Nodular post-kala-azar dermal leishmaniasis: a distinct histopathological entity

Area of Science:

• Dermatology
• Parasitology
• Pathology

Background:

• Post-kala-azar dermal leishmaniasis (PKDL) is an infrequent complication following treatment for visceral leishmaniasis.
• Diagnosing PKDL can be challenging, especially in non-endemic regions, due to subtle clinical signs that mimic other conditions like lepromatous leprosy.
• The histopathology of PKDL, particularly nodular lesions, has been underexplored.

Purpose of the Study:

• To describe the histopathological features of nodular lesions in post-kala-azar dermal leishmaniasis (PKDL).
• To evaluate the diagnostic utility of these histopathological findings in a non-endemic setting.

Main Methods:

• Retrospective analysis of 26 skin biopsies from patients with nodular PKDL over 8 years.
• Detailed light microscopic examination of biopsy specimens.
• Assessment of specific histological features including epidermal changes, inflammatory infiltrate, follicular involvement, vascular changes, and collagen alterations.
• Fite stain for acid-fast bacilli was also performed.

Main Results:

• All biopsies exhibited consistent light microscopic features.
• Characteristic findings included a dense lymphohistiocytic infiltrate below an atrophic epidermis.
• Pronounced follicular plugging, vascular hyalinization, and collagen changes were observed.
• Fite stain was consistently negative.

Conclusions:

• The described histopathological features are highly characteristic of nodular PKDL.
• These findings enable a definitive diagnosis of PKDL, even when Leishman-Donovan bodies are not detectable.
• Histopathology is a crucial tool for diagnosing PKDL in non-endemic areas.