Solitary fibromatosis of bone. A rare variant of congenital generalized fibromatosis. Congenital generalized fibromatosis is part of the spectrum of the fibromatoses of infancy and childhood. The lesions are usually multiple and fibrous in nature. They may appear in virtually every organ outside the central nervous system. Congenital generalized fibromatosis can be limited to the skeleton and rarely manifests itself as a solitary bone lesion. Solitary osseous lesions often behave differently than multiple osseous lesions. Solitary lesions often do not regress without treatment and can have a high incidence of recurrence with less than marginal excision. Multiple osseous lesions often regress without treatment. 