Adjacent Clinicopathological Discordance and Neural Impairment in Multibacillary Borderline Lepromatous Leprosy with Mid-Borderline Histopathology: A Single-Case Study

Abstract

Background: Borderline Hansen disease is an immunologically unstable spectrum in which clinical and histopathological classifications may diverge, and neuropathy often precedes skin lesions, delaying diagnosis.

Objective: To describe a patient with one-step clinicopathological discordance and multi-trunk nerve impairment, and to show how classification should guide therapy.

Methods: Single-case observational study at a tertiary referral hospital in Central Java, Indonesia. Dermatological mapping, motor and sensory nerve scoring, slit-skin smear, and punch biopsy with Fite-Faraco staining were recorded at baseline (T0) and one month (T1) of WHO multibacillary multidrug therapy (MB-MDT). Six- and twelve-month values (T2, T3) are projections.

Results: A 53-year-old man had 8 months of bilateral numbness of the hands and feet and 3 months of generalized, asymmetric infiltrated plaques with punched-out morphology. The left facial, bilateral ulnar, and bilateral common peroneal nerves were impaired without palpable thickening. Slit-skin smear showed a bacterial index (BI) of 3+ and morphological index (MI) of 5.0%; histopathology showed mid-borderline (BB) features with abundant bacilli (Fite-Faraco +++). Clinical synthesis established multibacillary borderline lepromatous (BL) disease. At one month, erythema fell by 41.2%, induration by 43.8%, and the total motor score rose by 16.7%, without leprosy reactions. Modeled 12-month projections indicate a 94.1% fall in erythema, MI 0.0%, and a +66.7% motor score gain.

Conclusion: One-step discordance is compatible with borderline instability and should not alter multibacillary therapy, which should follow the highest clinical and bacteriological severity. Neuropathy without palpable nerve thickening should prompt skin and smear examination.