Atypical Presentation of Borderline Tuberculoid (BT) Leprosy in an Immunocompetent Adult – A Case Report

Abstract

Leprosy is a chronic and progressive granulomatous disease that primarily affects the skin and peripheral
nerves and is caused by the bacterium Mycobacterium leprae. Despite its long history with humans, its varied
presentation continues to baffle clinicians. However, clinicians may miss many cases due to decreased
clinical suspicion of leprosy and atypical case presentations. We present an unusual case of borderline
tuberculoid leprosy, which presented as chronic skin ulcers with no associated anaesthetic skin patches,
peripheral nerve thickness and neuropathy, mimicking cutaneous leishmaniasis. This case report highlights
atypical presentations of borderline tuberculoid leprosy that clinicians may miss without a high index of
suspicion and or skin biopsy.

A 54-year-old male trader presented with a 2-year history of a chronic ulcer on the dorsum of his right hand and
an 8-month history of a similar ulcer on his nose. Both lesions began as painless, non-pruritic swellings.
Examination revealed a 12 cm x 11 cm ulcer on the right hand and a 7 cm x 5 cm ulcer on the nose. No loss of
sensation or nerve enlargement was detected. Routine investigations, including complete blood count, renal
function test and HIV screening, were negative. A slit skin smear revealed acid-fast bacilli, and a skin biopsy
suggested BT leprosy. There was a remarkable improvement in symptoms after multibacillary anti-leprosy
treatment.

Ulceration is an unusual presentation of borderline tuberculoid leprosy. This case highlights the importance of
maintaining a high index of suspicion and the role of skin biopsy in the prompt diagnosis and treatment of
similar cases.

Atypical presentation, Borderline tuberculoid, Leprosy, Atrophic ulcers