[Fibromatoses and related disorders in childhood].

A retrospective study of fibromatoses and related diseases was performed on a series of 34 children. Aggressive forms of fibromatoses similar to those in adults as well as typical forms of childhood fibromatoses and fibrous proliferations, such as sternocleidomastoid tumor, infantile myofibromatosis, digital fibromatosis and fibrous hamartoma were observed. Immunohistochemistry revealed muscle specific actin in eleven out of 13 cases, including hyaline cytoplasmic inclusions in digital fibromatosis. In two patients with infantile myofibromatosis a coexpression of actin and desmin was found. One of two cases of infantile type of aggressive fibromatosis was weakly actin positive whereas the other was negative. This result suggests poorly differentiated character of cells in infantile fibromatosis. Clinicopathologic correlation showed that extraabdominal fibromatoses had a strong propensity for local recurrence. Multiple lesions affecting different muscle groups were diagnosed in two boys. Abdominal fibromatosis affected two girls and two boys, in contrast to adult forms which occur exclusively in women.