Dermatofibrosarcoma protuberans (DFSP) is a rare fibroblastic skin
tumor of intermediate
malignancy. Its pathogenesis has not yet been fully clarified. Recent basic genetic research has shown
chromosomal translocations, generally termed "
ring chromosomes", in DFSP. These arise from a fusion of chromosome regions 17q22 and 22q13, the gene loci which code the alpha chain of
type I collagen. The diagnosis is made histologically. Differentiation from atypical
dermatofibroma and dermatomyofibroma, as well as from
malignant fibrous histiocytoma, whose prognosis is usually much less favorable, can be improved by immunostaining for CD 34 and
Factor XIIIa. The extent of the
tumors can be estimated by CT and more precisely with MRI. All these techniques fail to detect the fine
tumor fascicles extending into the adjacent connective tissue and fat. Surgery is the
therapy of choice for DFSP. The locally infiltrative growth pattern features clinically inapparent extensions which often extend for long distances in a horizontal direction. These
tumor extensions are best detected by uninterrupted histological check of all margins, including the base (3-D-histology), with
paraffin sections. Re-excision of
tumor-positive areas until
tumor-free margins are obtained ("histographic surgery") insures a high cure rate (97%) while preserving normal tissue.