Secondary tuberculosis of the skin. Clinical features and problems in laboratory diagnosis.

One hundred patients with secondary skin tuberculosis--59 with lupus vulgaris (LV), 27 with scrofuloderma (SD), and 14 with tuberculosis verrucosa cutis (TVC)-were included in this study. The buttocks and lower limbs were seen to be important sites of involvement in LV, besides the occurrence over the face. An active focus of tuberculosis was present in 18, a past history of pulmonary tuberculosis in 8, and intrafamilial tuberculous infections in 21. Histopathology and culture for Mycobacterium tuberculosis were done in all the cases. Guinea pig inoculation was done in 11. The poor results of these investigations have been highlighted and discussed with reference to studies done in the past by other workers. The need for improvement in laboratory techniques is suggested.