Fine‐needle aspiration cytology of epithelioid malignant peripheral nerve sheath tumor: A case report and review of the literature

The epithelioid variant of malignant peripheral nerve sheath tumor (eMPNST) is an extremely rare soft tissue neoplasm comprising less than 5% of all MPNSTs. It is distinguished cytomorphologically from a conventional MPNST by the presence of polymorphous round epithelioid cells arranged in loose clusters with or without spindled tumor cells. These features pose a diagnostic challenge because the differential diagnosis involves a variety of mesenchymal and non‐mesenchymal tumors including epithelioid sarcoma, sclerosing epithelioid fibrosarcoma, malignant rhabdoid tumor, chordoma, metastatic carcinomas, and melanoma. Thus, it may become imperative to perform immunochemical stains on cell blocks of FNA aspirates to arrive at definitive diagnosis. Reports describing the cytologic features of eMPNST are rare. Herein, we report a case of eMPNST with focus on cytomorphologic and cytoimmunochemical features and differential diagnosis. Diagn. Cytopathol. 2016;44:226–231. © 2015 Wiley Periodicals, Inc.     

Cytohistologic correlations of 24 malignant peripheral nerve sheath tumor (MPNST) in 17 patients: the Institut Curie experience

Cytomorphological patterns of malignant peripheral nerve sheath tumor (MPNST) are insufficiently documented in the literature. Cytological and histological specimens in 24 tumors in 17 patients were correlated. The review of the original cytology reports showed that four (16.6%) tumors were correctly diagnosed, eight (33.3%) were diagnosed as sarcoma not otherwise specified, four (16.7%) as fibrosarcoma, three (12.5%) as synovial sarcoma, three (12.5%) as leiomyosarcoma, and one (4.2%) case each as malignant fibrous histiocytoma and rhabdomyosarcoma. At the review tumors were histologically reclassified as well-differentiated MPNST in 11 (45.9%) cases, anaplastic MPNST in 11 (45.9%) cases, and epithelioid MPNST and malignant Triton tumor in one (4.2%) case each. Cytologically, well-differentiated MPNST were composed of polymorphous oval to round cells, small spindle-shaped cells with wavy and comma-like naked nuclei, and a fibrillary, delicate stroma. Anaplastic MPNST, moreover, were composed of anaplastic giant and polymorphous cells. The malignant Triton tumor was composed of oval to round rhabdomyoblastic cells with eccentric nuclei and the epithelioid MPNST of polymorphous and round, epithelial-like cells. The cytological diagnosis of MPNST may be difficult, especially in anaplastic tumors. The correlation between the cytological features and the clinical information--origin of the tumor from a nerve trunk, a preexisting neurofibroma, patients with known history of neurofibromatosis 1--could be indicative of an MPNST diagnosis.     

Malignant uterine perivascular epithelioid cell tumor: histopathologic and immunohistochemical characterization of a rare tumor in a post-menopausal woman

Background: Perivascular epithelioid cell tumors (PEComas) are rare, mesenchymal neoplasms composed of epithelioid cells exhibiting myogenic and melanocytic differentiation. The uterus is an infrequent site of involvement. The most common histopathologic mimics include leiomyosarcoma, endometrial stromal sarcoma, undifferentiated uterine sarcoma, and malignant melanoma. Rendering an accurate histopathologic diagnosis is essential, owing to the prognostic and therapeutic implications. Case: A 65-years-old post-menopausal woman presented with post-menopausal bleeding, abdominal pain, and heaviness for the last four months. Ultrasound abdomen revealed a large uterine mass replacing the endometrial cavity. She underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. Result: Microscopically, a circumscribed tumor with tumor cells arranged in sheets and interlacing fascicles, with interspersed fine capillary network, was seen. The individual tumor cells were epithelioid to spindle with moderate pleomorphism, round nuclei, vesicular chromatin, prominent macronucleoli, and moderate cytoplasm. Mitosis was 2-3/50 HPFs. On immunohistochemistry, tumor cells were positive for HMB-45, Melan-A, and smooth muscle actin and were negative for h-caldesmon, TFE3, S-100, CD10, and pan-cytokeratin. Based on the histopathologic and immunohistochemical features, a final diagnosis of malignant uterine PEComa was rendered. Conclusions: This index report describes the characteristic histopathologic and immunohistochemical features of malignant uterine PEComa and highlights the salient features that distinguish it from other commonly encountered histopathologic mimics.     

