Primary meningeal sarcomas with leiomyoblastic differentiation: a proposal for a new subtype of primary meningeal sarcomas.

Two cases of primary meningeal sarcoma with leiomyoblastic differentiation are presented. In case no. 1, the tumor showed anaplastic spindle cell tumor components intermingled with anaplastic meningothelial components. Meningothelial tumor cells gradually became transformed into spindle tumor cells. Spindle tumor cells reacted with antisera to muscle actin (HHF-35) and alpha-smooth muscle actin. However, unchanged meningothelial tumor cells did not react with the antisera to HHF-35 and alpha-smooth muscle actin. Electron microscopy showed condensations of cytoplasmic fibers and pinocytotic vesicles in spindle tumor cells similar to those seen in smooth muscle cells. In case no. 2, the tumor cells consisted predominantly of sheets of round or polygonal cells as seen in an epithelioid leiomyosarcoma. The neoplastic cells had frequent nuclear inclusions, such as those seen in meningiomas. Immunohistochemically, the tumor cells reacted with antisera to desmin and to HHF-35. Electron microscopy showed a basal lamina around the cytoplasm of tumor cells. Intranuclear inclusions with various cytoplasmic organelles were frequently observed in the tumor cells, as in meningiomas. Interdigitating cytoplasmic processes and intercellular junctional complexes, however, were not found in the tumor cells. Two possible hypotheses explain the occurrence of leiomyoblastic characteristics of these cases. In case no. 1, leiomyoblastic cells originated from meningothelial cells with the advancement of meningothelial anaplasia. In case no. 2, pluripotential mesenchymal cells in the meninges differentiated into meningothelial and smooth-muscle cell lines at the time of tumor growth. With consideration of previous publications on primary meningeal sarcoma, these cases are the first reported primary meningeal sarcoma with leiomyoblastic and meningothelial differentiation.

Leiomioblastoma primario de epiplón. Aportación de un caso y revisión bibliográfica / Primary leiomyoblastoma of the omentum. A case report and a review of the literature

Presentamos un caso de leiomioblastoma primario de epiplón intervernido en nuestro servicio. Estos tumores son neoplasias que derivan del músculo liso y afectan fundamentalmente al estómago. La aparición como tumores primarios de epiplón es extremadamente rara. En la bibliografía médica mundial solamente se han publicado 14 casos. Aportamos un nuevo caso y realizamos una revisión bibliográfica discutiendo su clínica, diagnóstico, criterios histológicos de malignidad y tratamiento (AU)

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Clear-cell epithelioid leiomyoma of the round ligament.

A case of clear-cell epithelioid leiomyoma of the round ligament in a 69-year-old woman is described. The neoplasm presented as a firm left inguinal mass. A preoperative computed tomography (CT) scan demonstrated an enhancing lesion extending extra-abdominally from the region of the external inguinal ring. The surgical resection specimen was tan-white, well-circumscribed, and measured 5.8 cm in maximum dimension. Microscopic examination revealed a well-demarcated neoplasm comprised of polygonal cells with abundant clear cytoplasm arranged in clusters and single files with abundant intervening hyalinized stroma. There was minimal nuclear atypia and mitotic figures were rare. Periodic acid-Schiff with diastase demonstrated intracytoplasmic glycogen. Immunohistochemical stains for pan-actin, smooth muscle actin, desmin, bcl-2, and vimentin were positive in the tumor cells, whereas stains for CD34, carcinoembryonic antigen, cytokeratin, epithelial membrane antigen, S100 protein, and neurofilaments were negative. Electron microscopy demonstrated features of smooth muscle differentiation including longitudinally oriented fine filaments with focal condensations, pinocytotic activity, and subplasmalemmal densities. This case illustrates the ubiquitous distribution of epithelioid smooth muscle neoplasms and highlights the potential pitfalls for diagnosis when they occur in an unusual location.