Clinical and morphological variants of cutaneous tuberculosis and its relation to Mycobacterium species.

Cutaneous tuberculosis forms a small proportion of extrapulmonary tuberculosis. The incidence of cutaneous tuberculosis has fallen from 2% to 0.15% in India whereas it is rare in developed countries. The present study is an attempt at finding out the Mycobacterium species associated with cutaneous tuberculosis. A total of 51 cases of clinically suspected cutaneous tuberculosis were studied over a period of 18 months from July 1997 to December 1998. Of these, 32 (62.75%) were Scrofuloderma cases, 12 (23.52%) cases of Lupus vulgaris and 7 (13.73%) were Tuberculosis verrucosa cutis (TBVC) cases. Twenty nine mycobacterial isolates from 51 specimens gave an isolation rate of 56.86%. These were subjected to a battery of biochemical tests for identification to species level. Twenty six out of 29 isolates were identified as Mycobacterium tuberculosis, two were identified as Mycobacterium Scrofulaceum and one Mycobacterium avium complex was isolated. Sixteen Mycobacterial isolates were recovered from Scrofuloderma cases, 9 were isolated from Lupus vulgaris and 4 from TBVC cases. The three atypical mycobacterial isolates were recovered from Scrofuloderma cases. Though Mycobacterium tuberculosis was the most common isolate, Mycobacterium scrofulaceum and Mycobacterium avium complex were also isolated in the present study.