A Rare Case of De Novo Histoid Leprosy Mimicking Keloids: A Diagnostic Challenge

Abstract

Introduction
Histoid leprosy is an uncommon variant of multibacillary leprosy, and de novo presentation without prior treatment history is extremely rare. This case is unique in that it mimicked keloids, a benign dermatologic condition, leading to potential diagnostic delays. By presenting with nodulo-plaque lesions resembling keloids, this case expands the known clinical spectrum of leprosy and highlights the importance of maintaining a high index of suspicion for leprosy in endemic regions—even when the presentation is atypical. It contributes to the literature by documenting a rare morphological mimic of a neglected tropical disease.
Patient Concerns and Clinical Findings
A 23-year-old male presented to the dermatology OPD with multiple asymptomatic, skin-colored raised lesions over a 6-month period. The lesions began as a single keloid-like plaque on the left upper arm and gradually spread.
Clinical Examination:
Multiple, well-defined, erythematous, hypoesthetic, smooth, firm plaques and nodules on the arms, legs, and posterior trunk
Ulcerated nodules over both elbows
Bilateral ulnar and radial cutaneous nerves moderately thickened, smooth, and non-tender
Investigations:
Slit skin smear: Bacteriological index (BI) 4+, Morphological index (MI) 70%
Histopathology: Free Grenz zone, diffuse lymphohistiocytic infiltrate, foamy macrophages in whorled granulomas
Fite-Faraco stain: Clumps of solid-staining acid-fast bacilli

Diagnosis, Interventions, and Outcome
Diagnosis:
De novo histoid leprosy presenting as keloid-like lesions
Management:
Multidrug therapy for multibacillary leprosy (MDT-MB)
Oral multivitamin (once daily)
Oral calcium + vitamin D3 supplementation (once daily)
Topical fusidic acid 2% cream (applied twice daily over ulcerated lesions)
MCR (microcellular rubber) footwear
Limb care with emphasis on hands and feet protection
Outcome:
Patient continues to be under follow-up with improvement in ulcerated lesions and no new lesions reported post-initiation of MDT.
Conclusion and Key Takeaways
This case underscores the importance of clinical vigilance in diagnosing leprosy, particularly when it presents with atypical morphological features. What appeared to be a simple keloid turned out to be a manifestation of a disabling, chronic infectious disease. In endemic regions, even benign-appearing lesions should prompt a full diagnostic work-up. Early recognition and initiation of treatment remain key to reducing transmission and preventing complications.