Lichen planus mimicking recalcitrant ulcerative psoriasis: when is it time to biopsy?

Hypertrophic lichen planus (LP), also known as LP verrucosus, is a rare disorder that presents as verrucous plaques, typically on the lower extremities and ankles. This variant differs from the common presentation of LP, which appears as flat, polygonal, pink-purple papules spread diffusely on the flexor wrists, trunk, shins, and dorsal aspects of the feet, frequently involving the oral mucosa. Clinically, hypertrophic LP can be confused with psoriasis and usually does not respond to therapy with biologics. We present a case of hypertrophic LP in a 42-year-old woman who had been treated extensively for psoriasis. Although the morphology and location of the hyperkeratotic plaques mimicked psoriasis, biopsy results exhibited characteristic features of hypertrophic LP, and the lesions responded to treatment with acitretin, clobetasol propionate ointment, hydroxychloroquine, and simple wound care. The hypertrophic variant of LP can be extremely challenging to differentiate from psoriasis. Physicians who treat patients with scaly plaques should think beyond psoriasis and consider the hypertrophic variant of LP as a potential diagnosis.