Rash, Diaphoresis, Anorexia, and Loss of Motor Skills in a 10-month-old Boy

Presentation

A previously well 10-month-old boy presents with a 1-month history of a papular rash with interdigital desquamation, diaphoresis, and anorexia. These symptoms were preceded by a 3-day febrile illness with otitis media. He had weight loss of 1 kg and lost the ability to crawl and cruise during this period.

The patient’s medical history was unremarkable. He was born at 41 weeks’ gestation by spontaneous vaginal delivery after an uneventful pregnancy. Developmentally he was previously sitting, cruising, and babbling. There were no known sick contacts. The family had traveled to Mexico 4 months before presentation, but the patient was well on return.

On physical examination the boy’s temperature is 97°F (36.1°C), respiratory rate is 48 breaths/min, heart rate is 136 beats/min, and blood pressure is 111/63 mm Hg. His weight is 7.9 kg (5th percentile) and length is 72 cm (11th percentile). He is alert but irritable and unable to sit without tripoding. He has no cervical adenopathy and no oral changes. He is diaphoretic. He has a slight head lag with overall decreased tone and deep tendon reflexes in the upper and lower extremities that are difficult to elicit. There is an erythematous papular rash on the trunk, upper arms, buttocks, thighs, and dorsal hands, with interdigital desquamation.

Laboratory testing from the emergency department reveals normal complete blood cell and differential counts and normal levels of electrolytes, liver enzymes, creatinine, and C-reactive protein. He is admitted to the hospital for further diagnostic evaluation and nutritional …