Cutaneous leishmaniasis of the New World: diagnostic immunopathology and antigen pathways in skin and mucosa.

Non-specific chronic inflammation and/or granulomatous reaction are the main histopathological manifestations of cutaneous and mucocutaneous leishmaniasis of the New World. Plasma cell infiltration associated with collagen and vascular changes are data suggestive but not diagnostic of the disease. Specific diagnosis is only possible through demonstration of the parasite in the tissue examined. It is noteworthy that the parasites are usually scanty and difficult to demonstrate in the lesions. Biopsies from 40 patients with cutaneous or mucocutaneous leishmaniasis were examined using the immunofluorescence and immunoperoxidase techniques in order to demonstrate the parasite and/or antigen in the tissues. Nineteen biopsies showed non-specific chronic inflammation and 21 a granulomatous reaction. Parasites were found in 20% of the routine biopsies. The positivity through indirect immunofluorescence was 88.46% in frozen sections of fresh material and 89.28% in paraffin embedded tissue. The antigen positivity with the immunoperoxidase technique was 64.51%. Antigen was detected as amastigotes and also as diffuse material in the macrophage cytoplasm and adsorbed in the epithelial basement membrane and vessel walls. There was no difference in the positivity of antigen according to the type of inflammatory reaction.