Evaluation of diagnosis of cutaneous leishmaniasis by direct smear, culture and histopathology

OBJECTIVE: Definite diagnosis of cutaneous leishmaniasis is based on the isolation of the causative organism by smear and culture or its identification in tissue section. This study was conducted to evaluate the efficacy of different sampling techniques. These techniques are tissue sampling with dental broach, slit scrape method, aspiration of the lesion edge and biopsies.

METHODS: This study was carried out in the Department of Dermatology, Baghdad Teaching Hospital, Baghdad, Iraq. Sixty patients with cutaneous leishmaniasis were seen, 33 females and 27 males with a mean age of 15.7 years and the mean duration of the lesions was 8-weeks. The total number of lesions was 167, 60% ulcerative and 40% nodular, 40% of patients had single lesion, while 60% had multiple lesions, and the highest number being 11 lesions. Smears and cultures were carried out in all patients using different sampling techniques. Biopsies were taken from 20 patients.

RESULTS: It was found that tissue sampling using dental broach was better than the other smearing techniques. It was positive in 71.5% while culture on Nicolle-Novy-MacNeal media was positive in 80% of cases and these figures were much higher in comparison to other published studies. The morphology of LD bodies (amastigotes) in smears was mainly spindle shape, other morphological forms like barrel, safety pin and umbrella like were noticed, while the morphology in histopathological sections were rounded with a nucleus and kinetoplast. However, in some sections spindle shape form similar to smear morphology were detected. LD bodies were seen in histopathological sections in 30% of patients. Other histopathological features were mainly abundance of lymphocytes and plasma cells in the wet ulcerative lesions while in dry nodular types there was a tendency to form granuloma with less lymphocytes and scanty plasma cells.

CONCLUSION: Tissue sampling using dental broach appeared to be more efficient than other sampling techniques used in this study. Histopathological sections have identified the focal presence of the parasites. Thus, multiple site samples from the edge of the lesions are needed.