By Gary M. White, MD

Frictional melanonychia

Frictional melanonychia (FM) or frictional longitudinal melanonychia is the formation of longitudinal melanonychia (LM) from chronic friction by shoe ware. The process is similar to frictional melanosis.


FM is seen usually of the 5th toe, but of the 4th toes as well. Some patients may have it on both feet. Usually the lateral portions of the smaller toes are affected. The adjacent skin may be calloused or even show the formation of corns from the pressure.


No treatment is needed. If desired, a change in footwear to reduce/eliminate friction may be recommended. If there is any question about the diagnosis, a biopsy should be performed.

Additional Pictures

Frictional melanonychia


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