Clinicopathologic features and immunohistochemical spectrum of 11 cases of epithelioid malignant peripheral nerve sheath tumors,including INI1/SMARCB1 results and BRAF V600E analysis

Epithelioid malignant peripheral nerve sheath tumor (MPNST) is a rare, relatively less chemosensitive sarcoma. We report clinicopathologic features of 11 epithelioid MPNSTs, including rare forms, along with INI1 immunostaining and BRAF V600E mutation results. BRAF V600E mutation was tested by Real‐time polymerase chain reaction (PCR) technique. Eleven tumors occurred in six men and five women (M:F ratio = 0.85:1) within an age range of 5–73 years (average = 44), mostly in lower limbs (five), followed by upper limbs (four). Tumor size (n = 6), varied from 3.1 to 15 cm (average = 8.3). Histopathologically, most tumors were multilobular, characterized by epithelioid to round‐shaped, malignant cells, along with spindle cells (three cases), “rhabdoid‐like” cells (seven cases) and pleomorphic giant cells (single case). By immunohistochemistry, tumor cells were positive for S100 protein (11/11) (100%), EMA (3/7) (42.8%), pan CK(2/7) (28.5%), and HMB45 (1/11) (9%), while these were negative for Melan A (0/11) and INI1 (3/11), including a single tumor, displaying HMB45 positivity. BRAF V600E mutation was positive in 1/8 cases, that lacked melanocytic marker expression. All patients (n = 5) were treated by surgical resection. During follow‐up (n = 8, median duration = 23 months), four patients developed tumor recurrences and four developed metastasis, mostly to lymph nodes (3). Finally, four patients were alive with disease, two were alive with no evidence of disease, and two patients died of disease. Epithelioid MPNSTs have a diverse histopathologic spectrum. Loss of INI1 is useful, including in identifying rare forms of epithelioid MPNST, displaying melanocytic differentiation. Most tumors are treated by surgical resection. Loss of INI1 and the presence of BRAF V600E mutation in some cases raises future possibility of exploring targeted therapy in those, rare epithelioid MPNSTs.     

Fine-needle aspiration of epithelioid malignant peripheral nerve sheath tumor (epithelioid malignant schwannoma)

The epithelioid variant of malignant peripheral nerve sheath tumor (MPNST), also known as malignant epithelioid schwannoma, is a relatively rare and recently characterized clinicopathologic entity. The epithelioid variant of MPNST shares many clinical features with conventional MPNST but is characterized by different histologic and cytologic features. These include a distinctive nesting pattern and an abundance of cytoplasm not seen in histology of conventional nerve sheath tumors. Cytologically, the epitheliod variant shows a propensity to cellular discohesiveness and a plasmacytoid or epitheliod appearance that is in contradistinction to the spindled appearance of the usual MPNST. Herein, we report our experience with fine-needle aspiration (FNA) of two epithelioid malignant schwannomas and discuss the FNA cytologic differential diagnosis. Diagn. Cytopathol. 1997;17:200–204. © 1997 Wiley-Liss, Inc.     

