HISTOGENETIC RELATIONS BETWEEN GIANT-CELL FIBROBLASTOMA AND DERMATOFIBROSARCOMA PROTUBERANS - CD34 STAINING SHOWING THE SPECTRUM AND A SIMULATOR

The authors describe three lesions that provide further evidence for a close, possibly histogenetic relation between giant cell fibroblastom a and dermatofibrosarcoma protuberans. The first case involves a derma tofibrosarcoma protuberans that contained a single giant cell fibrobla stoma-like focus of multinucleate giant cells. A second tumor, a giant cell fibroblastoma, recurred 6 years later as a dermatofibrosarcoma p rotuberans. In the third lesion, there was a juxtaposition and co-ming ling of dermatofibrosarcoma protuberans and giant cell fibroblastoma w ithin the same primary lesion. In all cases, both the giant cell fibro blastoma areas and dermatofibrosarcoma protuberans areas stained posit ively with CD34. A fourth case, a dermatofibrosarcoma protuberans infi ltrated skeletal muscle, creating giant cell fibroblastoma-like giant cell mimics-a result of skeletal muscle degeneration or atrophy with n uclear conglomeration. The latter giant cells failed to express CD34 b ut did show immunoreactivity with desmin. These findings support the c oncept that giant cell fibroblastoma and dermatofibrosarcoma protubera ns probably represent a histologic spectrum of a single CD34 positive (perhaps, dermal dendrocytic) neoplasm, a conclusion supported by a re cently cloned t(7;22) breakpoint demonstrated in both neoplasms.