The case of a glomus tumour

A 46 year old man presented to the dermatology clinic with a seven year history of intermittent pain under the fingernail of his left fourth proximal digit that was noticeably exacerbated by cold weather. Examination revealed a tender and subtle 3 mm circular dusky blue lesion under the nail (fig 1⇓). This was excised and histologically confirmed as a glomus tumour. This is a rare smooth muscle neoplasm, most common in subungual sites and the fingers and toes. It arises from the glomus body—a thermoregulatory component in the dermis. This diagnosis can be made on history alone: a subungual lesion with pain induced by cold is pathognomonic of glomus tumour. Treatment is by excision of the tumour.