Atypical presentation of Old-World cutaneous leishmaniasis, diagnosis and species identification by PCR

Background The diagnosis of cutaneous leishmaniasis (CL) is traditionally based on microscopic demonstration of amastigote forms in tissue biopsies or smears. However, this method usually presents low sensitivity, and in atypical forms, CL may be overlooked because of similarity to other dermal diseases. Thus, it is necessary to apply specific diagnostic methods as polymerase chain reaction (PCR). Objective To evaluate the possible advantage of PCR in the diagnosis and species identification of CL in patients with atypical clinical presentation. Methods Fifty‐one patients clinically suspected of CL with positive and negative controls were tested. After microscopic examination, extraction of DNA was performed on their smears and analysed by two specific PCR assays for diagnosis and species identification. For these methods, conserved and variable regions of kinetoplastic DNA (KDNA) of Leishmania species have been amplified, respectively. Atypical forms of CL were evaluated among PCR‐positive patients. Results PCR results were positive in 37 out of 51 cases (72.5%), among whom microscopic examination revealed Leishmania amastigotes in only 3 (5.9%). Among these patients, 10 (27%) had atypical presentation of CL; using species‐specific primers, 6 patients had Leishmania major, 3 had Leishmania tropica and 1 patient had no species diagnosis. None of the samples of other dermal diseases revealed positive results (specificity, 100%). All patients were successfully treated by CL‐specific drug regimens. Discussion The results showed that KDNA PCR methods have a higher sensitivity compared with microscopic method. Moreover, PCR could identify the parasite species for specific therapy. Microscopic method had low sensitivity and less value in chronic and atypical CL cases.