"Proximal-type" epithelioid sarcoma, a distinctive aggressive neoplasm showing rhabdoid features. Clinicopathologic, immunohistochemical, and ultrastructural study of a series

Epithelioid sarcoma of the penis: report of an unusual case and review of the literature

Epithelioid sarcoma is a rare, slowly growing soft tissue tumor that uncommonly involves the penis, with only 11 previously reported cases. We present a case of penile epithelioid sarcoma in a 39-year-old man that mimicked Peyronie's disease, which was diagnosed 13 years following initial presentation. Preoperative magnetic resonance imaging showed multiple peripherally enhancing low signal intensity nodules involving the corpora cavernosa bilaterally. Following penectomy, histologic examination showed the typical features of epithelioid sarcoma, with a prominent pseudogranulomatous pattern. Immunohistochemically, the neoplastic cells demonstrated strong and diffuse staining for cytokeratins (AE1/AE3 and CAM 5.2), vimentin, epithelial membrane antigen, and CD34. Stains for S-100 protein, desmin, smooth muscle actin, and CD31 were negative. Electron microscopy demonstrated abundant intracytoplasmic intermediate filaments, scattered tonofilaments, and interdigitating filopodia. The present study is the first to describe magnetic resonance imaging and comprehensive immunohistochemical findings in penile epithelioid sarcoma. The majority of cases reported in the literature have demonstrated features similar to those typically found in epithelioid sarcoma involving the distal extremities. Consideration of epithelioid sarcoma in the differential diagnosis of a penile nodule or obstructive urinary symptoms may lead to early diagnosis and treatment.

Extraskeletal Myxoid Chondrosarcoma with Rhabdoid Features, with Special Reference to Its Aggressive Behavior

The presence of rhabdoid cells has been reported in various types of malignant neoplasms. Thirty-six cases of extraskeletal myxoid chondrosarcoma (EMC) were reviewed, and three of them revealed rhabdoid features. These cases contained cells having prominent eosinophilic globular cytoplasm, but were otherwise typical of EMC. Immunohistochemically, cytokeratin (CAM 5.2) was positive in three of 20 cases (15%), including two of the three with rhabdoid features. The rhabdoid cells were also immunostained with vimentin. The 5-year survival rate in the 26 cases with follow-up information was 73%, and the 10-year survival rate was 63%. The cases with rhabdoid features had a significantly poorer prognosis (p=0.0271). This study suggests that presence of rhabdoid features is a predictor of aggressive behavior in EMC, as it was shown to be in other mesenchymal neoplasms. Int J Surg Pathol 8(2):145-152, 2000

Epithelioid variant of malignant peripheral nerve sheath tumor (malignant schwannoma) of the urinary bladder

Sarcoma represents less than 2% of all neoplasms diagnosed or recognized in effusions. Epithelioid peripheral nerve sheath tumor is a rare tumor that is difficult to differentiate from other epithelioid tumors without the use of ancillary studies. A 39-year-old paraplegic man presented with hematuria and a bladder mass that extended to involve the pelvic peritoneum. Light microscopy using hematoxylin-eosin, Papanicolaou, and immunohistochemical stains as well as transmission electron microscopy showed features of epithelioid malignant peripheral nerve sheath tumor with rhabdoid features and an accompanying eosinophilic infiltrate. Cytologic smears confirmed the similarities between the primary tumor in the bladder and the cells in the pelvic fluid and excluded the possibility of reactive changes related to postsurgical radiation. Ancillary studies were critical in narrowing the differential diagnoses and reaching the final conclusion.

High-grade extraskeletal myxoid chondrosarcoma: a high-grade epithelioid malignancy

AIMS

Extraskeletal myxoid chondrosarcoma is typically a low-to-intermediate grade sarcoma that is associated with a prolonged clinical course. High-grade forms are rare and not well characterized. In this series we report the clinicopathological, immunohistochemical and ultrastructural findings in four cases of high-grade extraskeletal myxoid chondrosarcoma.

