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Abstract

Verrucous psoriasis is a rare and underrecognized variant of psoriasis characterized by verrucous, hyperkeratotic plaques and a challenging histopathologic profile. We present the case of a man in his 30s with longstanding plaque psoriasis and psoriatic arthritis who developed foul-smelling, verrucous plaques on the lower extremities after poor adherence to biologic therapy. Biopsies of the lesions revealed pseudoepitheliomatous hyperplasia, marked acanthosis, neutrophilic parakeratosis, and epithelial buttressing. Fungal organisms were excluded via negative PAS and GMS stains. The absence of koilocytosis, mucosal involvement, and direct immunofluorescence findings further supported the diagnosis of verrucous psoriasis.

Although fewer than 30 cases have been reported in the literature (1), this condition can closely mimic tinea corporis, pemphigus vegetans, pemphigus foliaceus, and verruca vulgaris both clinically and histologically (2–5). Distinguishing features include the absence of fungal elements, lack of autoimmune antibody markers, and presence of psoriasiform histologic changes such as Munro microabscesses and epidermal buttressing (1,3).

The patient was started on topical and systemic corticosteroids, later transitioning to methotrexate and ixekizumab, with gradual improvement. Verrucous psoriasis tends to have a chronic, relapsing course and can cause significant morbidity. This case highlights the importance of recognizing its histopathologic features and maintaining clinical suspicion in patients with atypical, refractory psoriatic lesions. Early diagnosis can guide appropriate systemic therapy and avoid misdiagnosis with infectious or autoimmune mimickers (1–5).