Lichen scrofulosorum: a rare manifestation of a common disease.

Tuberculids develop as hypersensitive immunologic reactions in the skin to an occult internal focus of tuberculosis. These eruptive lesions are due to hematogenous dissemination of bacilli in a host with a high degree of immunity against Mycobacterium tuberculosis. Although rare, these specific lesions are important diagnostic markers of tuberculosis. Lichen scrofulosorum is one of the recognized tuberculids, usually seen in children and young adults. We report three children with lichen scrofulosorum; in two children it developed during treatment of tuberculosis. The appearance of lichen scrofulosorum after initiation of treatment due to a probable increase in cell-mediated immunity is emphasized.