Infantile myofibromatosis is a rare disorder characterized by multiple fibroblastic benign tumors that are derived from connective tissue and involving skin, striated muscles, bones and viscera. The tumors are present at birth or develop during the first weeks of life. Following initial growth and proliferation of tumor cells, the tumors usually regress and eventually spontaneously disappear. In some instances, new tumor development may occur after long periods. Patients with single or multiple tumors without visceral involvement generally have a benign disease course; therefore, the prognosis is excellent. However, in infants with severe or widespread visceral involvement, the tumors may significantly compress, obstruct, and impair the functioning of internal organs. Thus, the mortality rate is high among patients with visceral nodules.

Infantile myofibromatosis-1 (IMF1) is caused by mutations in the PDGFRB gene.