Vascular changes in human leishmaniasis: a light microscope and immunohistological study.

The study of human cutaneous leishmaniasis from Saudi Arabia (37 cases), and of Sudanese mucosal (52 cases) and visceral (27 cases) leishmaniasis revealed the occurrence of vascular alterations. Vasculitis with or without fibrinoid necrosis and fibrin thrombi were found in both the arteries and veins within the area of inflammation in cutaneous and mucosal leishmaniasis; whereas subendothelial oedema, hyalinosis and intimaproliferation were seen in the small arteries of the various organs in visceral leishmaniasis. Immunoperoxidase staining of the cutaneous leishmaniasis lesions showed the presence of IgG and IgA within the endothelial cells, in the media, and in the perivascular space of the diseased vessels. The formation of immune complexes, locally in cutaneous and mucosal leishmaniasis and circulating in visceral leishmaniasis, is considered responsible for these vascular lesions.