Mixed Tumors, Myoepitheliomas, and Oncocytomas of the Soft Tissues Are Likely Members of the Same Family: A Clinicopathologic and Ultrastructural Study

Four diagnostically unusual soft tissue tumors are presented. All lesions were of consistent size and long duration. Histologically, one lesion was analogous to mixed tumors of the usual sites (i.e., salivary glands), one lesion was totally spindled, and the two other lesions both had oncocytic appearances ( epithelioid and spindle biphasic pattern in a case, purely epithelioid in the other). Immunohistochemically, the mixed tumor was positive for vimentin, cytokeratins, S-100 protein, and focally for EMA. The purely spindled tumor exhibited immunoreactivity for vimentin, actins, S-100 protein, EMA (focally), and GFAP. The oncocytic biphasic tumor was positive for mitochondrial antigen, vimentin, and actins. The purely epithelioid oncocytic neoplasm was immunoreactive only for mitochondrial antigen and vimentin. Ultrastructurally, in the epithelial-like portion of the first (mixed) tumor, peripheral arrays of contractile filaments were detected along with well-developed desmosomes. In the second (spindled) case, peripheral contractile filaments and attenuated desmosomes were also seen. In the third case, a huge number of mitochondria, some desmosomes, and actin-type microfilaments were found. In the fourth case, desmosomes and punctate subplasmalemmal densities, in addition to numerous mitochondria, were documented. In all cases an external basal lamina were present, which was discontinuous in the first three cases and almost continuous in the fourth. These tumors were respectively designated as mixed tumor, myoepithelioma of the classic type, myoepithelioma of oncocytic type with biphasic cell architecture, and true oncocytoma. So far, all tumors have followed benign clinical courses (median follow up: 12 months). Comparisons with similar tumors of other sites are drawn, and suggestions for considering all of them as members of the same myoepithelial-derived tumor family are given.     

Localized fibrous tumors of the pleura: correlation of histopathological, immunohistochemical and ultrastructural features.

The histogenesis of localized fibrous tumor of the pleura (LFTP) is controversial. We studied 12 LFTP's by light microscopy; by immunohistochemical staining for cytokeratin (CK), vimentin, muscle-specific actin, desmin, S-100 protein, epithelial membrane antigen (EMA) and factor VIII; by electron microscopy in 6 tumors; and by lung digestion for asbestos bodies in 4 cases. Three histologic patterns occurred in combination: 1) collagenous, 2) cellular and 3) hypocellular/myxoid. Hemangiopericytoma-like foci were prominent in the cellular areas of 9 tumors. Unusual features included diffuse small cells in 3 tumors, microcystic foci in 2, macrocystic areas in 5 and tumor giant cells in 4 tumors. Neoplastic cells in all patterns stained positively for vimentin and actin in 9 and 4 tumors, respectively, and were negative for all other markers. CK and EMA were identified in mesothelial and epithelial invaginations only. Ultrastructurally, neoplastic cells demonstrated intercellular junctions, intermediate or thin filaments, dense bodies and rough endoplasmic reticulum. Basal lamina was focally present in 5 tumors, while tonofilaments, desmosomes and short microvilli were observed in one case. Our results support the conclusion that LFTP is a neoplasm of the multipotential subserosal cell, and usually expresses mesenchymal (fibroblastic/myofibroblastic) differentiation. Coexpression of mesothelial features is rare. Lung asbestos body quantitation in 4 patients suggests that there is no association between LFTP and asbestos exposure.     

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.     

Cutaneous myoepithelioma: a clinicopathologic and immunohistochemical study of 14 cases

