Chronic amastigote-negative cutaneous leishmaniasis: A clinical, histopathologic and molecular study of 27 cases with emphasis on atypical and pseudolymphomatous presentations

BACKGROUND: Chronic amastigote-negative cutaneous leishmaniasis (CL) is a diagnostic challenge, as the parasite load may be low, or absent in biopsy tissue sections. METHODS: A series of consecutive biopsy specimens, taken from 130 patients with a diagnosis of granulomatous dermatitis of unknown etiology, were reviewed. Polymerase chain reaction (PCR) was carried out for Leishmania-specific DNA. RESULTS: A total of 27 of 130 samples were positive for Leishmania-specific DNA. In only 3 patients was a clinical diagnosis CL made. The lesions were, single or multiple nodules or plaques of many months duration. Histopathologically, a tuberculoid granulomatous dermatitis was the least common denominator in every case, whilst in 5 cases a heavy lymphoid component was predominant. One patient had a concurrent cutaneous marginal zone lymphoma (MZL), the additional PCR study showed the presence of Leishmania DNA in tissue. CONCLUSIONS: The results of this study expand on previous observations as to the deceptive clinicopathologic manifestations of chronic CL, confirming the diagnostic value of PCR analysis for Leishmania DNA in unspecified granulomatous dermatitides. We also suggest that, in countries where Leishmaniasis is endemic, PCR for Leishmania-specific DNA be performed in any idiopathic pseudolymphomatous. More compelling evidence as to whether chronic Leishmania infection is implicated in the pathogenesis of some cutaneous MZL is warranted by further studies.