Infantile (desmoid type) fibromatosis with extensive ossification

Solitary congenital or infantile (desmoid-type) fibromatosis is a benign, but potentially locally aggressive lesion that is best treated by wide local excision. It has been confused with congenital fibrosarcoma and other soft-tissue malignant tumors. To our knowledge, ossification has not been reported previously in this lesion. A case of ossifying solitary congenital fibromatosis is presented with a discussion of its differential diagnosis and histologic distinction from other soft-tissue lesions, including soft-tissue and parosteal osteosarcoma.