Abstract
Porokeratosis is an abnormal disease of keratinization of epidermis. It is clinically characterized by margins covered with keratin layer and it typically has an atrophied macule with a protruded, circular form. Histopathologically, it shows the findings of cornoid lamella. Risk factors for its development include organ transplantation, long-term use of corticosteroids, immunocompromised status, including AIDS, and exposure to ultraviolet light. We herein report a case of atypical porokeratosis in a 38-year-old man who developed porokeratosis involving multiple sites following bone marrow transplantation for myelodysplastic syndrome.