Rare Presentation of Pilar Cyst of the Thumb.

Pilar cysts are common cysts on the scalp and hair bearing area of the body. We found one such cyst on the dorsum of the thumb. There have been previous reports of them in the finger tips as a very rare occurrence. The site of this lesion supports the theory of a possible origin from the nail matrix. These lesions, even when found at unusual sites should have pilar cyst as a differential diagnosis. They must always be excised and subjected to careful histopathology to rule out proliferating trichilemmal cysts, which carry a rare risk of malignancy.