Familial occurrence of infantile myofibromatosis.

Two brothers with multicentric infantile myofibromatosis (IM) are reported. In both, tumors were present at birth; the tumors regressed spontaneously, but new lesions developed throughout the follow-up periods of 15 and 8 years. Immunohistochemically, the nodules were found to be positive for vimentin and actin, but negative for desmin and S-100 protein; these findings support the myofibroblastic nature of IM. A literature review revealed nine additional families with IM in more than one family member. Although the occurrence of IM in eight sets of siblings, with consanguinity in two of them, favors an autosomal recessive mode of inheritance, the disorder also has been well documented in half-sisters and in successive generations, which makes autosomal dominant inheritance a more plausible explanation.