Cutaneous tuberculosis due to multidrug-resistant tubercle bacilli and difficulties in clinical diagnosis.

This report describes 6 HIV-negative patients including 5 children with scrofuloderma and an adult with lupus vulgaris, out of a total of 303 cases of cutaneous tuberculosis seen during a 4½-year period, who showed a positive tuberculin test and granulomatous histopathology, but failed to respond to first-line antitubercular therapy. They were suspected to have multidrug-resistant infection as no other cause could be ascertained. Tissue aspirate or biopsy was sent for histopathology and culture. Mycobacterium tuberculosis was isolated from the aspirate in three patients and sputum in one with associated pulmonary tuberculosis. Drug susceptibility tests showed that all isolates were resistant to rifampicin and isoniazid, and one each additionally to streptomycin and ethambutol, respectively. In two, culture was unsuccessful. All were administered second-line antitubercular drugs. Clinical improvement was appreciable within 2 months as weight gain, and regression of ulcers, swellings and plaques. Two completed the recommended 24 months of therapy. Multidrug-resistant cutaneous tuberculosis should be suspected in patients with no response to first-line drugs, with clinical deterioration, and where other causes of treatment failure are not forthcoming. Owing to poor isolation rates on culture and low sensitivity of molecular tests, in such cases, a trial of second-line anti-tubercular drugs may be justified for a reasonable period of 2 months. Where facilities permit, culture and drug sensitivity tests should be done before starting treatment. Culture positivity is better from aspirated material.