Giant cell fibroblastoma. A juvenile form of dermatofibrosarcoma protuberans.

A clinicopathologic analysis of 28 cases of giant cell fibroblastoma (GCF), a rare mesenchymal tumor occurring predominantly in the first decade of life, is presented. This disease presented as a painless, slowly enlarging, subcutaneous mass. The tumor recurred locally in 47% of the patients; however, metastasis was not detected. On microscopic examination, GCF showed an unique combination of spindle cell patterns, pleomorphic and multinucleated giant cells, myxoid areas, and distinctive sinusoid-like spaces. This unrecognized histomorphologic picture led to a misdiagnosis of sarcoma in 40% of the cases. The histogenesis of this lesion remains uncertain; however, based on both clinical and morphologic similarities, it is proposed that GCF is a juvenile form of dermatofibrosarcoma protuberans (DFSP).