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. MATHERIALS an‎d 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.