Molecular pathology and histopathological findings in localized leishmania lymphadenitis.

BACKGROUND A rare variant of Leishmaniasis is Localized Leishmania Lymphadenitis which has been occasionally reported from south-eastern parts of Iran. So far, no molecular assay has been performed for diagnosing this variety of Leishmaniasis. METHODS Nineteen lymph node paraffin blocks were collected from 1994 to 2007. Parasite load count and histopathological patterns reported on Hematoxylin-Eosin and Giemsa stained slides.DNA extraction was carried out just on the remaining available 7 lymph node paraffin blocks according to QIAamp DNA FFPE kit instructions. A pair of primers and a probe were designed for rRNA ITS region with Allele ID 6.0 software, followed by real time PCR amplification. RESULT The most common histopathological pattern was necrotizing granuloma with few Leishman bodies. Parasite load was the highest in submental lymph node (3 ± 1.41 per oil field) which was significantly higher compared to cervical and inguinal nodes (P < 0.05). Absolute load of parasite DNA was detectable in all 7 cases. The positive cases revealed a 201 bpamplicon after electrophoresis of end product which was confirmative for Leishmania tropica. CONCLUSION Real time PCR revealed Leishmania tropica as the etiologic agent of Localized Leishmania Lymphadenitis. Although this molecular method is a sensitive diagnostic tool, histopathological findings are still important.