Multiple congenital familial smooth muscle hamartoma in two siblings

Smooth muscle hamartoma (SMH) is a cutaneous malformation mainly composed of a disorganized proliferation of normal muscle fibers that arise from arrector pili. It usually presents as a single congenital lesion that frequently involves the back and the lower limbs. Unusual clinical presentations, such as atypical localizations, multiple disseminated lesions, and generalized forms have been rarely described. In 2001, Gualandri et al. reported the presence of multiple SMH in three members of the same family, namely two brothers and their mother. This is, as far as we know, the only familial case reported in the English literature. We herein describe a similar case affecting two siblings who presented with identical congenital lesions in the same location.