[Fibrohistiocytic skin tumors]

Abstract

The fibrohistiocytic tumors of the skin are a heterogeneous group of dermal/subcutaneous mesenchymal neoplasms which show fibroblastic, myofibroblastic and histiocytic (macrophage-like) differentiation, often one beside the other in the same tumor. "Fibrohistiocytic" means in this context the morphologic similarity of the cells with fibroblasts and histiocytes. The WHO classification of 2005 includes the following entities as fibrohistiocytic tumors of the skin: BENIGN: 1. Fibrous histiocytoma (FH)/(synonymous: Dermatofibroma. Variants of FH: 1a. cellular fibrous histiocytoma, 1b. atypical (pseudosarcomatous) fibrous histiocytoma, 1c. aneurysmatic fibrous histiocytoma, 1d. epithelioid fibrous histiocytoma; 2. dermatomyofibroma; 3. (juvenile) xanthogranuloma. INTERMEDIATE: 4. plexiform fibrohistiocytic tumor; 5. dermatofibrosarcoma protuberans; 6. atypical Fibroxanthoma. MALIGNANT: 7. malignant fibrous histiocytoma. All these entities are reviewed in this paper with particular attention devoted to differential diagnostic considerations.