Comparison of fine needle aspiration and direct skin smear in the diagnosis of acute cutaneous leishmaniasis: polymerase chain reaction as a reference method

Background: Accurate diagnosis of cutaneous leishmaniasis would avoid unnecessary treatment and scar formation. Direct smear is the most common method for the diagnosis of this disease but its negative result could not rule out the infection; so, the need for more sensitive methods is obvious. We conducted this study to compare the efficiency of direct skin smear with smears prepared by fine needle aspiration (FNA) using polymerase chain reaction (PCR) as a reference method. Methods: In this cross-sectional study, which was conducted during two years from May 2008 to May 2010, 33 patients with suspicious acute cutaneous leishmaniasis based on clinical studies were randomly selected. Direct skin smears and FNA smears were taken from each patient and PCR was performed on biopsy samples; the results were then compared. Results: The rate of positive results in each method was as follows: PCR 81.8%, direct skin smear 60.6% and FNA 42.4%. The sensitivity of the direct skin smear was significantly higher than the FNA method (74.1% versus 51.9%, P< 0.001). There was no lesion with a positive result on FNA and negative results on the direct skin smear and PCR, or a positive result on the direct skin smear and a negative result on PCR. Conclusion: It is clear that the FNA method is not a favorable method for the diagnosis of acute cutaneous leishmaniasis in comparison with the direct skin smear. Since the number of the leishman bodies in FNA is limited, it is better to use this method as a complementary method along with other methods such as culture.