Cutaneous tuberculosis: diagnostics and therapy

Tuberculosis is an infectious, granulomatous disease caused by Mycobacterium tuberculosis . It is still a major global health problem for both developing and developed countries. In 2009, around 9 million of new cases of tuberculosis around the world and 1.7 million deaths were noted. All countries are affected, but the majority of cases occur in Africa (30%) and Asia (50%). Cases reported in Europe represent approximately 6% of all those reported worldwide. Cutaneous tuberculosis may manifest either as a primary (previously uninfected host) or secondary (pre-sensitized host) forms. There is a wide spectrum of clinical pictures with lupus vulgaris (high immunity) at one end and tuberculosis cutis orificialis (low immunity) at the other, bridged by tuberculosis verrucosa and scrofuloderma (moderate immunity). Cutaneous tuberculosis is one of the most difficult diagnoses to make for dermatologists, not only because they have to consider a wide differential diagnosis but also because of the difficulty in obtaining microbiological confirmation. The diagnosis relies mainly on histopathology, culture on Löwenstein-Jensen medium or the radiometric TB culture system and amplification of bacterial DNA with polymerase chain reaction (PCR). Despite all the advances in microbiology, the isolation of M. tuberculosis in culture is still a gold standard. Therapy of tuberculosis is also complicated. Both pulmonary and extrapulmonary tuberculosis are treated with similar drugs according to World Health Organisation Guidelines. There are around 0.5 million new multidrug resistant cases of tuberculosis (MDR-TB) every year. Treatment of MDR-TB is more challenging and the cure rates range 50% to 70%.