We present the case of a 1-year-old healthy boy who was taking oral antibiotics for an otitis media and then developed an erythematous penile lesion that rapidly became ulcerated. He was admitted to the hospital for further diagnostic studies and intravenous therapy, and his wound culture grew Pseudomonas aeruginosa, consistent with the diagnosis of ecthyma gangrenosum. Serial blood counts also demonstrated a progressive neutropenia, and an immunodeficiency evaluation resulted in the diagnosis of autoimmune neutropenia of childhood. This case illustrates the importance of culturing wounds and the need for clinicians to recognize the characteristic features of ecthyma gangrenosum, to initiate appropriate antipseudomonal antibiotic therapy empirically, and to evaluate for a possible immunodeficiency, even in the apparently healthy child.