[Friction melanosis].

We describe 23 cases of unusual brownish pigmentation occurring over the bony tissues such as clavicle, scapula or vertebrae. There were 19 females and 4 males. The age ranged from 18 to 59, mostly between 20 and 35 years. Since the first observation in 1977, cases gradually increased. The pigmentation usually showed ripple pattern on the upper back and clavicular region, zebra-like pattern over the ribs and postage-stamp-like macule over the vertebral column. Although there was no inflammatory sign such as itching or scaling, histology revealed postinflammatory melanin deposit in the upper dermis. Exceptional detection of amyloid deposit in the papillary layer in one case could be secondary to the slight epidermal damage actually disappeared. The general condition was not affected, and laboratory data remained within normal limits. This unique melanosis should be separated from other pigmentary disorders and macular amyloidosis. We would like to propose the name of friction melanosis, because this condition should be intimately related with the repeated friction by nylon towel or brush, widely used by young peoples in the bathroom.