Fever and Perianal Erythema in a 5-year-old Boy

A 5-year-old boy with pre–B-cell acute lymphocytic leukemia presents with fever, nausea, vomiting, and decreased oral intake during the past 24 hours. He had a temperature of 102°F (38.9°C) at home and was brought to the hospital due to concern for chemotherapy-induced neutropenia with fever. He had a history of constipation with painful bowel movements and a history of recurrent perianal erythema. At home he takes lactulose, oxycodone, ondansetron, and diphenhydramine as needed along with his chemotherapy regimen. He was last hospitalized 2 weeks earlier for fever and neutropenia and received empirical intravenous (IV) cefepime. At that hospitalization he was noted to have perianal erythema, and a swab of the perianal area was obtained and ordered as a culture for group A streptococcus (GAS). The antigen was negative for GAS, and no GAS was isolated on the culture. A blood culture from that admission was negative. He clinically improved and...