Tinea Incognito Imitating Pustular Psoriasis in a Psoriatic Patient Following Immunosuppressive Therapy: Case Report...

Tinea incognito is an atypical form of dermatophytosis caused by previous use of topical or systemic immunosuppressive therapy, most often corticosteroids. Modification of the clinical presentation frequently leads to diagnostic delay and misdiagnosis, especially in patients with concomitant chronic inflammatory skin diseases such as psoriasis. We present a narrative review of the literature on tinea incognito in patients with psoriasis during immunosuppressive therapy. We screened 386 abstracts and included 16 comparable case reports focusing on tinea incognito occurring in patients with psoriasis or during antipsoriatic treatment. The review summarizes clinical presentations, diagnostic challenges, and therapeutic approaches reported in the literature. Additionally, we present a clinical case of a 27-year-old man with a long history of plaque psoriasis treated with methotrexate and cyclosporine. The patient developed rapidly progressive skin lesions with pustular features and further deterioration despite systemic antipsoriatic therapy. Initial mycological examinations were negative. Histopathological examination revealed a chronic purulent perifollicular inflammatory process with extension into the subcutaneous tissue. The correct diagnosis was confirmed after a repeat skin biopsy with periodic acid-Schiff and Grocott staining and fungal culture of the skin tissue, which revealed Trichophyton rubrum. The review highlights that clinical features are often nonspecific and may overlap with inflammatory dermatoses. This underscores the need for a high index of clinical suspicion for fungal infection in atypical or refractory psoriatic lesions. It also emphasizes the importance of repeated mycological and histopathological examinations to achieve an accurate diagnosis, avoid inappropriate escalation of immunosuppression, and enable timely antifungal treatment.