Leprosy, or Hansen's disease, is a chronic multisystem disease that is caused by Mycobacterium leprae, an acid-fast bacillus. The highest incidence of the disease is in areas of South America, Africa, and Asia. It is not rare in children. The clinical manifestations of this illness depend on the host response to infection. At one end of the spectrum is lepromatous leprosy (LL), which represents a diminished host response to the leprosy bacillus. Cutaneous lesions in this form of the disease vary. Nodular lesions of the earlobe, as shown, are particularly common in lepromatous leprosy. LL is the form most likely to cause widespread nerve damage and ocular disease.