Analogous to mixed tumors of salivary glands (" pleomorphic adenomas" ), cutaneous mixed tumors (" chondroid syringomas" ) contain a ductal (epithelial) component and a variably prominent myoepithelial component. Tumors showing purely myoepithelial differentiation (myoepitheliomas) have only recently been recognized to arise in the dermis, and to date very few cases have been described. To characterize these tumors further, 14 cutaneous myoepithelial tumors were retrieved from the authors' consult files. Eleven patients were male and 3 were female; their median age was 22.5 years (range, 10 to 63 years), and 7 patients were between 10 and 20 years old. Tumor size ranged from 0.5 to 2.5 cm (mean, 1.1 cm). Most tumors arose on the extremities: 6 on the upper limbs, 6 on the lower limbs, and 1 each on the back and nose. Ten tumors were limited to the dermis, and 5 also extended into superficial subcutis. Thirteen tumors were myoepitheliomas (lacking ductal differentiation), and 1 tumor was a myoepithelial carcinoma (exhibiting severe cytological atypia and a high mitotic rate). Histologically, 7 tumors were solid, composed of ovoid to spindled, histiocytoid, or epithelioid cells with no significant stroma, and 7 were predominantly lobulated, with cords or nests of epithelioid, plasmacytoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. One tumor was composed solely of plasmacytoid (hyaline) cells, and 1 exhibited extensive adipocytic differentiation. Among the 13 myoepitheliomas, mitoses ranged from 0 to 6 per 10 high-power fields (HPFs) (mean, 1.5); 8 tumors contained no mitoses. The myoepithelial carcinoma had 39 mitoses per 10 HPFs. By immunohistochemistry, all cases were reactive for epithelial markers (keratins and/or epithelial membrane antigen [EMA]); 13 of 14 (93%) expressed S-100 protein, 10 of 11 expressed (91%) calponin, 11 of 14 (79%) expressed EMA, 9 of 14 (64%) expressed keratins, 8 of 14 (57%) expressed smooth muscle actin, 7 of 14 (50%) expressed glial fibrillary acidic protein, 3 of 11 (27%) expressed p63, and 1 of 6 (17%) expressed desmin. All 5 cases without keratin staining were diffusely positive for EMA, and all of these cases showed a solid growth pattern. Follow-up was available for 8 patients (median follow-up, 40 months; range, 6 months to 9 years); 3 tumors (38%) recurred locally, and 1 tumor (13%) also metastasized to the lymph nodes. The case that resulted in recurrence and metastasis had the highest mitotic rate (6 per 10 HPFs) of the cytologically benign tumors. Follow-up information was not available for the myoepithelial carcinoma. This study suggests that approximately 50% of cutaneous myoepitheliomas are distinctive lesions composed of a solid proliferation of cells with abundant eosinophilic syncytial cytoplasm, which often lack immunostaining for keratin, whereas the remainder demonstrate focally reticular architecture and myxoid stroma or plasmacytoid cells, similar to their counterparts in salivary gland and soft tissue. Whereas most cutaneous myoepitheliomas behave in a benign fashion, there is apparently a significant risk for local recurrence but a low metastatic potential.     

Ovarian small cell carcinoma. Histogenetic considerations based on immunohistochemical and other findings

Small cell carcinoma of the ovary is a rare, poorly understood aggressive tumor of young women, associated with paraendocrine hypercalcemia in two-thirds of the cases. Immunohistochemical staining of 15 small cell carcinomas, one-third of which were associated with hypercalcemia, 15 adult granulosa cell tumors, 15 juvenile granulosa cell tumors, and 5 Sertoli cell tumors, was performed with the use of antibodies against cytokeratins (AE-1/AE-3, CAM 5.2, 902), epithelial tumor-associated antigens (B72.3, epithelial membrane antigen [EMA]), vimentin, S-100, neuron-specific enolase (NSE), lysozyme, parathyroid hormone, and chromogranin-A in an attempt to define histogenetically this tumor type. One-third of the small cell carcinomas were positive for EMA, whereas all of them were negative for B72.3 and S-100. In contrast, one-third of the granulosa cell tumors were positive for S-100 and all of them were negative for EMA and B72.3. One of five Sertoli cell tumors were positive for EMA and two were positive for B72.3, but all were negative for S-100. Differences existed in the frequency, intensity, and/or pattern of staining for cytokeratin, vimentin, lysozyme, and NSE among the various tumor types. A single small cell carcinoma from a patient with hypercalcemia stained focally for parathyroid hormone, whereas all 30 granulosa cell tumors and 4 of 5 Sertoli cell tumors were nonreactive. Chromogranin-A staining was noted in four of five small cell carcinomas, none of ten granulosa cell tumors, and two of five Sertoli cell tumors. These immunohistochemical findings, as well as previous light and electron microscopic data, do not clearly indicate any specific cell as the cell of origin of the ovarian small cell carcinoma.     

