Tuberculoid leprosy or sarcoidosis? A diagnostic dilemma

During an intensive survey in a leprosy endemic area in South India, a young male adult was detected with infiltrated skin lesions and diagnosed as a case of major tuberculoid leprosy. The presence of leprosy in the individual could not be clinically established, despite a histological diagnosis of tuberculoid leprosy made on his skin biopsy. In a eighteen year follow up during which he was examined on six occasions, the skin patches continued very much the same in appearance with a progressive increase in size; he was re-biopsied from the same lesion thrice and was declared tuberculoid or borderline tuberculoid leprosy. At no time did the clinical findings warrant a diagnosis of leprosy but suggested that it could be sarcoidosis or lupus vulgaris. The biopsy done for the fifth time from the same skin lesion during the seventh examination and from the site of Kveim test confirmed the condition to be sarcoidosis.