Eccrine Angiomatous Hamartoma Occurring on the Nail Bed

A 71-year-old woman was referred to our clinic with a 2-month history of pain and exudate from her right first toe. Physical examination revealed a subungual nodule that elevated the nail plate and produced distal onycholysis. We performed onychectomy and removed the nodule. A histopathological specimen from the nodule showed hyperkeratosis and acanthosis in the epidermis, papillomatosis and dilated vessels in the superficial dermis, and aggregation of eccrine glands in the mid-dermis. Based on these findings, a diagnosis of eccrine angiomatous hamartoma (EAH) was made. EAH is a rare cutaneous hamartoma that is histologically characterized by proliferation of eccrine glands and vascular components. To our knowledge, EAH occurring in the subungual region has not been reported. The pathogenesis of acquired EAH has not been completely elucidated, but several cases have been reported to be caused by external stimuli. Although the subungual area generally has no sweat glands, our case suggests that a traumatic stimulus can induce EAH anywhere including regions where sweat glands are normally not found.