Review Question - QID 109822

A 55-year-old man presents to the emergency room with a skin lesion. It has persisted for several days without improvement. The patient has a medical history of alcohol abuse, intravenous drug abuse, diabetes, human immunodeficiency virus infection, and depression. He last used heroin 3 days ago and has been drinking 4-7 alcoholic drinks per day. He does not follow with a physician regularly. His temperature is 99.5°F (37.5°C), blood pressure is 157/98 mmHg, pulse is 100/min, respirations are 14/min, and oxygen saturation is 98% on room air. Cardiopulmonary exam is notable for a systolic murmur heard along the left sternal border. Dermatologic exam is notable for the finding in Figure A. The patient's abdominal exam and neurological exam are within normal limits. Which of the following is the most likely diagnosis?