Evaluating CD1a Immunohistochemistry for Tegumentary Leishmaniasis Diagnosis in the New World: A Focus on Colombia.

Introduction: Leishmaniasis, a chronic vector-borne disease caused by parasites of the genus Leishmania , presents diagnostic challenges. Conventional diagnostic methods struggle with accurate visualization of these parasites. Immunostaining with CD1a has demonstrated effectiveness in visualizing Leishmania parasites, particularly in the Old World. However, the application of CD1a immunostaining in Colombian leishmaniasis remains unexplored.

Objective: To determine the utility of CD1a as an immunomarker in detecting chronic forms of tegumentary leishmaniasis.

Materials and methods: This proof-of-concept study involved 48 paraffin-embedded samples categorized into 3 groups: moderate-to-high parasite load (n = 15), low load (n = 15), and chronic granulomatous inflammation (n = 13); 5 samples diagnosed with cutaneous histoplasmosis. These samples were stained with the immunomarker CD1a clone EP3622 for comparative analysis. In addition, CD1a immunohistochemistry was compared with 18S rDNA qPCR and hematoxylin-eosin staining to evaluate its performance in relation to these established methods.

Results: CD1a immunohistochemistry was positive in 46.51% of the samples evaluated. This immunomarker showed lower sensitivity and negative predictive value than 18S rDNA qPCR and hematoxylin-eosin staining; specificity and negative predictive value were consistent. ROC indicated inferior discrimination for leishmaniasis compared with 18 s rDNA qPCR and hematoxylin-eosin staining.

Conclusions: Immunohistochemistry for CD1a could be a diagnostic support in the detection of chronic forms of tegumentary leishmaniasis.