肾透明细胞肉瘤的临床病理及免疫表型特征

目的 探讨肾透明细胞肉瘤（clear cell sarcoma of the kidney,CCSK）的临床病理特点、免疫表型特征及鉴别诊断。方法 应用HE和免疫组化vimentin、bcl-2、desmin、S-100蛋白、CD99、CD34、CDll7、CK、EMA染色,观察2例CCSK的病理组织学形态,并复习文献。结果 镜下见瘤细胞为上皮样或短梭形,被分枝状纤维血管间质分隔成巢团状,部分区域见黏液样变性微囊肿和细胞外胶原玻璃样变类似骨样组织的硬化型等形态变异。免疫组化示：瘤细胞vimentin和bcl-2弥漫阳性,余为阴性。结论 CCSK是一种罕见的儿童期恶性肾肿瘤,诊断主要依靠组织病理学和免疫组化,熟悉其形态学变异有利于与其它类似病变如肾母细胞瘤、先天性中胚叶肾瘤、肾恶性横纹肌样瘤、原始神经外胚叶肿瘤等鉴别。     

Epithelioid variant of pleomorphic liposarcoma: a study of 12 cases of a distinctive variant of high-grade liposarcoma.

We describe 12 patients with a distinctive variant of pleomorphic liposarcoma that histologically shows epithelioid features and focally resembles a solid carcinoma. The tumors occurred in nine men and three women (median age, 63 yr; range, 40-78 yr). Five tumors were in the thigh, two in the chest wall, two in the axilla, and one each in the retroperitoneum, groin, and calf. Most were 15 to 20 cm in maximal diameter. They consisted of sheets of epithelioid-appearing cells with ample, variably eosinophilic cytoplasm, often showing a honeycomb-like pattern of cell borders and little if any collagenous extracellular matrix. Their histologic features often resembled those of renal clear cell carcinoma or adrenal cortical carcinoma, but all showed evidence of adipocytic differentiation, and five also showed focal spindle cell components. One patient whose tumor in the thigh had been originally diagnosed as metastatic renal carcinoma had undergone nephrectomy without a finding of a kidney tumor. All of the cases were positive for vimentin; 6 of 11 cases were positive for S-100 protein, usually focally; 5 of 11 were focally positive for keratins; and all were negative for epithelial membrane antigen, muscle actins, desmin, and CD34. High mitotic activity (mean, 42 mitotic figures per 10 high power fields) and high MIB-1-positive proliferative fraction (>30%) were seen in all of the cases, and nuclear p53 immunoreactivity was detected in five of seven cases. Of the eight patients with complete follow-up, five died of disease (median survival, 6 mo), two died of unrelated causes 10 and 18 years later, and 1 was alive and well 24 years later. The epithelioid variant of pleomorphic liposarcoma is a high-grade tumor that must be distinguished from malignant epithelial tumors, especially in view of the keratin immunoreactivity of some of these neoplasms.     

A SMARCB1-deficient vulvar neoplasm with prominent myxoid stroma: report of a case showing ERG and FLI1 expression

In the vulvar region, epithelioid sarcoma (ES) is the most frequent SMARCB1-deficient neoplasm, followed by myoepithelial carcinoma (MC). Previous studies have demonstrated that some SMARCB1-deficient vulvar neoplasms cannot be classified as either ES or MC. Herein, we report of a 42-year-old woman with a SMARCB1-deficient neoplasm with prominent myxoid stroma in the vulva. It contained both epithelioid and spindled tumor cells, both of which showed vimentin and EMA expression. Although other markers useful for the differential diagnosis among SMARCB1-deficient tumors were negative, this tumor displayed characteristic expression of ERG and FLI1. As there are no reliable data regarding expression of ERG and FLI1 in MC, which are demonstrated to be often expressed in ES, further classification of cases such as the one reported here requires reliable data regarding their expression status in MC.     

Pleomorphic adenoma with a predominantly myoepithelial proliferation of the vagina

A case of pleomorphic adenoma of the vagina in a 44-year-old woman was described. The tumor was a submucosal mass measuring 3.5 X 2 X 2 cm and located in the left lateral wall 1.5 cm inside the introitus. Histologically, it was predominantly composed of sheets and strands of spindle-shaped or polygonal cells focally dispersed in the myxoid tissue to form pseudomicrocysts. Ultrastructure demonstrated the basal lamina, desmosomes, variable amounts of filaments of both intermediate and microfilament, and occasionally microvilli in these tumor cells indicating that dominant cells were myoepithelial in nature. With immunohistochemical studies, keratin and cytokeratin were positive, whereas, S-100 protein, glial fibrillary acidic protein, vimentin, secretory component, and lysozyme were negative. The previously published cases were reviewed and compared with the present case.     