子宫血管周上皮样细胞肿瘤临床病理观察

目的研究子宫血管周上皮样细胞肿瘤的病理学特征、诊断、鉴别诊断和生物学行为。方法对5例子宫血管周上皮样细胞肿瘤进行常规组织学和免疫组织化学（SP法）染色和观察,对患者进行随访,并复习相关文献。结果光镜下5例肿瘤均由透明或嗜酸细胞巢或宽窄不等的细胞索组成,间质有丰富的小血管和程度不等的透明变。免疫组织化学染色示5例瘤细胞均黑色素细胞标记阳性和程度不等的结蛋白和平滑肌肌动蛋白（SMA）阳性,CK和CD10阴性。5例患者现均存活。结论子宫血管周上皮样细胞肿瘤具有较特征性的组织病理及免疫组织化学特点,HMB45阳性对诊断有重要作用。该肿瘤分良性、恶性潜能不能确定和恶性三类,应与透明细胞癌和上皮样平滑肌肿瘤区别。     

Intracranial MPNST with Multivacuolated Cells and Hyaline Globules: A Case with Ultrastructural Findings

A case of intracranial malignant peripheral nerve sheath tumor (MPNST) with uncommon features due to recurrence is reported. The primary tumor showed typical histopathological features of MPNST with wavy nuclei and S-100 positivity. The patient’s latest recurrent tumor resembled undifferentiated sarcoma with lipoblast-like multivacuolated cells and hyaline globules (HGs). Ultrastructurally, the vacuolated spaces contained granular materials derived from cystic dilation of the rough endoplasmic reticulum. The HG consisted of round osmophilic inclusions with or without a limiting membrane. The HGs and lipoblast-like multivacuolated cells may have been caused by the degeneration of tumor cells in myxoid stroma and abundant vasculature.     

Purely epithelioid malignant peripheral nerve sheath tumor of the vulva.

Primary malignant peripheral nerve sheath tumors(MPNST) of the vulva are extremely rare and most of them are composed of a spindle cell component. A few cases of MPNST containing partially or purely epithelioid cells have been reported. Purely epithelioid MPNST differ from the ordinary epithelioid MPNST due to the absence of a spindle cell component. We present the first case of purely epithelioid MPNST arising in the vulva reviewing in the world literature without definite evidence of von Recklinghausen''s disease or nerve involvement. The patient was a 63-year-old woman with a palpable vulvar mass, 6 x 4 x 1.5 cm in dimension, was not encapsulated but well-demarcated, ovoid and rubbery and showed pale yellow, homogeneous, fish-flesh appearance with focal cystic changes on cut surface. The histologic features consisted of solely epithelioid cells which were arranged in tight clusters or cords with solid growing pattern and focally scattered rosette-like structures. According to the immunohistochemical results, most of tumor cells were strongly positive for neuron specific enolase, and some of them were weakly positive for S-100 protein and vimentin. We considered that purely epithelioid MPNST would represent a certain degree of differentiation toward nerve or neuronal cells rather than Schwann cells.     

Intraosseous epithelioid malignant peripheral nerve sheath tumor of the phalanx. Case report

We report the first case of intraosseous epithelioid malignant peripheral nerve sheath tumor (MPNST) occurring in the phalanx. The patient was a 50-year-old Japanese man with an intramedullary lytic lesion of the proximal phalanx. Microscopically, the tumor was composed of epithelioid cells or polygonal cells, forming large cell nests with central necrosis. Most tumor cells were diffusely and strongly immunopositive for S-100 protein and vimentin, and negative for cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, alpha-smooth muscle actin, and HMB-45. Laminin-positive material was discontinuously demonstrated between the individual tumor cells. Electron microscopy showed prominent external lamina. Our case indicated that laminin is useful for differentiating epithelioid MPNST from metastatic carcinoma and malignant melanoma.     

