Diagnosis and therapeutic outcomes of biopsy-confirmed Pure Neuritic Leprosy: A two-decade experience

Background

Pure neuritic leprosy (PNL) is a distinct form of leprosy characterized by peripheral nerve involvement without skin lesions. Diagnosis is often delayed, and ‘silent neuritis’ contributes to progressive and irreversible nerve damage. Despite appropriate therapy, many patients develop long-term disability. This study describes the clinical profile, diagnostic patterns, therapeutic outcomes, and predictors of disability in biopsy-confirmed PNL.

Methods

We conducted a retrospective observational cohort study at a tertiary referral centre in South India, enrolling biopsy-confirmed PNL cases from January 2003 to May 2023. Demographic, clinical, electrophysiological, and histopathological data were collected. The primary outcome was the proportion of patients with high disability at follow-up (WHO grade 2). Predictors of disability were identified using multivariate analysis.

Results

Ninety-five patients were included (mean age 43.02 years (SD 15.32); 77% male). Over half (55%) presented 1–5 years after symptom onset. Sensory deficits were most common (80%), followed by foot drop (51%), ulnar claw (38%), and trophic ulcers (25%). Electrophysiology revealed mononeuritis multiplex in 52.6% and axonal polyneuropathy in 22.2%. Nerve biopsy showed borderline tuberculoid pathology in 78% and borderline lepromatous in 15.7%. Notably, 6 patients with mononeuropathy had lepromatous pathology. All patients received multidrug therapy; 41 experienced lepra reactions. Higher severity at treatment initiation was significantly associated with persistent disability.

Conclusions

PNL often presents late, with many patients already experiencing nerve damage. A substantial subset of clinically mononeuritis patients demonstrated lepromatous pathology, emphasizing the need for nerve biopsy in all suspected cases. Early detection and timely treatment may reduce disability burden. These findings highlight critical gaps in current diagnostic strategies and underscore the importance of aggressive early intervention in PNL.