Congenital midline hamartoma: case report with histochemical and immunohistochemical findings.

We report the case of a polypoid nodule on the chin of an infant. Microscopically, the lesion featured numerous pilosebaceous units, eccrine sweat glands, arrectores pilorum muscles, mature adipose tissue, and prominent admixtures of skeletal muscle. This lesion has much in common with the accessory tragus, and is similar to the one reported earlier as rhabdomyomatous mesenchymal hamartoma. We feel the more general term congenital midline hamartoma is preferable, as it encompasses both the clinical and microscopic features of the lesion.