高倍镜下,瘤细胞的胞质透亮或嗜伊红色,核异型性不明显,核分裂象也少见(＜1/10HPF).另在2例肿瘤的局部区域,细胞密度明显增加,核有显著的异型性,核分裂象也易见,类似经典的纤维肉瘤.免疫组织化学标记显示,瘤细胞弥漫强阳性表达波形蛋白,灶性或弱阳性表达上皮膜抗原,不表达细胞角蛋白、S-100蛋白、HMB45、肌动蛋白、结蛋白、CD34、bcl-2、CD30和白细胞共同抗原(LCA)等标记.随访6例,3例复发,1例发生肺部转移.结论硬化性上皮样纤维肉瘤是纤维肉瘤的一种少见亚型,尽管瘤细胞异型性不明显,核分裂象也少见,但肿瘤可发生局部复发及远处转移,临床上应视为一种低至中度恶性的软组织肉瘤处理,组织学上则应注意与一些具有上皮样形态和硬化性间质的肿瘤相鉴别.     

Low-grade fibrosarcoma--report on 39 not otherwise specified cases and comparison with defined low-grade fibrosarcoma types

AIMS: Low-grade fibrosarcomas are tumours that mainly affect the extremities and trunk of adults of either sex. Among these, low-grade fibromyxoid sarcoma (FMS), hyalinizing spindle cell tumour with giant collagen rosettes (HST) and sclerosing epithelioid fibrosarcoma (SEF) are well-established entities. In this study, our aim was to describe a group of low-grade fibrosarcomatous tumours, which could not be encompassed by these entities. These low-grade fibrosarcomas, not otherwise specified (FNOS) were provisionally designated as 'fibrosarcoma, low-grade fibroblastic type'. METHODS AND RESULTS: In the soft tissue tumour registry we found 39 FNOS (46%), 31 FMS (36%), 11 SEF (13%) and four HST (5%). FNOS occurred in older patients than FMS (mean age 56.3 years versus 33.7 years). They mainly showed fibrous features, but myxoid areas could also be seen. While cells tended to be loosely arranged in the myxoid areas, densely packed sheets with a storiform pattern, fascicular arrangements or regions without a defined growth pattern were observed in the fibrous areas. However, neither whirling nor swirling patterns were found. Arcade-like vessels were not visible; pseudolipoblasts did not occur. FNOS exhibited increased atypia and mitotic count compared with the other sarcomas studied [FNOS, mean value 4.6 mitoses/10 high-power field (HPF); FMS, 0.7/10 HPF). Follow-up data were available in 21 FNOS patients. In seven cases (33.3%), local recurrences were reported. Three patients (14.3%) developed metastases and all of them died of tumour. CONCLUSIONS: The term 'fibrosarcoma, low-grade fibroblastic type' should be used as a diagnosis of exclusion. Further studies should elucidate whether it represents a distinct fibrosarcoma type.     

Fibrosarcoma: a review and update

Adult fibrosarcoma, defined by the World Health Organization as a ‘malignant neoplasm composed of fibroblasts with variable collagen production and, in classical cases, a “herringbone” architecture’, is a very rare soft tissue sarcoma. Once considered the most common adult sarcoma, the incidence of adult fibrosarcoma has declined dramatically over the past several decades. This is due to (i) evolution in the classification of soft tissue tumours (ii) recognition of clinically, morphologically and genetically distinctive subtypes of fibrosarcoma and (iii) increased understanding of the many other mesenchymal and non‐mesenchymal tumours that may mimic fibrosarcoma. This review article will summarize the current state of our knowledge about strictly defined adult fibrosarcoma and discuss important entities in its differential diagnosis, including various fibrosarcoma variants, monophasic synovial sarcoma and other potential mesenchymal and non‐mesenchymal mimics.     

18F-fluorodeoxyglucose PET/CT features and correlations with histopathologic characteristics in sclerosing epithelioid fibrosarcoma

Sclerosing epithelioid fibrosarcoma (SEF) is a clinicopathologically distinct variant of fibrosarcoma that is capable of recurrence and metastasis. Awareness of imaging features and histopathologic characteristics will be helpful for differential diagnosis from other common tumors. Here, we report a case of SEF metastasizing to the pancreas as a solitary mass mimicking primary pancreatic cancer, and summarize the reported cases with FDG PET/CT from the literature (n=4). PET/CT showed abnormal FDG accumulation (n=2), mild FDG uptake (n=1), or photopenic (n=1). The FDG PET/CT features are closely related to histopathologic characteristics regarding its differentiation and aggressiveness.