Porokeratotic variant of lichen planus or lichen planus with porokeratosis: report of a challenging case

Annular lichenoid diseases have many differential diagnoses. Lichen planus (LP) and porokeratosis could show annular-shaped lesions with a lichenoid tissue pattern infiltration, but typical cornoid lamella formation is mainly in favor of porokeratosis. We present a 57-year-old man with papulovesicular and annular lesions on the shins with an exophytic lesion of left great toe nail. Papular lesions showed classic histopathology of LP, but annular lesions revealed imperfect cornoid lamella formation that could be seen in the porokeratotic variant of LP. Nail bed biopsy showed in-situ squamous cell carcinoma and so distal phalangeal amputation was performed. Our patient had no good response to topical and systemic steroid, but he had moderate improvement with oral retinoid. We think that our case had different types of LP including classic, bullous and porokeratotic variants which is a rare association.