Symptomatic Intraspinal Oncocytic Adrenocortical Adenoma

Most intraspinal neoplasms of epithelial origin are metastases from primary carcinomas. Benign epithelial tumors are rarely found at this site. We here present the case of a 44-year-old woman with a lesion in the cauda equina that fulfilled the radiologic criteria of schwannoma and caused clinical symptoms for 3 years. The excised tumor was composed of nests of large polygonal cells with eosinophilic partial granular cytoplasm. Significant atypia, necrosis, and mitosis were absent from this lesion. The tumor showed diffuse positivity for melan-A, synaptophysin, and alpha-inhibin. Steroidogenic factor 1 and cytokeratins 8 and 18 were focally seen in the absence of S-100 and chromogranin. This immunoprofile indicated adrenocortical origin. Ultrastructural examination showed abundant mitochondria, suggesting an oncocytic tumor. The diagnosis of an oncocytic adrenal cortical adenoma was made. These extraadrenal tumors are thought to arise from heterotopic adrenocortical tissue in the spinal cavity. Oncocytic tumors are rare neoplasms and they comprise non-functioning variants of adrenal cortical adenomas. To date, only five such intraspinal tumors have been observed. Immunohistochemistry excluded oncocytic paraganglioma, oncocytic meningioma, renal cell carcinoma, alveolar soft part sarcoma, and granular cell tumor. A view of the literature of these rare but probably underdiagnosed intraspinal tumors is given.     

Sarcomatoid salivary duct carcinoma of the parotid gland

Salivary duct carcinoma (SDC) is a high-grade neoplasm known to histologically resemble high-grade ductal carcinoma in situ of the breast. We describe 3 cases of sarcomatoid salivary duct carcinoma, a heretofore unreported variant of SDC. Each case was a composite of SDC and sarcomatoid carcinoma and histologically similar to reported cases arising in the breast. The clinicopathologic features, including immunohistochemistry, of 3 cases were investigated. In the 3 men, ages 56, 68, and 70 years, the resected parotid tumors measured 1.5, 3.5, and 1.5 cm, respectively. Only the 3.5-cm tumor extended beyond the parotid gland into soft tissue. This patient died at 3 years with pulmonary metastases. The other patients were free of disease at 6 and 12 months. Histologically, each case was a composite of usual-type SDC and sarcomatoid carcinoma. SDC showed typical cribriform architecture, whereas anaplastic, spindled cells constituted the sarcomatoid areas. Immunohistochemically, epithelial elements stained as follows: cytokeratin (AE1/AE3 & CAM 5.2) positive in 3 of 3 cases, EMA positive in 3 of 3 cases, vimentin negative in 3 of 3 cases, desmin negative in 3 of 3 cases, c-erbB-2 positive in 1 of 2 cases. Sarcomatoid elements stained as follows: AE1/AE3 negative in 3 of 3 cases, CAM 5.2 rare positive cell in 1 of 3 cases, EMA focally positive in 3 of 3 cases, vimentin positive in 3 of 3 cases, desmin negative in 3 of 3 cases, c-erbB-2 negative in 2 of 2 cases. Electron microscopy, performed in one case, showed scattered junctional complexes congruent with epithelial differentiation. Immunohistochemical results, EMA and CAM 5.2 positivity, and ultrastructural findings supported our belief that these unique biphasic tumors represented SDC with sarcomatoid carcinoma. We conclude an element of sarcomatoid carcinoma rarely may arise in association with SDC, and it is erroneous to diagnose such tumors as "carcinosarcoma."     

