Cutaneous manifestations of tuberculosis.

Cutaneous involvement is a rare manifestation of tuberculosis (TB). The correct diagnosis is often significantly delayed because cutaneous TB is not routinely considered in the differential diagnosis or because investigations fail to reveal the presence of Mycobacterium tuberculosis. The clinical features of cutaneous TB are diverse, and result from exogenous and endogenous spread of M. tuberculosis and from immune-mediated mechanisms. The recognition of cutaneous TB is important, as the diagnosis is frequently overlooked resulting in delayed treatment.