Diagnosis of Cutaneous Leishmaniasis in Colombia: the Sampling Site within Lesions Influences the Sensitivity of Parasitologic Diagnosis

Abstract

Parasitologic confirmation of cutaneous leishmaniasis is obligatory before chemotherapy can be considered. Direct microscopic examination of scrapings taken from indurated borders of ulcers has been routinely used as primary method of diagnosis. In this report we compared the sensitivity of examination of dermal scrapings taken from the bottoms of ulcers (BDS) with that of dermal scrapings taken from indurated active margins of lesions (MDS) in a total of 115 patients. The sensitivities of the microscopic examination were 90.4 and 78.3% for BDS and MDS samples, respectively. When the PCR method was used with a group of 40 patients, we also observed a higher sensitivity when BDS samples were examined (80.8% in BDS samples versus 57.7% in MDS samples). The improvement of the diagnostic sensitivity in the BDS samples appears to be related to the higher parasite load and more easily detectable morphology of amastigotes in the centers of the ulcers. Other parasitologic diagnostic methods, such as culture and histopathologic examination of biopsies, are less sensitive (67.5 and 64.3%, respectively). Aspirate culture, however, was shown to be the most sensitive method for the diagnosis of patients with chronic ulcers. When microscopic examinations of both MDS and BDS samples are combined, the sensitivity of diagnosis may rise up to 94%. We therefore recommend this method as a primary routine procedure for diagnosis of cutaneous leishmaniasis.

American cutaneous leishmaniasis in infancy and childhood

“…51 Fine needle aspiration has also proven to be a promising diagnostic method for culturing and identification (being also easier and less painful to perform than a biopsy for children) but requires experienced hands and exhibits a variable grade of sensitivity. 13,52 Tissue samples should be taken from the edge of the lesions where the parasite activity is greater, 53,54 and noble anatomic areas such as the face should be respected; routine stains as well as immunoperoxidase stains usually help to reveal the amastigotes well. 25 Culture is performed in special media (Novy- Detection of parasite DNA in tissue specimens is usually most sensitive in diagnosis and can even allow molecular characterization to a species level, but due to scarce economical resources, it is difficult to practice in developing countries.…”

Cutaneous leishmaniasis: advances in disease pathogenesis, diagnostics and therapeutics

“…The sampling site within lesions influences the sensitivity of parasitological diagnosis; for maximum sensitivity, incisional biopsies should be taken from the active edge of skin lesions rather than from the centre or the base of an ulcer. 10 A minimum of two biopsies are necessary: one fixed in formalin for histopathology and the other sent as fresh tissue in saline-soaked gauze for all other investigations. Species identification is critical as it determines the clinical course, prognosis and choice of treatment, and until the recent development of molecular methods, it was only possible through isoenzyme analysis of Leishmania culture.…”

Delay in diagnosis: trauma‐ and coinfection‐related cutaneous leishmaniasis because of Leishmania guyanensis infection

“…56 False-negative results with PCR methods have been ascribed to factors such as the stage of the lesion, uneven distribution of amastigotes in the tissue sections and what part of the ulcer was sampled. 54,57 Another utility of PCR method is the ability to identify specific Leishmania species. 55,58 Identification of Leishmania species has clinical importance as certain species are resistant to standard therapy, pentavalent antimonials.…”