Proximal-type epithelioid sarcoma of the vulva with INI1 diagnostic utility

Proximal epithelioid sarcoma (PES) is an extremely uncommon neoplasm of the vulva with an aggressive behavior. Recently, these authors experienced a case of proximal-type ES in a 41-year-old woman who was admitted for a rapidly growing mass in the right mons pubis. An about-1-cm-sized mass was initially noticed one and a half years earlier. The excised mass, however, was 8 cm in greatest dimension and was relatively well circumscribed. The cut surface was trabeculated, with multifocal hemorrhages and necroses. Microscopically, the tumor consisted of epithelioid rhabdoid cells with vesicular nuclei, large prominent nucleoli, and cytoplasmic eosinophilic globules comparted by thin, fibrous septae. The main differential diagnoses included PES, other sarcomas with epithelioid cells, malignant melanoma, and sarcomatoid carcinoma. The tumor cells were diffusely positive for vimentin and EMA; focally positive for cytokeratin; and negative for CK5/6, CD34, S-100 protein, desmin, and myogenin. INI1 (hSNF5/SMARCB1, a member of the SW1/SNF chromatin remodeling complex located on chromosome 22q11.2) staining clearly showed loss of expression in the tumor cells. Recent studies reported that some ESs also showed INI1 inactivation, as characteristically seen in malignant rhabdoid tumors of infancy. Reported herein is the diagnostic utility of INI-1 on PES and the possible relationship between PES and malignant rhabdoid tumor of the soft tissue, besides a collective review of the reported cases of PES of the vulva and of the current case.     

Primary perivascular epithelioid cell tumor in the rectum: A case report and review of the literature

Perivascular epithelioid cell tumor (PEComa) is a rare collection of tumors arising in a wide array of anatomic locations. It is characterized by the presence of a peculiar population of myomelanocytic marker-positive perivascular epithelioid cells, and is commonly detected in the uterus. The colorectal area is an uncommon site for primary PEComa. In this study, we describe a 17-year-old patient presenting with a rectal polyp. Histologically, the tumor consisted of sheets of round to polygonal epithelioid cells with clear and granular cytoplasm, and a prominent capillary network. Some of the tumor cells were positive for Fontana-Masson staining. Immunohistochemically, the tumor cells were positive for HMB-45, and were negative for cytokeratin, vimentin, S-100 protein, actin, desmin, EMA, CD34, and c-kit. After finding melanosomes or premelanosomes at the ultrastructural level, the diagnosis of PEComa was made. Although PEComa arising within the intestinal tract is unusual and clinically unexpected, PEComa should be considered in the differential diagnosis of rectal polypoid lesions.     

Oncocytic adrenocortical carcinomas: a pathological and immunohistochemical study of four cases in comparison with conventional adrenocortical carcinomas

Clinicopathological features of four cases of oncocytic adrenocortical carcinomas were studied. All tumors were large, circumscribed tumors with average size and weight of 11.5 cm and 586 g, respectively. The cut surfaces were yellow or brown and tan with areas of hemorrhage, necrosis, fibrosis, myxoid and cystic change. The tumor cells were exclusively oncocytic with a diffuse or compact and solid arrangement. Nuclear atypia was identified but mitosis was rare. Capsular invasion was identified in all tumors and vascular invasion was identified in one tumor. All tumors were immunoreactive for vimentin and inhibins. Immunoreactivity for pancytokeratin, synaptophysin and S-100 protein was variable and focal. All tumors had low proliferative indices, of less than 1%, and were negative for p53 protein. Ultrastructurally, the cytoplasm of tumor cells showed numerous mitochondria in a compact arrangement. Oncocytic adrenocortical carcinomas showed a similar sex ratio, slightly older mean age, similar left predilection, slightly smaller size and lighter weight compared with the conventional carcinomas. We suggest that most oncocytic adrenocortical carcinomas might be low-grade malignancies with less aggressive histological features compared with conventional carcinomas. However, they should be excised completely because of the likelihood of recurrence and metastasis during the follow-up period.     

PLEOMORPHIC ADENOMA WITH A PREDOMINANTLY MYOEPITHELIAL PROLIFERATION OF THE VAGINA

A case of pleomorphic adenoma of the vagina in a 44-year-old woman was described. The tumor was a submucosal mass measuring 3.5 times 2×2 cm and located in the left lateral wall 1.5 cm inside the introitus. Histologically, it was predominantly composed of sheets and strands of spindle-shaped or polygonal cells focally dispersed in the myxoid tissue to form pseudomicrocysts. Ultra-structure demonstrated the basal lamina, desmosomes, variable amounts of filaments of both intermediate and microfilament, and occasionally microvilli in these tumor cells indicating that dominant cells were myoepithelial in nature. With immunohistochemical studies, keratin and cytokeratin were positive, whereas, S-100 protein, glial fibrillary acidic protein, vimentin, secretory component, and lysozyme were negative. The previously published cases were reviewed and compared with the present case.     

