The pathology of cutaneous leishmaniasis in the Sudan: a comparison with that in other geographical areas.

The pathology of cutaneous leishmaniasis (CL) caused by Leishmania major zymodeme LON 1 in the Sudan was compared with that caused by L. major zymodeme LON 4 in Saudi Arabia and with that already described for L. tropica infections in Iran and for localized CL in the New World. The lesions were classified according to Ridley's five histological types. Most of the lesions in the Sudan and Saudi Arabia were of types B and C, characterized, respectively, by diffuse macrophage necrosis and focalized necrosis. B was the most common type in Nicaragua and Guyana whereas responses of types A (in which there are heavily parasitized macrophages without necrosis) and D (reactive tuberculoid) were the most frequent in Iran. The type-E response, which is similar to D but with virtual absence of plasma cells, was uncommon in all areas. The type-D reaction is a chronic relapsing disease when associated with L. tropica but not when associated with L. major. The major differences in the pathology of CL in different geographical areas most probably relate to differences in the Leishmania species involved. Minor differences, however, not only occur between patients from the same area but may also occur, with time, in the same patient. Detailed comparison between areas is therefore difficult; lesions on one patient may heal asynchronously and show different histological types at any point in time and rebiopsy from the same lesion during healing reveals changes from one histological type to another.