Lichen Scrofulosorum Presenting as Pyrexia of Unknown Origin

Cutaneous tuberculosis forms a subset of extra pulmonary tuberculosis. It accounts for about 1.5% of all the cases of extrapulmonary tuberculosis. Lichen Scrofulosorum is a rare form of cutaneous tuberculosis. It is usually seen in children or young adults and an important marker of occult tuberculosis. Usually, the eruption appears in children and adolescents with strong immune sensitivity to Mycobacterium tuberculosis and consists of tiny follicular papules. Underlying systemic involvement is more common in children, compared with adults. We report a case of 3 years old boy who was investigated for pyrexia of unknown origin and finally diagnosed as Lichen Scrofulosorum associated with tuberculous lymphadenitis of mediastinal lymph nodes. A skin biopsy showed extensive tuberculoid granulomas surrounding hair follicles which were consistent with the diagnosis of Lichen Scrofulosorum. The child was treated with antitubercular drugs and it showed improvement within 2 weeks of starting treatment with resolution of skin lesions.