ACQUIRED DERMAL MELANOCYTOSIS
By Gary M. White, MD
Late onset dermal melanocytosis: an upper back variant.
Acquired dermal melanocytosis (ADM) represents the presence of dermal melanocytes that become apparent after birth. It usually presents as a large blue/brown patch in the adult. Congenital dermal melanocytosis is called a Mongolian spot.
- Ninety-five percent of patients are women.
- Most patients are Asian, with a high percentage from Japan.
- Fourteen percent of patients have a positive family history.
- Sunlight and female hormones (e.g., pregnancy) may be predisposing factors.
- In the past, PUVA had been reported to precipitate.
Blue patches develop in the teenager or adult. The back is a common site. See also Nevus of Ito.
In fact, there is a variant called late onset dermal melanocytosis: an upper back variant [J Dermatol 1991;18;97]. Blue macules on the upper mid back with onset in middle or old age is characteristic. The initial report was from Japan. Histologic examination shows dermal melanin-containing cells. Electron microscopy shows these cells to be dermal melanocytes. There is a related case report of a woman who had gray-blue pigmentation of the back since birth that slowly grew over time [Dermatology 1999;198;105].
No treatment is needed. Various lasers have been used.
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