Altered Mental Status and First-Time Seizure in Teen With a Subacute Inguinal Mass

A healthy 13-year-old boy who resides in rural Vermont presented after witnessed, generalized seizure-like activity for approximately 2 minutes. He had been well until the development of right inguinal pain and rash 2 weeks before presentation, which had progressed to a 5-cm irregular, red, tender, and raised area that was unresponsive to 5 days of cephalexin. At the time of presentation, he was afebrile and hemodynamically stable and only responsive to localized stimuli. Initial laboratory evaluation, toxicology screening, and computed tomography of the head were all unremarkable. Ultrasonography of the inguinal lesion showed an abscess with subcutaneous edema and reactive lymphadenopathy. He did not have evidence of stroke or status epilepticus. Because of his persistent altered mental status, the patient was admitted to the pediatric intensive care unit, and pediatric infectious disease was consulted. A detailed history revealed he had extensive recent animal exposures that included bear, deer, dogs, chickens, and kittens. Cerebrospinal fluid (CSF) analysis showed 5 leukocytes (26% polymorphonuclear leukocyte), normal glucose, and slightly elevated protein. Video electroencephalogram demonstrated bilateral cerebral dysfunction, whereas the brain magnetic resonance imaging and magnetic resonance venogram scan results were normal. CSF culture and polymerase chain reaction results for bacterial and viral pathogens were negative. Fluid collected from the inguinal lesion showed neutrophils but no organisms. The following discussion describes this patient's full course, differential diagnoses, diagnostic workup with clinical reasoning, and final diagnosis.