Diagnostic challenges of undiagnosed mycosis fungoides initially treated as chronic eczema: A retrospective study from Kosovo (2016–2024)

Abstract

ABSTRACT Background: Mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, often presents nonspecific eczematous or psoriasiform lesions, which frequently results in diagnostic delay. Objectives: To evaluate the clinical features, diagnostic challenges, and misclassification patterns of MF patients who were initially treated as chronic eczema in Kosovo. Methods: A retrospective study was conducted including 16 patients diagnosed with MF between 2016 and 2024 at the University Clinical Center of Kosovo. All diagnoses were confirmed histopathologically and immunohistochemically. Demographic data, duration before diagnosis, clinical features, and outcomes were analyzed. Results: Among 16 patients (14 males, 2 females; mean age 58.2 ± 6.4 years), the mean diagnostic delay was 12.6 ± 7.4 months (range 6–24). All patients had previously been treated as chronic eczema; most had received prolonged topical corticosteroids. One patient progressed to tumor-stage MF and died, while another reported a family history of chronic lymphocytic leukemia. Immunohistochemical analysis confirmed a predominant CD3+/CD4+ phenotype with clonal TCR expression. Conclusions: MF continues to be underrecognized in its early phases, often mistaken for eczema. Persistent or treatment-resistant dermatitis should prompt early biopsy and clinicopathologic correlation to avoid diagnostic delay and improve prognosis. Key words: Mycosis fungoides, Diagnosis, Clinical challenge, Immunohistochemistry