Infantile myofibromatosis is a disorder of mesenchymal proliferation characterized by the development of benign tumors in the skin, muscle, bone, and viscera. Soft tissue lesions may regress spontaneously. Visceral lesions are associated with high morbidity and mortality (summary by Martignetti et al., 2013). For a discussion of genetic heterogeneity of infantile myofibromatosis, see IMF1 (228550).

Kosaki overgrowth syndrome (KOGS) is characterized by a facial gestalt involving prominent forehead, proptosis, downslanting palpebral fissures, broad nasal bridge, thin upper lip, and pointed chin. Affected individuals are tall, with an elongated lower segment, and have large hands and feet. Skin is hyperelastic and fragile. Patients exhibit progressive dilatory and vascular changes in basilar/vertebral and coronary arteries starting in the teenage years (Takenouchi et al., 2015; Takenouchi et al., 2021).

A rare inherited form of myofibromatosis caused by autosomal dominant mutation(s) in the PDGFRB gene, encoding platelet-derived growth factor receptor beta. The condition is characterized by the onset of solitary or multicentric benign tumors in the skin, striated muscles, bones, and viscera. The lesions may be present at birth or become apparent in early infancy or even occasionally in adult life.