A previously healthy, 4-year-old female with unusual skin lesions and mouth sores

Stevens-Johnson syndrome (Figure 3) is a type IV, or delayed hypersensitivity reaction, triggered by drugs such as sulfa or infections such as Mycoplasma. Ecthyma gangrenosum is almost always seen in the face of severe underlying immune deficiency, such as in patients on chemotherapy for cancer, and it is by far most commonly a result of Pseudomonas aeruginosa sepsis, with septic emboli causing necrotic vasculitis. James H. Brien, DO, is with the department of infectious diseases at McLane Children's Hospital, Baylor Scott & White Health, Texas A&M College of Medicine in Temple, Texas.