Multiple rhabdomyomatous mesenchymal hamartomas of skin.

A case of multiple rhabdomyomatous mesenchymal hamartomas is presented. The patient is a black male infant, the product of an uncomplicated term gestation and delivery. At birth, there were numerous polyps distributed over the periorbital and periauricular areas bilaterally. Some appeared fingerlike with constrictions below their tips. Others were branched or globular in shape. These projections showed spontaneous and independent movement, particularly during feedings. On histopathologic examination, the polyps were covered by squamous epithelium and contained normal follicular units. Bundles of skeletal muscle were present in the reticular dermis, extending into the subcutis. Regular cross-striations were seen in these muscle fibers. In some specimens, the muscle bundles formed a solid, central core. Skeletal muscle histochemical stains confirmed the presence of both types 1 and 2 muscle fibers. Electron microscopy revealed a normal skeletal muscle banding pattern. This case is the first report of multiple rhabdomyomatous mesenchymal hamartomas of skin. Functional skeletal muscle with spontaneous movement is part of the clinical picture.