Histopathologic Perspective of Nail Lichen Planus: A 10-year Case Series From a Tertiary Care Center in South India.

Nail involvement is seen in 10% of lichen planus patients, with a subset developing severe destruction of the nail matrix. Nail biopsy is a complex procedure usually done when nails are the only site of involvement. The pathology of nail lichen planus (NLP) has been the subject of very few studies. Most studies refer to the major and minor histopathologic criteria proposed by Hanno et al. This study aims to characterize the histopathologic features of NLP. Twenty five patients of NLP with nail biopsies, diagnosed in the last 10 years were included in the study. Lichen planus was suspected in all patients, and the alternative diagnosis was psoriasis/onychomycosis and melanoma. On histopathology, the common features included acanthosis (88%), lichenoid lymphocytic inflammation (96%), and hypergranulosis (72%). Detachment of epithelium from the subepithelium, a hitherto unreported feature, was noted in 60% of cases. Less common features were lymphocytic exocytosis (48%), melanophages (40%), basal vacuolar alteration (24%), apoptotic keratinocytes (28%), fraying of the nail plate (24%), and spongiosis (20%). Understanding the common and less common histopathologic features and their correlation with clinical findings is essential to diagnose NLP accurately rather than stressing histologic criteria as major/minor, which may lead to the underdiagnosis of cases.