Synchronous uterine carcinosarcoma and contralateral breast cancer after tamoxifen therapy: a case report

Uterine carcinosarcoma (malignant mixed Müllerian tumor, MMMT) is a rare aggressive malignant tumor, which demonstrates both malignant epithelial (carcinoma) and mesenchymal (sarcoma) components. Synchronous uterine carcinosarcoma and contralateral breast cancer in patient received tamoxifen treatment had not been reported. We present a case of uterine carcinosarcoma co-occurrenced with contralateral breast cancer in a 56-year-old nulliparous, obese breast cancer patient, who had been treated with tamoxifen for 5 years. The patient presented with palpable pelvic mass and vaginal bleeding. Histopathological evidence revealed that the tumor was comprised of an admixture of malignant epithelial and mesenchymal components. The epithelial component was endometrioid type adenocarcinoma, while sarcomatous component had heterologous elements including fusiform cell sarcoma and a prominent component of cartilage. The infiltrating ductal carcinoma has been diagnosed on her right breast. The patient died of disease 8 months after diagnosis. Postmenopausal patients, with adjuvant tamoxifen treatment for breast cancer, are at increased risk for the development of uterine carcinosarcoma and less benefit for contralateral breast cancer.     

Fine-needle aspiration cytology and core biopsy of malignant peripheral nerve sheath tumor of the uterus: a case report

Malignant peripheral nerve sheath tumor (MPNST) is an uncommon mesenchymal neoplasm of neural origin. MPNST arising in the uterus is extremely rare. Its histologic appearance on this anatomical location has been only rarely reported. A 62-yr-old woman with a previous history of partial hysterectomy presented with a large pelvic mass in the uterine stump. Fine-needle aspiration (FNA) and core biopsy were obtained under ultrasonographic guidance, and the diagnosis of MPNST was established. The cytologic and histologic findings were consistent with a spindle-cell neoplasm suggestive of MPNST. The tumor cells were focally positive for S-100 protein immunostain, thus providing further support for the neoplasm's nerve sheath differentiation. The patient had no history of von Recklinghausen's disease. Resection of the mass confirmed the diagnosis of MPNST. To our knowledge, the FNA cytology of MPNST in this unusual location has not been previously reported. FNA cytology, along with core biopsy and immunochemistry, is a reliable tool in the diagnosis of MPNST.     

Primary alveolar soft part sarcoma of the uterine cervix: a case report and literature review

Alveolar soft part sarcoma (ASPS) is a tumor of unknown histogenesis, composed of large, epithelioid cells with eosinophilic cytoplasm, having an alveolar pattern. Primary ASPS of uterine cervix is very rare. In this report, we present a 21-aged-old female with primary ASPS in the uterine cervix and discuss the clinicopathological characteristics, immunophenotype, molecular genetic feature and differential diagnosis of ASPS of cervix.     

Intra-abdominal follicular dendritic cell sarcoma with marked pleomorphic features and aberrant expression of neuroendocrine markers: report of a case with immunohistochemical analysis.

Follicular dendritic cell sarcoma (FDCS) is a very rare malignant tumor arising most frequently in lymph nodes with only few reports of extranodal locations. We report the case of a 35-year-old man with a large retroperitoneal mass. Histologically the tumor was composed of highly pleomorphic cells exhibiting some uncommon features such as an epithelioid appearance, cystic spaces, and multinucleated cells with morphologic features of emperipolesis. Immunohistochemically the neoplastic cells were immunoreactive for CD21, CD23 and CD35. A previously unreported expression of neuroendocrine markers (Synaptophisyn and Neuron-Specific-Enolase) was present. Ultrastructurally no neuroendocrine secretory granules were detected. FDCS can mimic a wide variety of other malignant tumors, and a correct diagnosis requires exclusion of other neoplasms and immunohistochemical confirmation.     

Intracranial MPNST with multivacuolated cells and hyaline globules: a case with ultrastructural findings

A case of intracranial malignant peripheral nerve sheath tumor (MPNST) with uncommon features due to recurrence is reported. The primary tumor showed typical histopathological features of MPNST with wavy nuclei and S-100 positivity. The patient's latest recurrent tumor resembled undifferentiated sarcoma with lipoblast-like multivacuolated cells and hyaline globules (HGs). Ultrastructurally, the vacuolated spaces contained granular materials derived from cystic dilation of the rough endoplasmic reticulum. The HG consisted of round osmophilic inclusions with or without a limiting membrane. The HGs and lipoblast-like multivacuolated cells may have been caused by the degeneration of tumor cells in myxoid stroma and abundant vasculature.     

