A case of herpetiform appearance of digital mucous cysts.

A digital mucous cyst (DMC) is clinically characterized by a round to oval, translucent, smooth nodule localized to the dorsal aspect of the distal digits near the distal interphalangeal joint. It usually presents as a solitary lesion, and multiple lesions are uncommon. An 88-year-old man presented with herpetiform translucent papules on the right thumb. We first diagnosed the lesion as molluscum contagiosum or herpetic whitlow. Histopathology showed a cystic space containing mucinous material and numerous fibroblasts surrounded by mucinous stroma in the upper dermis. The lining of the cyst wall was not apparent and mucinous material was stained with Alcian blue, indicating a diagnosis of DMC.