An Interesting Case of Ingrowing Hair.

Cutaneous pili migrans is a rare condition caused by embedded hair shafts or fragments which presents as a mobile black linear rash and is easily confused with cutaneous larva migrans. "Ingrowing hair", in which the hair shaft grows inside the skin and burrows into the uppermost dermis rather than exiting the skin, is much rarer, and only 8 cases have been reported thus far, all in Asian men. We report a case of a 22-year-old Chinese male with a 4 cm-long black linear rash that migrated from the anterior abdomen to the left lower abdomen. The black lines represented hair shafts with follicular structures. The lesion disappeared immediately after hair removal. No recurrence occurred in 4 weeks of follow-up. To our knowledge, this is the first description of ingrowing hair occurring in the abdomen.