Neutrophilic dermatoses are characterized histologically by a sterile infiltration of neutrophils throughout the dermis. The condition may affect various internal organs, notably the lungs, the digestive tract, and the joints, whereas muscle impairment is considered to be extremely rare. We describe the case of a patient with pyoderma gangrenosum in whom severe sterile neutrophilic myositis developed as the first manifestation of an acute myelogenous leukemia.