Malignant spindle cell tumor of the pericardium. Evidence of sarcomatous mesothelioma with aberrant antigen expression

A case of malignant spindle cell tumor occurring in the pericardium is presented. The tumor arose from the pericardium of a 51-year-old Japanese woman with no history of exposure to asbestos. The tumor extended into the pericardial and left pleural cavities. The primary and metastatic tumors consisted of fusiform cells with frequent mitoses. Ultrastructurally, the tumor cells possessed a discontinuous external lamina, cytoplasmic processes, microfilaments and desmosomal intercellular junctions. Immunohistochemical examination showed that most tumor cells were positive for Leu 7, and several for S-100 and glial fibrillary acidic protein. Unexpectedly, most of the tumor cells also expressed keratin. These findings favor a diagnosis of sarcomatous mesothelioma with aberrant antigenic expression or heterogeneous differentiation of neoplastic cells.     

Malignant peripheral nerve sheath tumor of small round cell type with pleomorphic spindle cell sarcomatous areas

An unusual case of malignant peripheral nerve sheath tumor (MPNST) arising in the posterior mediastinum of a 59-year-old man is reported. Histopathologically, the tumor showed an admixture of a dense proliferation of small round cells resembling a primitive neuroectodermal tumor (PNET) and a pleomorphic spindle cell sarcomatous area. Abortive rosettes, primitive neural tube-like structures, and a few glandular structures were found in the small round cell area. Small round cells were immunoreactive for neural cell adhesion molecule and synaptophysin, but were not immunoreactive for MIC2 and neuron-specific enolase. Pleomorphic spindle cells were occasionally arranged in a storiform pattern and were diffusely immunoreactive for S-100 protein. The MPNST of small round cell type is distinguishable from PNET by its negative immunoreactivity for MIC2, and the present tumor is assumed to be derived from primitive neuroectodermal cells in the peripheral nerve capable of bidirectional (neuron and Schwann cell) differentiation.     

Malignant mediastinal germ cell tumor with pure hepatoid differentiation

We describe a germ cell tumor of anterior mediastinal origin, with pure hepatoid differentiation and elevated serum AFP in a 41-year-old man. This is the first report of such a neoplasm analyzed by conventional stains and immunohistochemistry. Hepatocellular differentiation was proved by immunoreactivity with HepPar-1 and alpha-fetoproein (AFP), membranous expression of carcinoembryonic antigen (CEA-poly) in a canalicuar pattern, and focal expression of cytokeratin 19 in abortive ductular structures. Our investigation shows that mediastinal germ cell tumors with hepatoid components typically arise in middle-aged men; they are of pure hepatoid differentiation, as demonstrated here, or exclusively associated with yolk sac structures.     

Malignant eccrine spiradenoma with carcinomatous and sarcomatous elements.

A case of a 60 year old man with malignant eccrine spiradenoma involving the perineum is described. Areas of typical eccrine spiradenoma were admixed with carcinomatous and sarcomatous elements. Immunohistochemical and ultrastructural analysis revealed no evidence of epithelial differentiation in the sarcomatous areas. The tumour qualified for the designation carcinosarcoma arising in eccrine spiradenoma. The clinical course was aggressive with rapid development of nodal and pulmonary metastases.     

Malignant granular cell tumor.

We report a case of malignant granular cell tumor of the chest wall that recurred in the right breast with axillary lymph node metastases. The recurrent tumor clinically and grossly mimicked a breast carcinoma. Electron microscopy and immunohistochemical techniques were used to confirm the cytologic and histologic diagnosis of granular cell tumor. The importance of true metastases in the diagnosis of malignant granular cell tumor and their differential diagnosis are discussed.     

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.     

Malignant peripheral nerve sheath tumor with divergent differentiation

Right posterior thigh malignant peripheral nerve sheath tumor with malignant glandular and rhabdomyoblastic components was diagnosed in a 24-year-old African American man. Malignant glands and rhabdomyoblastic cells were admixed with the spindle cells. Immunohistochemistry demonstrated spindle cells positive for S100 and vimentin; the glandular component was positive for chromogranin, and rare cells were positive for CK20 but negative for CK7. Rhabdomyoblastic cells were positive for muscle-specific actin and desmin. A single pulmonary metastasis occurred 5 months after surgical resection of the tumor. Death occurred 1 month later and was probably due to a pulmonary embolus.     

Malignant mesothelioma--a connective tissue tumor with proteoglycan-dependent differentiation

Malignant mesothelioma (MM) is a connective tissue tumor with partial epithelioid differentiation. The pattern of proteoglycan (PG) expression by epithelioid and fibroblast-like (sarcomatoid) MM cells differ; cell surface PGs being more abundant in the former phenotype and matrix PGs in the latter. The differentiation as well as much of the malignant nature of these tumors is dependent on the expression of surface PGs. The syndecans, however, also translocate to the nucleus for an as yet unknown function.     

Metastatic Leydig cell tumor with sarcomatoid differentiation.

