Buruli ulcer: clinical pathological study of 23 patients in Lambaréné, Gabon.

Within one year 23 patients in Lambaréné (Gabon) were diagnosed as having a Buruli ulcer (advanced cases with undermined margins). The majority of the ulcers were found in children; with the exception of one ulcer on the thorax, all ulcerations were localised at the extremities. The mode of transmission could not be clarified; extensive water tests for Mycobacterium ulcerans were negative. Observed under an electron microscope, M. ulcerans has a similar structure as other mycobacteria. Exudative inflammatory processes predominate in the ulcer floor. The small blood vessels play a considerable role in the pathological process. The mycobacteria are present in this layer, below this there is widespread necrosis of adipose tissue. The margin of the ulcer displays a granulomatous inflammatory reaction. The cytological characteristics of the mesenchymal reaction of a Buruli ulcer are described with the aid of electron microscope photographs.