Tuberculosis, an infection caused by Mycobacterium tuberculosis bacilli, has existed for millennia, and till today it continues to be a major global public health concern, and in 2015 alone there were estimated 10.4 million new cases. The bulk of the disease globally is pulmonary TB, but the bacilli can affect any other body organ including the skin in the form of extrapulmonary TB in about 8.4–13.7%. This makes tuberculosis of the skin a relatively uncommon infectious disease comprising only 1–2% of the extrapulmonary tuberculosis cases and approximately 0.1–1% of all cutaneous disorders. Cutaneous TB increases with concomitant infection with HIV, an increase in multidrug-resistant TB and the recent rise in the therapeutic use of biologics specifically antitumor necrosis factor (anti-TNF). The clinical presentation depends mainly on the route of infection, cellular immunity, and virulence of the infecting organism. Cutaneous TB is classified into three main categories: exogenous inoculation, endogenous infection, and hematogenous spread.
Infections with atypical mycobacteria occur predominantly in immunocompromised hosts. In immunocompetent hosts, infection follows skin penetration and is usually localized, while there is a tendency for dissemination in immunocompromised patients. The current therapeutic options for cutaneous TB are limited to the conventional anti-TB drugs in addition to some surgical interventions in certain indications (surgical excision of lesions and correction of deformities).
KeywordsCutaneous TB Atypical mycobacteria Exogenous inoculation Endogenous infection Hematogenous spread
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