Abstract
Malignant fibrous histiocytoma (MFH), the malignant counterpart of the so-called fibrohistiocytic tumors, was first described in 1963 and is generally accepted as one of the most common types of soft tissue sarcoma in the extremities of elderly patients (Weiss and Enzinger 1978; Gibbs et al. 2001). The concept and classification of MFH have changed over the past five decades. With recent advances in immunohistochemistry, cytogenetic, and molecular genetic studies, many tumors labeled ‘MFH’ could be subclassified as lineage-specific sarcoma after reassessment and close scrutiny. The World Health Organization (WHO) significantly reorganized the nomenclature of MFH in 2002. The term ‘MFH’ was removed, and the lesions are now included in the quite separate and new category of undifferentiated/unclassified sarcomas. The myxoid variant of MFH was renamed ‘myxofibrosarcoma’ and moved into the fibroblastic/myofibroblastic tumor section. These lesions show no definable line of differentiation using currently available technologies. Dedifferentiated types of specific sarcomas are not included in this category. Such undifferentiated tumors may have spindle cell, pleomorphic, round cell or epithelioid cytomorphologies. A significant subset of radiation-associated sarcomas is included in this category (Rosenberg 2013; Fletcher 2014; Goldblum 2014; Doyle 2014).
Published Version
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