Histopathological study of post kala-azar dermal leishmaniasis and its importance for diagnosis in a peripheral tertiary institution

Introduction: Post kala-azar dermal leishmaniasis (PKDL) is a cutaneous complication of treated or subclinical visceral leishmaniasis. For confirmation, detection of Leishman-Donovan body (LDB) in slit skin smear (SSS) is needed. But it reveals a very low positivity. Since other confirmatory investigations are very costly, we studied the histopathological method as one of the accurate in the diagnosis of PKDL. Materials and Methods: We enrolled all suspected PKDL cases (n-24) of different forms within the specified period of one year. Clinically, 5 patients had hypopigmented macular lesions, 7 patients had papules, nodules or plaque lesions and 12 patients had combination lesions. All the patients were investigated with ELISA for rK39 antibody test and SSS for LDB. We had done skin biopsy from the lesions of all cases and stained with Haematoxillin and Eosin for histopathological examination. The tissues were also stained with Geimsa and Fite Faracco stain for better accuracy. Results: We collected 36 biopsy materials from 24 patients. Among 36 samples, 17 samples were of macular lesions and 19 samples were from papule, nodule or plaque. There were sparse lymphohistiocytic infiltrate with a few plasma cells in superficial perivascular locations in macular lesions. In papule, nodule or plaque lesions, the lymphohistiocytic and lymphoplasmacytic infiltrates were in perivascular and periappendegeal locations and extended upto mid dermis. The infiltrates were moderate to heavy according to type of elevated lesion. In some cases, the infiltrates were found in whole dermis and some formed nodular aggregate. Presence of plasma cells and hyalinization of dermal collagen were the important features in PKDL histopathology. Conclusion: The different histopathological patterns of PKDL cases have an immense value to diagnose the case correctly.