The histiocytic nature of dermatofibrosarcoma protuberans. Tissue culture and electron microscopic study.

Specimens from four cases of dermatofibrosarcoma protuberans when explanted in vitro exhibited a typical ameboid outgrowth, confirming the histiocytic nature of these tumors. The cultures displayed the same evolution from macrophages to fibroblast-like cells observed previously in cultures of other types of histiocytomas. Electron microscopic study of the cultures confirmed the light microscopic findings and suggested that the fibroblast-like cells were histiocytes with some secondarily acquired fibroblastic features. The possibility that neoplastic histiocytes may transform into true fibroblasts was deemed unlikely, but could not be excluded.