Myxoid Variant of Epithelioid Leiomyosarcoma of the Uterus

A rare case of myxoid variant of epithelioid leiomyosarcoma of the uterus in a 76-year-old woman is reported. Palpation and computed tomography revealed an enlarged uterus. Total hysterectomy and bilateral salpingo-oophorectomy were performed, and a hemispheric tumor, measuring 2.7 X 2.5 X 1.8 cm, was found protruding into the uterine cavity of the upper uterine segment. The tumor contained a prominent myxoid stroma and epithelioid tumor cells, which were round and polygonal in shape and showed positive immunoreactivity for desmin and vimentin. High mitotic activity was observed in the tumor cells. Electron microscopic examination revealed bundles of filaments in the cytoplasm and fine reticular material in the extracellular matrix. Histochemically, the myxoid stroma contained abundant acid mucopolysaccharide. The tumor cells were considered to originate from smooth muscle cells, while the myxoid stroma expressed varying differentiation of uterine mesenchymal cells. The patient is currently well with no evidence of recurrence or metastasis one year after the operation. Acta Pathol Jpn 41: 778-783, 1991.     

Establishment and characterization of a novel human malignant peripheral nerve sheath tumor cell line,FMS-1, that overexpresses epidermal growth factor receptor and cyclooxygenase-2

Malignant peripheral nerve sheath tumor (MPNST) is a rare soft tissue sarcoma. We established a new human MPNST cell line (designated FMS-1) from MPNST of the right brachial plexus of a 69-year-old woman with NF1. The cell line has been maintained for >24 months with >100 passages. FMS-1 cells showed a fibrosarcoma-like or epithelioid pattern in the heterotransplanted tumor, compared with a fascicular growth pattern of short-spindle tumor cells in the primary tumor. Immunophenotypically, FMS-1 cells showed almost the same characteristics as the primary tumor. Cytogenetic and molecular analyses revealed a deletion in exons 5-8 of the p53 gene. Epidermal growth factor receptor (EGFR) and cyclooxygenase (COX)-2 were expressed in FMS-1 cells. To improve the highly aggressive course and poor prognosis and establish new therapeutic methods, molecular genetic and biological characterizations of MPNST are required. Thus, FMS-1 cells might be useful for investigating biological behaviors and developing new molecular-targeting antitumor drugs for MPNST expressing EGFR or COX-2.     

Primary non-Hodgkin's lymphoma of the uterine cervix mimicking leiomyoma: case report and review of the literature

Primary malignant lymphoma occurring in the uterine cervix is a rare event. We report a case of primary non-Hodgkin's lymphoma of the uterine cervix mimicking leiomyoma. The immunophenotype of the tumor and the differential diagnostic approach to this uncommon malignancy also are presented.     

Infrequent SMARCB1/INI1 gene alteration in epithelioid sarcoma: a useful tool in distinguishing epithelioid sarcoma from malignant rhabdoid tumor

