Tuberculosis (TB) is a mycobacterial infection that most frequently occurs due to infection with Mycobacterium tuberculosis, an acid-fast bacillus. The high prevalence of TB worldwide (one-third of the world population), its transmissible nature, and the significant morbidity and mortality associated with this infection account for the status of TB as a major public health concern . (See "Epidemiology of tuberculosis", section on 'Global burden'.)
Cutaneous lesions are relatively uncommon manifestations of TB, occurring in only 1 to 2 percent of infected patients. The clinical findings vary; inflammatory papules, verrucous plaques, suppurative nodules, chronic ulcers, or other lesions may be seen. Factors such as the pathway of bacterial entry into the skin, the host’s immune status, and the presence or absence of host sensitization to M. tuberculosis influence the presentation of TB in the skin.
The cutaneous disorders associated with TB will be reviewed here. The epidemiology and microbiology of TB, extracutaneous TB, and the general principles of the treatment of TB are reviewed separately. (See "Epidemiology of tuberculosis" and "Microbiology and pathogenesis of tuberculosis" and "Treatment of pulmonary tuberculosis in HIV-negative patients".)
Cutaneous TB was first documented in 1826, when Laennec reported his own "prosector's wart," a lesion that likely represented tuberculosis verrucosa cutis, a variant of TB that results from direct entry of the organism into the skin . However, the causative organism of TB was unknown until Robert Koch discovered Mycobacterium tuberculosis in 1882 . Subsequently, the bacillus was detected in cutaneous lesions . (See 'Clinical variants' below.)
Cutaneous TB is a relatively uncommon manifestation of TB, accounting for only 1 to 2 percent of all cases [5-7]. Similar to other forms of TB, a resurgence of cutaneous TB has been noted in parts of the world where human immunodeficiency virus (HIV) infection and multidrug-resistant TB are prevalent [8-10]. (See "Epidemiology of tuberculosis", section on 'Global burden'.)