The contribution of electron microscopy to the characterization of soft tissue fibrosarcomas

In recent years, with the application of immunohistochemical and cytogenetic methods, numerous lesions formerly diagnosed as fibrosarcoma were reclassified as other malignant soft tissue tumors, and therefore conventional fibrosarcoma has largely become a diagnosis of exclusion. On the other hand, several new entities belonging to the group of fibrosarcomas have been characterized, including low-grade fibromyxoid sarcoma / hyalinizing spindle cell tumor with giant rosettes, sclerosing epithelioid fibrosarcoma, acral myxoinflammatory fibroblastic sarcoma, and the epithelioid variant of myxofibrosarcoma. Electron microscopy has contributed to the identification of the fibroblastic phenotype in these fibrosarcoma variants and still retains a central role in the differential diagnosis of these soft tissue sarcomas, thus helping to render specific diagnoses and to broaden the spectrum of fibrosarcoma variants.