Cutaneous tuberculosis.

Cutaneous tuberculosis continues to be one of the most elusive and more difficult diagnoses to make for dermatologists practicing in developing countries. Not only because they have to consider a wider differential diagnosis (leishmaniasis, leprosy, actinomycosis, deep fungal infections, etc) but also because of the difficulty in obtaining a microbiological confirmation. Despite all the advances in microbiology, including sophisticated techniques such as polymerase chain reaction, the sensitivity of new methods are no better than the gold standard, that is, the isolation of Mycobacterium tuberculosum in culture. Even now, in the 21st century, we rely on methods as old as the intradermal reaction purified protein derivative (PPD) standard test and therapeutic trials, as diagnostic tools. In this situation, it is important to recognize the many clinical faces of cutaneous tuberculosis to prevent missed or delayed diagnoses.