Buruli ulcer is a chronic, progressive skin disease caused by infection with Mycobacterium ulcerans. It is currently considered to be one of the neglected tropical diseases; less common than tuberculosis but more common than leprosy. The initial lesion is a painless subcutaneous nodule, usually less than 5 cm diameter and adherent to skin. The nodule typically breaks down centrally after days to weeks forming an ulcer with undermined edges. Thus, the external appearance of the ulcer underestimates the true size of the affected area. The patient remains well and there is no pain unless secondary bacterial infection occurs. Other forms of M. ulcerans disease include a firm plaque lesions that behaves in the same way as the nodule or an oedematous lesion that is more aggressive and extends rapidly resulting in a very large ulcer.
Any age group can be affected by Buruli ulcer diseases, but the incidence peaks at 5 to 15 years. Ulcers are most frequently on the limbs but can be on the trunk or head, sometimes with catastrophic consequences such as loss of sight or loss of breast or genital tissue. Healing close to a joint can result in contracture, and sometimes there is so much tissue destruction on a limb that amputation is unavoidable. Occasionally osteomyelitis occurs in bone adjacent to a skin lesion but involvement of other organs is rare. Disseminated disease with HIV has been reported.