Oncocytic differentiation in intrahepatic biliary cystadenocarcinoma.

An intrahepatic biliary cystadenocarcinoma in a 56-yr-old white man was characterized by pronounced oncocytic differentiation. Grossly the tumor was a well-demarcated cyst filled with numerous branching papillary fronds. Most tumor cells had abundant granular, intensely eosinophilic cytoplasm on light microscopic examination and large numbers of densely packed mitochondria by electron microscopy. Mucin-secreting cells were also present. The patient returned 20 mo after resection of the primary tumor with recurrent tumor in the liver and widely disseminated disease throughout the abdominal cavity, and he died 5 mo later. Although less differentiated, the recurrent tumor again contained greatly increased numbers of mitochondria. The partial loss of oncocytic differentiation in the evolution of the present case and the benign nature of purely oncocytic tumors suggest that in the presence of mixed histologic features the potential for tumor progression is primarily determined by the lesser differentiated or nononcocytic component. To the best of our knowledge, oncocytic differentiation has not been previously described in biliary neoplasia.     

Synovial sarcoma: an immunohistochemical and ultrastructural study

Thirty-nine primary synovial sarcomas (15 biphasic, 24 monophasic), and 19 metastatic synovial sarcomas were studied with a battery of antibodies directed to keratin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), vimentin, desmin, muscle-specific actin, smooth muscle actin, S-100 protein, Leu-7, chromogranin A, laminin, collagen IV, Ulex europaeus agglutinin I (UEAI), and the HMB-45 antimelanoma antibody. Twenty-two primary and 18 metastatic synovial sarcomas were also examined by electron microscopy. Epithelial and/or spindle cells in every biphasic tumor, primary and metastatic, reacted for keratin and EMA, but only six primary tumors (five biphasic and one monophasic) showed weak reactivity for CEA which, in the biphasic tumors, was confined to the epithelial component. Of the monophasic tumors, 15 primary (63%) and four metastatic (25%) stained for keratin, whereas seven primary (29%) and two metastatic (13%) tumors reacted for EMA. Only one primary monophasic synovial sarcoma stained for CEA. Tumors that stained for EMA or CEA also stained for keratin which is, therefore, the most useful epithelial marker. Immunostaining for epithelial markers, UEAI, collagen IV, and laminin serves to delineate the epithelial component when it is obscure in routine sections. Electron microscopy facilitates the diagnosis when epithelial markers are not expressed and aids in separating monophasic synovial sarcomas from other sarcomas that they resemble by light microscopy.     

Adenoma of the non-pigmented ciliary epithelium: A rare intraocular tumor with unusual immunohistochemical findings

A case of adenoma of the non-pigmented ciliary epithelium with smooth muscle differentiation is reported. This uncommon ocular tumor affected a 36-year-old woman, and had caused decreased visual acuity and a total cataract. Ultrasound biomicroscopy disclosed an associated persistent hyperplasic primary vitreous (PHPV). Sectoral cyclectomy with removal of the mass and intracapsular cataract extraction were performed. The tumor was diffusely positive for vimentin, smooth muscle actin, NSE, and S-100, focally for CD68 and Melan-A, and was negative for desmin, EMA, HMB-45, and CD99. Occasional cells reacted for cytokeratin. The proliferation index, as assessed by Ki-67, was below 10%. The overlying non-neoplastic ciliary epithelium was positive for vimentin, NSE, and S-100.     

"Proximal type" epithelioid sarcoma of the vulva: differential diagnosis with other extrarenal rhabdoid tumors

Proximal type epithelioid sarcoma is a rare neoplasia in which morphological findings are characterized by nodular proliferation of epithelioid cells with focal rhabdoid features. It shares some histological features with other neoplasias and this gives an account of several differential diagnosis with other extrarenal rhabdoid tumors. Immunohistochemical and ultrastructural analysis are important in defining this entity: vimentin, cytokeratin, EMA and often CD34 expression of tumoral cells, moreover ultrastructurally evidence of large paranuclear whorls of intermediate filaments, are requested for diagnosis. A correct diagnostic framing is necessary because of the aggressive clinical behaviour of this tumor, that has a tendency to early spreading. We describe a case of vulvar proximal type epithelioid sarcoma in a 34 years old woman.