METHODS AND RESULTS

The patients were three men and one woman (ages 34-73 years) with tumours located in the thigh (two cases), paraspinal soft tissue and perineum. Three patients had metastases, one at 12 weeks, one at 10 months, and one at presentation of recurrent tumour. In the latter case the original tumour was low grade and became high grade when it recurred 3.5 years later. All three patients died of disease. One patient was lost to follow-up. The most striking histological feature in all four tumours was the presence of numerous large epithelioid cells. These cells were arranged in cords within myxoid matrix and in sheets devoid of matrix. Two tumours had areas of conventional extraskeletal myxoid chondrosarcoma intermixed with the high-grade areas. One tumour showed transition to high-grade spindle cell sarcoma. One tumour had cells with rhabdoid features. Immunohistochemically, two tumours focally expressed S100 protein, and one focally expressed EMA. All were negative with cytokeratin, desmin, smooth muscle actin, HMB45, CD31 and CD34. Ultrastructural features in three cases were compatible with chondrosarcoma; one tumour had aggregates of microtubules within rough endoplasmic reticulum, a characteristic feature of this tumour.

CONCLUSIONS

High-grade extraskeletal myxoid chondrosaroma is a rare and aggressive soft tissue sarcoma, and should be included in the differential diagnosis of other epithelioid malignancies.

Epitheloid sarcoma of the penis

We report a case representing the clinical as well as histopathologic features of epitheloid sarcoma. Both a clinical review and the results of definitive treatment together with the follow-up data are presented.

Epithelioid sarcoma: an immunohistochemical analysis of 112 classical and variant cases and a discussion of the differential diagnosis

Epithelioid sarcoma (ES) is a distinctive soft tissue neoplasm with a predilection for the distal extremities of young adults. This tumor typically contains nodular aggregates of epithelioid and spindle cells with zonal necrosis. The neoplastic cells are generally reported to coexpress keratin and vimentin and are often stated to be positive for CD34. However, there is no large series with extensive immunohistochemical data, there are few data with regard to expression of different keratin subtypes, and there are no large series discussing the epithelioid sarcoma subtypes. In the current study, we immunohistochemically evaluated 88 typical and 24 variant (8 angiomatoid, 9 large cell/rhabdoid, and 7 "fibroma-like") ESs. Nearly all ESs with typical histology (94%) were positive for keratin 8 (K8), whereas 72% were positive for K19, 48% for intermediate- and high-molecular-weight keratins (34betaEH12), and 22% for K7; reactivity with the latter two antibodies was usually seen in only a minority of tumor cells. Vimentin reactivity was present in all cases, EMA in 96% of cases and muscle-specific actin and CD34 were noted in 41% and 52% of the cases, respectively. A few ESs (7%) showed focal cytoplasmic CD31 reactivity, but none exhibited a distinctive membrane staining pattern, and examples tested for FVIIIRAg were negative. The angiomatoid, fibroma-like, and large cell-rhabdoid ES variants had immunohistochemical profiles similar to the classic cases, supporting a common pathogenesis. Although not consistently expressed in ES, the presence of CD34 is helpful in distinguishing this entity from primary and metastatic carcinomas and other sarcomas such as malignant rhabdoid tumor.

Malignant myoepithelioma of the vulva resembling a rhabdoid tumour

AIMS

We report an example of malignant myoepithelioma of the vulva, which has not been hitherto described. We discuss the differential diagnosis and briefly review the literature.

METHODS AND RESULTS

The lesion was found in an 81-year-old woman as an indolent 40 mm tumour. The neoplastic cells showed a myoid, spindled, epithelioid and plasmacytoid phenotype. Hyalinization of extracellular material and myxoid changes were present. There was a partly solid and microcystic pattern and a tight cohesiveness of cells was lacking. The circumscribed multinodular tumour somewhat resembled an extrarenal rhabdoid tumour, having large tumour cells with prominent nucleoli and large amounts of acidophilic cytoplasm. Immunohistochemically, the tumour cells were immunoreactive for cytokeratin, vimentin, muscle-specific actin, alpha-smooth muscle actin, and S100 protein, but not for desmin, epithelial membrane antigen, factor VIII-related antigen, CD34 and CD31.

