Leiomyomatous hamartoma presenting as a congenital epulis

An otherwise-healthy 11-month-old white girl presented with a polyp-like lesion on the anteromedial part of the maxillary alveolar ridge. It looked like a congenital epulis, but histological examination showed fascicles of smooth muscle cells dispersed in collagenous stroma with a few peripheral nerve bundles that were intermingled with smooth muscle fibres. The muscle cells stained strongly for desmin and alpha-smooth-muscle actin. However, S-100 was found only in peripheral nerve bundles. It was therefore a leiomyomatous hamartoma.