Leprosy is a chronic infectious condition caused by Mycobacterium
leprae(M. leprae). It is endemic in many regions of the world and a
public health problem in Brazil. Additionally, it presents a wide spectrum of
clinical manifestations, which are dependent on the interaction between M.
leprae and host, and are related to the degree of immunity to the bacillus. The
diagnosis of this disease is a clinical one. However, in some situations
laboratory exams are necessary to confirm the diagnosis of leprosy or classify
its clinical form. This article aims to update dermatologists on leprosy,
through a review of complementary laboratory techniques that can be employed for
the diagnosis of leprosy, including Mitsuda intradermal reaction, skin smear
microscopy, histopathology, serology, immunohistochemistry, polymerase chain
reaction, imaging tests, electromyography, and blood tests. It also aims to
explain standard multidrug therapy regimens, the treatment of reactions and
resistant cases, immunotherapy with bacillus Calmette-Guérin (BCG) vaccine and
chemoprophylaxis.