Leydig cell tumors of the testis are uncommon. Only about 10% of cases have a malignant course. It has been stated that the only definite criterion for malignancy is presence of metastasis. We present a 47-year-old patient with metastatic Leydig cell tumor 17 years after initial diagnosis, to our knowledge the longest reported interval between diagnosis and the development of metastasis. The primary tumor did not exhibit convincing features of malignancy. The initial metastasis in the right perirenal fat tissue showed a biphasic tumor with sarcomatoid differentiation not described previously in a metastatic Leydig cell tumor.     

Malignant glial tumor with skeletal muscle differentiation. Description of a case

A case of CNS gliomyosarcoma, in a 71-year-old female with skeletal muscle differentiation is presented. The tumor was composed by two cell types: one showed features typical of glial cells, the other was constituted by elements having immunohistochemical positivity with desmin, sarcomeric actin, myoglobin and myogenin antisera. It is postulated an origin from a cell capable of dual differentiation.     

Malignant granular cell tumor

A case of a granular cell tumor with a malignant behavior is described. Several repeated biopsy specimens, a resection specimen, and the metastatic lesions were compared with one another. Consecutive specimens showed increasing atypia. Electron microscopy of the metastatic lesions confirmed the granular cell nature of the tumor. The historic aspects of histogenesis are briefly discussed. The findings agree with a presently accepted origin from a primitive mesenchymal cell.     

Malignant solitary fibrous tumor of the pleura with liposarcomatous differentiation

Pleural solitary fibrous tumors (SFTs) are uncommon tumors. Although these tumors have been well characterized, malignant pleural SFTs with liposarcomatous differentiation have not been reported. We report an unusual malignant pleural SFT intermixed with foci of well-differentiated liposarcoma. The patient was a 66-year-old, white man with a large, solid right pleural mass that measured 13.5 x 10.3 x 8.5 cm. The tumor was composed of spindle-shaped and plump cells embedded in dense collagenous stroma. The tumor cells were arranged in interlacing fascicles or in a patternless pattern. Marked nuclear atypia, a high mitotic rate (21 mitoses per 10 high-power fields), and areas of prominent necrosis were evident. In addition, numerous adipocytes mixed with typical lipoblasts were seen scattered throughout portions of the tumor. Immunohistochemistry revealed the tumor cells were strongly positive for CD34 and vimentin and negative for cytokeratin, desmin, smooth muscle actin (IA4), and S100. To the best of our knowledge, this case represents the first example of a malignant SFT with liposarcomatous differentiation.     

Malignant phyllodes tumor of the breast with predominant chondrosarcomatous differentiation

Malignant phyllodes tumor of the breast is a rare biphasic neoplasm, the stromal component of which may show homologous and heterologous sarcomatous elements. We present a case of a histologically malignant phyllodes tumor with sarcomatous overgrowth, affecting a 37-year-old woman in whom a chondrosarcomatous component constituted over 80% of the tumor volume. A malignant phyllodes tumor displaying a predominant chondrosarcomatous component is indeed rare, and the differential diagnosis could well affect the therapeutic approach, mainly with regard to metaplastic carcinoma and primary chondrosarcoma of the mammary gland. Thus, it is important to sample the tumor thoroughly to detect the presence of any area of typical phyllodes tumor, which could be very small. Immunohistochemical stains also should be performed so as to exclude a malignant epithelial component. After the final morphological diagnosis, our patient underwent a complete mastectomy without axillary disection. One year later, no local recurrence or metastasis was apparent.     

Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation (malignant triton tumor)

Malignant peripheral nerve sheath tumors arise from Schwann cells or within existing neurofibromas and have a strong association with type 1 neurofibromatosis. These tumors are histologically diverse and may contain malignant areas of divergent mesenchymal differentiation, the most common of which is skeletal muscle (rhabdomyosarcoma). Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation is also known as malignant triton tumor. Malignant triton tumor has a worse prognosis than classic malignant peripheral nerve sheath tumor does, and the correct diagnosis requires attention to the clinical history and knowledge of the complexities regarding its differential diagnosis. In this review we discuss the clinical, histopathological, immunohistochemical, and prognostic features of this rare neoplasm.     

Malignant rhabdoid tumor of the liver. Evidence for epithelial differentiation

Malignant rhabdoid tumors most commonly occur in the kidney. Rarely does this tumor arise in extrarenal sites; a single documented primary hepatic tumor has been described. We describe two patients who had malignant tumors arising in the liver. These tumors demonstrated cytologic, histologic, and ultrastructural features typical of malignant rhabdoid tumor. By immunohistochemistry, the tumor cells from both patients expressed the epithelial membrane antigen, cytokeratin, and vimentin and cells from one patient contained alpha 1-antitrypsin. Neither patient had evidence of renal involvement at autopsy. Thus, we demonstrate that this rapidly fatal tumor contains cells showing features of epithelial differentiation, and that it may occur as a primary hepatic tumor.     

Malignant granular cell tumor with unusual histological features

Malignant granular cell tumor, although uncommon, should be differentiated from a number of granular cell-containing tumors. Reported herein is a distinctive variant of malignant granular cell tumor, clinically presenting as a rapidly enlarging scrotal mass, in which some areas morphologically displayed features indistinguishable from Kaposi sarcoma. Cells in areas simulating Kaposi sarcoma were immunohistochemically the same as typical granular cells in other portions of the tumor. The recognition of this pattern is important because it may predominate and overshadow the original nature of tumor.