Loss of SMARCB1/INI1 protein expression is considered useful for confirming a histologic diagnosis of malignant rhabdoid tumor. However, loss of SMARCB1/INI1 protein expression has recently been reported in other tumors as well, including a few cases of epithelioid sarcoma. In addition, the histopathologic differences between proximal-type epithelioid sarcoma and malignant rhabdoid tumor have not been conclusively defined. We analyzed SMARCB1/INI1 protein expression in 54 epithelioid sarcoma (proximal-type, 25; distal-type, 29) and examined alterations of the SMARCB1/INI1 gene in the cases lacking protein expression. We found that 19 (76.0%) proximal-type epithelioid sarcoma and 27 (93.1%) distal-type epithelioid sarcoma showed loss of SMARCB1/INI1 protein expression. Analysis of 39 cases with loss of protein expression revealed 4 cases (10.3%) with SMARCB1/INI1 gene alterations at the DNA level (homozygous deletion, 2; 1- or 2-bp deletion, 2) that could have induced the loss of gene products, and all 4 of these were proximal-type epithelioid sarcoma. Epithelioid sarcoma was thus associated with a high frequency of loss of SMARCB1/INI1 protein expression similar to that in malignant rhabdoid tumor. However, the frequency of SMARCB1/INI1 gene alteration at the DNA level in proximal-type epithelioid sarcoma was significantly lower than that in malignant rhabdoid tumor. In addition, the prognosis of patients with malignant rhabdoid tumor is significantly worse than that of patients with proximal-type epithelioid sarcoma (P = .001). Therefore, proximal-type epithelioid sarcoma and malignant rhabdoid tumor are suggested to be distinctive tumors with respect to the mechanism of the loss of SMARCB1/INI1 protein expression. Analysis of alterations in the SMARCB1/INI1 gene may thus be a useful diagnostic tool to distinguish proximal-type epithelioid sarcoma from malignant rhabdoid tumor.     

Malignant peripheral nerve sheath tumor with perineurial cell differentiation (malignant perineurioma)

A unique case of malignant peripheral nerve sheath tumor (MPNST) with perineurial cell differentiation occurring in a 63-year-old woman in a subcutis of the forearm is described. The tumor contained cellular and myxoid areas. The neoplastic cells were fusiform with distinct cell borders. They were arranged in storiform pattern and in wavy parallel cell cords in the cellular areas. Focally, a pleomorphism and mitotic activity (including atypical mitoses) similar to those of malignant fibrous histiocytoma were seen. The myxoid parts contained haphazardly oriented cells and scarce lipoblast-like multivacuolated cells mimicking a liposarcoma. In the differential diagnosis, myxoid liposarcoma, dermatofibrosarcoma protuberans, malignant fibrous histiocytoma and low-grade fibromyxoid sarcoma were considered. Immunohistochemically, perineurial differentiation was indicated by the diffuse expression of epithelial membrane antigen and focal reactivity for CD34. The tumor was negative with antibodies to S-100 protein, Leu-7, CD68 (KP1), vimentin and cytokeratin AE1/AE3. Ultrastructure of tumor cells revealed features of MPNST. No recurrence occurred in the patient during 2 years follow up.     

Dramatic response to entrectinib in a patient with malignant peripheral nerve sheath tumor harboring novel SNRNP70-NTRK3 fusion gene

Neurotropic tropomyosin receptor kinase (NTRK) gene rearrangements have been reported in limited cases of sarcomas; however, to date, there has been only one report of such rearrangements in malignant peripheral nerve sheath tumors (MPNSTs). Herein, we describe a 51-year-old male patient with a buttock tumor arising from the sciatic nerve, which was diagnosed as MPNST with positive S-100 staining, negative SOX10 staining, and loss of trimethylation at lysine 27 of histone H3 (H3K27me3) confirmed by immunohistochemistry. Soon after the resection of the primary tumor, the patient was found to have pulmonary and lymph node metastases. Chemotherapy with eribulin and trabectedin showed limited effects. However, the patient responded rapidly to pazopanib, but severe side effects caused discontinuation of the treatment. RNA panel testing revealed a novel fusion gene between Small Nuclear Ribonucleoprotein U1 Subunit 70 (SNRNP70) gene and NTRK3 gene. Furthermore, loss of NF1, SUZ12, and CDKN2A genes was confirmed by DNA panel testing, which is compatible with a histological diagnosis of MPNST. SNRNP70 possesses a coiled-coiled domain and seems to induce constitutive activation of NTRK3 through dimerization. In fact, immunohistochemistry revealed diffuse staining of pan-TRK within tumor cells. Treatment with entrectinib, which is an NTRK inhibitor, showed a quick and durable response for 10 months. Although NTRK rearrangements are very rare in MPNST, this case highlights the importance of genetic testing in MPNST, especially using an RNA panel for the detection of rare fusion genes.