"Localized" leishmania lymphadenitis: a light and electron microscopic study.

Nineteen cases of "localized" leishmania lymphadenitis without any evidence of visceral leishmaniasis are reported. Fifteen males and 4 females aged 5 to 30 years have presented with localized lymphadenopathy of up to 3 months duration. The disease has a seasonal incidence of late summer to mid-winter. Cutaneous leishmaniasis even when present, usually was overlooked. Lesions of cutaneous leishmaniasis were absent in 3; healed in 1; small, similar to insect bites in 5; classic in 3; lupoid in 1 and unknown in 6 patients. Serum leishmanial antibody determination by IFAT performed on 12 cases were positive. Toxoplasma serology was negative. Histological picture of one lymph node biopsy showed an (anergic) intact histiocytic response characterized by thousands of intracellular amastigotes, no necrosis and inconspicuous plasma cells. In 17 biopsies the picture was that of histiocytic granulomata with varying degrees of necrosis, moderate numbers of amastigotes in several foci, fibrosis and varying numbers of plasma cells. One biopsy from a lupoid case shows numerous epitheloid granulomata, no organisms, no necrosis and inconspicuous plasma cells. Electron microscopy has been performed on 8 biopsies to confirm leishmania amastigotes. Differential diagnosis from toxoplasmosis and cat-scratch disease is discussed. Histological types of responses in the lymph nodes are comparable to those described in cutaneous leishmaniasis: an anergic response with intact macrophage granuloma, a histiocytic response with necrosis, and a lupoid type of response with epithelioid granulomas.