Hypopigmented Skin Lesions with Doubtful/Minimal Sensory Impairment: A Histopathology-Based Analysis.

Background: Cardinal criteria proposed by the World Health Organisation (WHO) lack sensitivity to diagnose indeterminate leprosy. Aims: To estimate the frequency of hypopigmented skin lesions with doubtful/minimal sensory impairment showing histopathology features of indeterminate leprosy. To compare between the histopathology findings noted in specimens showing features suggestive of indeterminate leprosy and those showing a non-specific dermatitis pattern. Materials and Methods: Data on patients who attended our department with hypopigmented patches with doubtful/minimal sensory impairment from January 2018 to December 2019 and who underwent a skin biopsy were collected. A pathologist blinded to the clinical findings reviewed the histopathology specimens using a pre-set questionnaire. Results: We studied sixteen biopsy specimens from 14 patients. Eight specimens (50%) showed histopathology suggestive of indeterminate leprosy and the remaining eight showed a non-specific dermatitis pattern. A higher percentage of patients with indeterminate pattern showed mast cells (87.5% vs 25%) and fibrosis around nerve twig or sweat duct (75% vs 12.5%) when compared to those who showed a non-specific dermatitis pattern. Limitations: Small sample size and retrospective study design were the limitations. Conclusions: We found histopathology features of indeterminate leprosy in 50% of the skin biopsy specimens from hypopigmented lesions with doubtful/minimal sensory impairment. The present study highlights the need to improve the diagnostic definition of indeterminate leprosy.