Smooth muscle hamartoma of the hard palate.

A small polypoid lesion was removed from the incisive papilla region of a healthy female aged 8 years. It was composed of non-cycling smooth muscle fibres that were immunoreactive for various muscle antigens, surrounded by basement membrane containing collagen IV, arranged as bundles and mixed with CD34(+) interstitial cells, mast cells, dendrocytes and nerves. The lesion could be attributed to dysgenesis affecting media of vessels emerging from the incisive foramen. Intra-oral smooth muscle hamartomas tend to favour regions featuring complex developmental events.