Multifocal infantile myofibromatosis and generalized fibromuscular dysplasia in a child: evidence for a common pathologic process?

Infantile myofibromatosis (IM) is a condition characterized by the formation of spindle cell tumors of skin, soft tissue, and viscera. Although small vessel involvement by the process is a frequently identified and indeed diagnostically useful histological finding, involvement of large vessels is not widely reported. Fibromuscular dysplasia (FMD) is a noninflammatory arteriopathy characterized by intimal, medial, and/or adventitial fibroplasias leading to luminal compromise and aneurysm formation. Although venous disease has been reported, involvement of arterioles and viscera has not been identified. We report a patient in whom IM was diagnosed, on the basis of multiple soft tissue tumors present from birth, who subsequently developed generalized and ultimately fatal FMD. These two conditions exhibit overlapping pathologic features, including pronounced intimal fibroplasia. Their occurrence in a single individual may provide insights into the pathogenesis of both conditions, suggesting that they represent part of the same spectrum of vascular myofibroblastic proliferations.