CONCLUSIONS

The histological and cytomorphological appearance of the tumour well as the immunohistochemical findings suggest the diagnosis of malignant myoepithelioma, possibly derived from minor vestibulary glands or ectopic breast tissue. Differential diagnoses are, in particular, extrarenal rhabdoid tumour and 'proximal type' epithelioid sarcoma. Differentiation is important, because the tumours show a different behaviour and prognosis.

Immunohistochemistry in diagnostic dermatopathology

This article briefly reviews many immunohistochemical stains that have been in use for years, emphasizing their diagnostic use and potential pitfalls. Several newer immunostains are described in a more comprehensive fashion, including brief summaries from recently published studies.

Epithelioid sarcoma of the vulva

We report a case of a 23-year-old woman diagnosed as having an epithelioid sarcoma of the vulva. She was treated by a clitoris-sparing hemivulvectomy and lymph node sampling of the ipsilateral groin. Vulvar reconstruction was performed with a rectus abdominis myocutaneous flap. Four years after the operation there is no evidence of disease and the patient has a normal sex life. The English literature on this subject is reviewed with special attention to the biological behavior and therapeutic approach.

Proximal-type epithelioid sarcoma in the pelvic soft tissues

A case of proximal-type epithelioid sarcoma arising in the pelvic soft tissues of a 46-year-old man is presented. The tumor showed a predominantly epithelioid component with rhabdoid features, cord-like arrangement, small nests, abundant eosinophilic cytoplasm containing intracytoplasmic, paranuclear, hyaline-like globules, large vesicular nuclei, and prominent nucleoli. There were foci with alveolar arrangement and a spindle-cell proliferation. The tumor cells were positive for cytokeratin CAM5.2, vimentin, epithelial membrane antigen, and CD34. Flow cytometry showed a diploid DNA content with high S-phase fraction. The patient had pelvic lymph-node metastases. He died of the disease 5 months after diagnosis. It is important to include proximal-type epithelioid sarcoma in the differential diagnosis of pelvic tumors.

Poorly differentiated synovial sarcoma: an analysis of clinical, pathologic, and molecular genetic features

Poorly differentiated synovial sarcoma is a variant of synovial sarcoma in which the tumor cells lack the bland spindle cell appearance of the usual type monophasic synovial sarcoma. Although poorly differentiated synovial sarcoma has been recognized as an entity for many years, no series addressing the clinicopathologic features of this variant have appeared. We describe the histologic, immunohistologic, and molecular findings of a series of 20 poorly differentiated synovial sarcomas. Three types of poorly differentiated synovial sarcoma can be recognized: a large cell epithelioid variant, a small cell variant, and a high-grade spindle cell variant. Epithelial membrane antigen reactivity was seen in 95% of cases, and reactivity for cytokeratin was seen in 42%. The S100 antigen was expressed in 63% of cases. Electron microscopic findings in poorly differentiated synovial sarcoma parallel those found in usual type synovial sarcoma. In 10 cases, material was available for molecular studies; 9 of 10 cases showed the presence of t(X;18) or the associated fusion gene product. These data indicate that poorly differentiated synovial sarcoma is a lesion that shares immunologic, ultrastructural, and molecular characteristics with the usual synovial sarcoma. Follow-up data were available in 16 patients with a mean follow-up of 39 months. Eight patients died with a mean survival time of 33 months. Poorly differentiated synovial sarcoma is a variant of synovial sarcoma that may be associated with a poor prognosis.

Synovial sarcoma

Synovial sarcoma is a rare soft tissue tumor of children and adults that is unrelated to synovium and can occur in almost any part of the body. The familiar biphasic synovial sarcoma has discernible glandular or solid epithelial structures, and monophasic forms have characteristic ovoid or spindle cells with only immunohistochemical or ultrastructural evidence of epithelial differentiation. There are several morphologic patterns, including myxoid and hemangiopericytic, and behaviorally distinct calcifying, ossifying, and poorly differentiated subtypes can be recognized. Most synovial sarcomas are immunoreactive for cytokeratin, epithelial membrane antigen, and bc12 protein, and negative for CD34, and many express S100 protein and CD99 (MIC2). Nearly all synovial sarcomas have a specific t(x;18) (p11.2;q11.2) chromosomal abnormality, resulting in fusion of either of two variants of the SSX gene with the SYT gene; the genetic features may relate to morphology and outcome. The differential diagnosis can include a wide range of spindled, polygonal, or round cell sarcomas. Clinically, there have been marked recent improvements in local control of disease and lesser ones in management of metastases. The pathology, differential diagnosis, and behavior of this unique tumor are reviewed.

