Although many patients with indeterminate leprosy heal spontaneously, all such patients should receive chemotherapy. The cell-mediated immunity of patients with tuberculoid leprosy is intact. Patients who have lepromatous leprosy are anergic and show severely impaired cell-mediated immunity. Skin lesions of patients with tuberculoid leprosy contain predominantly helper T cells, well-formed granulomas, and few organisms, whereas the lesions of lepromatous leprosy are practically devoid of granulomas and helper T cells, containing instead suppressor T cells and numerous bacilli. The presence of a few large, asymmetrical, well-defined skin lesions characterizes tuberculoid leprosy.
Neurologic involvement is limited to a few peripheral nerves.
Although the damage to these nerves can be severe, the overall prognosis is good. A biopsy that shows well-formed granulomas but only very few organisms establishes the diagnosis. A patient with lepromatous leprosy can serve as the host for an enormous bacterial burden because organisms multiply unchecked. The numerous symmetrical skin lesions are small and ill defined. At times, the entire skin surface can be involved, yielding a diffuse, waxy appearance.