**6. Clinical presentation**

The initial stage of leprosy is non-specific presenting with one or more hypopigmented macules.

There have been four noted immunologic leprosy reactions. Type 1 reaction represents a hypersensitivity reaction to M. leprae antigens clinically characterized by sudden onset of urticarial swelling of the leprous skin lesions. It may also be associated with acute and very painful neuritides with loss of sensory and motor function.

Pathophysiologically, type 2 reaction (Syn. erythema nodosum leprosum) is characterized by the occurrence of painful violaceous- erythematous cutaneous or subcutaneous nodules. Type 3 reaction (Syn. Lucio's phenomenon).

Myalgia, arthralgia, and osseous pain are symptoms associated with a type 2 reaction [13].

The first leprosy classification by WHO was applied in 1966 based upon the histological picture – the Ridely-Jopling classification. It shows two forms of leprosy – its mild and severe defect of cell-mediated immunity: tuberculoid (paucibacillary) and lepromatous (multibacillary) leprosy with the following subgroups: borderline tuberculoid (BT), borderline lepromatous (BL) and borderline lepromatous leprosy (BL) [14]. This classification is detailed earlier in the chapter.