"Rhabdoid" meningioma: an aggressive variant

It is has been suggested that rhabdoid morphology is associated with a poor prognosis, regardless of tumor histogenesis. We report a series of 15 meningiomas with rhabdoid features. Nine patients had undergone multiple resections. In six, the rhabdoid component was histologically apparent only in recurrences. Rhabdoid morphology was defined as sheets of loosely cohesive cells with eccentric nuclei and hyaline, paranuclear inclusions. Ultrastructurally, the latter consisted of whorls of intermediate filaments often entrapping lysosomes or other organelles. Meningothelial features included whorl formation and nuclear pseudoinclusions, immunohistochemical coexpression of vimentin and epithelial membrane antigen, and the ultrastructural finding of interdigitating cell membranes and intercellular junctions. At the histologic level, a conventional meningioma component was noted in most tumors; only four lesions were entirely rhabdoid. Histologic malignancy (brain invasion or anaplasia) was observed in nine cases, another two tumors being considered malignant on the basis of extracranial metastasis. In the majority, increased cell proliferation was evidenced by a high mitotic rate or MIB-1 LI. At last follow-up, 13 patients (87%) had experienced at least one recurrence and 8 (53%) were dead of disease. Median time to death was 5.8 years after initial surgery and 3.1 years after the first appearance of rhabdoid morphology. Our findings corroborate those from a smaller series recently reported by Kepes et al. on the same entity (Kepes JJ, Moral LA, Wilkinson SB, Abdullah A, Llena JF. Rhabdoid transformation of tumor cells in meningiomas: A histologic indication of increased proliferative activity. Report of four cases. Am J Surg Pathol 1998;22:231-8). They further suggest that rhabdoid meningiomas are highly aggressive tumors and that the rhabdoid phenotype represents a marker of malignant transformation in meningiomas.

Primary liposarcoma of the stomach: a case report and a review of the literature

Primary liposarcoma of the stomach is rare and only seven cases have been described in the English literature. Here we report the eighth case, which occurred in a 68-year-old woman who presented with repeated tarry stools and hematemesis. Endoscopic examination revealed a large ulcerated submucosal mass at the gastric angle. The patient was treated by total gastrectomy. On microscopic examination, the tumor showed the features of a well differentiated sclerosing liposarcoma. Immunohistochemically, many spindle to stellate tumor cells were diffusely positive for vimentin and CD34. Positivity for S-100 protein was found in the adipocytic component, including lipoblasts, in addition to some spindle-shaped tumor cells. On ultrastructural examination, the spindle to stellate cells had features characteristic of fibroblasts. No recurrence or metastasis was seen during 13 months. Liposarcoma of the stomach has to be considered in the differential diagnosis with other submucosal lesions, such as gastric lipoma and gastrointestinal stromal tumor.

Rhabdoid transformation of tumor cells in meningiomas: a histologic indication of increased proliferative activity: report of four cases

Four cases of meningeal tumors in adults (ages ranging from 28 to 84 years) are presented. All had the typical gross appearance of meningiomas at operation. In three tumors, areas of meningothelial or fibroblastic meningiomas showed transition to cell groups of the rhabdoid type. In the fourth case only rhabdoid cells were encountered, possibly representing a total "take-over" of a meningioma by rhabdoid elements. In the three cases with mixed pattern, the rhabdoid cells showed more anaplasia and atypism than the conventional meningiomatous elements. In case 3 this was expressed by very high MIB-1 positivity in the rhabdoid cells and absence of same in the fibroblastic meningiomatous elements. These cases (the first three with certainty, the fourth with a strong likelihood) indicate that the phenotypic changes to cells with "rhabdoid" morphology may involve meningiomas and that such change is associated with aggressive biologic and clinical behavior of the tumors showing this type of alteration.