Pembrolizumab-associated exacerbation of lichen planopilaris in a patient with metastatic melanoma

LPP is an underrecognized follicular irAE. The timing, clinical course, and histopathologic findings suggest pembrolizumab-induced exacerbation. Causality was assessed using the Naranjo Algorithm, with a score of 6, indicating a probable adverse drug reaction. This case reinforces the importance of early recognition and tailored dermatologic care in patients receiving ICI therapy.