Papuloverrucous colloid milium: an occupational variant.

We report a case of adult colloid milium in a 47-year-old mechanic with a long history of professional contact with lubricating oils and of sun exposure. In addition to the typical translucent papules seen on the forehead, there were warty papules on the backs of both hands with unusual histological and ultrastructural features: marked hyperplasia of the epidermis with orthokeratotic hyperkeratosis and papillary deposits of colloid material that were contiguous with the basal layer of the epidermis. The hand lesions caused by occupational exposure to mineral oils and solar radiation represent an occupational variant of adult colloid milium.