An Ulcerating Perineal Rash in an 8-month-old Girl.

1. Nisha Ganesh, MD* 2. Rena Kasick, MD*,† 3. Emily Graham, MD*,†,‡ 1. *The Ohio State University College of Medicine, Columbus, OH 2. †Nationwide Children’s Hospital, Columbus, OH 3. ‡The Ohio State University Wexner Medical Center, Columbus, OH A previously healthy 8-month-old female presents to the emergency department (ED) with diarrhea and an unusual diaper rash. Her symptoms began 6 days prior with fever and congestion. She was initially diagnosed with a viral upper respiratory infection and bilateral otitis media and was prescribed cephalexin by her primary care physician. Two days later, she developed diarrhea and a painful diaper rash. Cephalexin was changed to cefdinir due to concern for antibiotic-induced diarrhea. After 5 days of treatment, antibiotics were discontinued. Before this presentation to the ED, she had been evaluated multiple times in the ED for worsening diaper rash and was prescribed a barrier cream, topical antifungal cream, and mupirocin ointment without improvement. Her medical history includes 1 prior episode of acute otitis media. Her immunizations are up to date. She takes no medications. She lives at home with her mother and father. There have been no known sick contacts, no recent travel, no known insect bites, and no animal exposures aside from the family’s pet dog. Her vital signs on presentation are as follows: temperature, 98.6°F (37°C); heart rate, 160 beats/min; respiratory rate, 40 breaths/min; blood pressure, 100/48 mm Hg; oxygen saturation, 95% on room air. Her parents report that she has had profuse watery diarrhea and decreased urine output, and they describe her behavior as fussy and irritable. Her review of systems is negative for vomiting, blood in the stool, abdominal pain or distension, easy bleeding or bruising, weight loss or inadequate weight gain, recurrent infections, and rashes aside from the current diaper rash. On physical examination, she has multiple large areas of ulceration and necrosis surrounded by halos of erythema in the genitourinary region (Fig 1). Her laboratory studies are significant for blood urea nitrogen of 24 mg/dL (8.6 mmol/L), creatinine of 0.73 mg/dL (55.7 µmol/L), …