Ecthyma gangrenosum is an infection of the skin typically caused by Pseudomonas aeruginosa. It is often seen in immunocompromised patients such as those with neutropenia. Ecthyma gangrenosum presents as a round or oval lesion, 1.0 to 15 cm in diameter, with a halo of erythema. A necrotic center is usually present with a surrounding erythematous edge, representing where the organism invaded blood vessels and caused infarctions. These ulcerative lesions are single or multiple and heal with scar formation, although sepsis resulting from other Gram-negative bacteria can also cause this condition.