Cutaneous tuberculosis: a diagnostic and therapeutic study of 20 cases.

Cutaneous tuberculosis is showing a resurgence. It continues to be one of the most elusive and difficult diseases to diagnose in dermatological practice. We sought to describe the clinical manifestations, laboratory features, and antituberculous therapy in cases of cutaneous tuberculosis. Twenty cases of cutaneous tuberculosis were observed in this study. Of the 20 cases, seven were in women (35%) and 13 were in men (65%). There were eight (40%) cases of lupus vulgaris, four (20%) cases of orificial tuberculosis, four (20%) cases of tuberculosis verrucosa cutis, two (10%) cases of scrofuloderma, and two (10%) cases of primary inoculation tuberculosis. In total, 20 strains of acid-fast bacilli were isolated by culture in Löwenstein-Jensen medium at 37°C. Mycobacterial species identification by polymerase chain reaction (PCR) assay showed that all strains were Mycobacterium tuberculosis. In vitro susceptibility testing by use of absolute concentration method showed that the 20 strains were sensitive to rifampin, ethambutol, and isoniazid; however, two strains were resistant to streptomycin. All of the patients responded favourably to antituberculous treatment. Cutaneous tuberculosis is a skin disease that should still be thought much of in mainland China, and in this study lupus vulgaris is the most common clinical presentation.