Lichen planopilaris (LPP) is a primary lymphocyte-mediated scarring alopecia of unknown etiology. In this condition, lymphocytes attack the epithelium of the infundibula and isthmus areas of hair follicles and sometimes the interfollicular epidermis. The histologic changes are identical to those seen in lichen planus, that is, interface changes consisting of bandlike lymphocytic inflammation with necrotic keratinocytes. With time there is perifollicular fibrosis and decreasing inflammation. Sebaceous glands are destroyed. Ultimately hair follicles are also destroyed. The follicular antigen(s) targeted by these lymphocytes are not known.