Porokeratosis and Actinic Keratosis Developing During Phototherapy for Mycosis Fungoides

Summary: Mycosis fungoides (MF) is the most common form of primary cutaneous T-cell lymphoma. It is histopathologically characterized by an epidermotropic infiltration of atypical T-cells and clinically by progression from patches to plaques and eventually tumors. While patients with MF have an increased risk of hematologic malignancies, there is no confirmed elevated risk of skin cancer. Narrowband ultraviolet B light (NB-UVB), a widely used phototherapy for MF, is generally well tolerated. However, rare cases of Bowen’s disease or squamous cell carcinoma following NBUVB treatment have been reported. The simultaneous or sequential occurrence of MF, porokeratosis and actinitic keratosis (AK) is exceedingly rare. We present a case of a patient with MF treated with NB-UVB who developed epidermodysplasia verruciformis, porokeratosis and actinic keratosis, and we explore the potential underlying etiologies.