The Role of Histopathology and Immunohistochemistry in the Diagnosis of Cutaneous Leishmaniasis Without “Discernible” Leishman–Donovan Bodies

Background: Histopathology plays an important role in the diagnosis of cutaneous leishmaniasis (CL) but Leishman–Donovan (LD) bodies may not always be discernible. Recently, anti–CD1a antibody (Ab), clone MTB1, was found to decorate LD bodies immunohistochemically. Objective: Can histopathology without discernible LD bodies be used to diagnose CL, and can immunohistochemistry using anti–CD1a Ab, clone MTB1, detect LD bodies in these cases. Methods: Suspected CL lesions were studied histopathologically and immunohistochemically, and the patients' clinical files were reviewed. Results: Of the 196 patients with suspected CL, direct smear demonstrated LD bodies in 50 (25.5%). Of the remaining 146 patients, 118 underwent biopsy. In 56 (47.5%) patients, the hematoxylin-eosin–stained sections revealed LD bodies. In 47 (39.8%) patients, LD bodies were not discerned but the histopathology demonstrated histiocytic infiltrates with varying numbers of plasma cells along with other inflammatory cells, and negative Ziehl–Neelsen and periodic acid–Schiff stains. This pattern was termed "histopathology consistent with leishmaniasis." The history, clinical findings, and response to anti–leishmania therapy supported the diagnosis of CL in all of them, and immunostains for CD1a, clone MTB1, detected LD bodies in 11 (23.4%) of these 47 patients. Conclusions: "Histopathology consistent with CL" along with appropriate clinical findings supports the diagnosis of CL in an endemic area, and immunostains with CD1a Ab, clone MTB1, may help in the minority of the cases.

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