Acquired dermal melanocytosis confined to the palm with a review of published cases of acquired dermal melanocytosis on the hands.

Acquired dermal melanocytosis (ADM) classically occurs on the face. However, extrafacial ADM including palmar ADM has been reported on rare occasions. We present the first report of ADM confined to the palm without ADM lesions in other regions in a 30-year-old Japanese woman. The patient presented with several interspersed macules up to 1 cm in diameter with poorly defined margins, containing faint slate-gray spots 1-2 mm in diameter, on the left palm near the first and second fingers and on the palmar side of the first finger near the metacarpophalangeal joint. These slate-gray spots were prominent on and around palmar creases and on wrinkles on the metacarpophalangeal joint. The patient was right hand-dominant. Histopathological examination revealed scattered spindle-shaped cells with melanin granules and melanophages in the upper to middle dermis. Pigment-bearing spindle-shaped cells were demonstrated to be dermal melanocytes because of positive staining for Melan-A after melanin removal. We review the published work for ADM on the hands.