Acanthamoeba meningoencephalitis presenting as neuropsychiatric lupus in a pediatric patient.

We present the case of a 16-year-old patient with systemic lupus erythematosus who presented with altered mental status and regressive behaviour. She was worked up and empirically treated for common and opportunistic infectious agents. All work-up was negative and after an extensive course of antibiotics she was treated for neuropsychiatric lupus with cytoxan. She initially responded, but this was short-lived and she eventually became comatose and passed away. On brain biopsy she was found to have numerous trophozoites with round nucleus, prominent nucleolus and thin nuclear membrane. Methenamine silver stain showed encysted amoeba, corresponding with a diagnosis of acanthamoeba meningoencephalitis. Making the diagnosis of acanthamoeba meningoencephalitis requires a high degree of suspicion. Specific serum antibodies may not be a reliable measure in immunocompromised patients and trophozoites in CSF can be confused with monocytes. Brain biopsy may be required to make a definitive diagnosis. It is important for clinicians treating immunocompromised patients to keep this agent in mind in an immunocompromised patient with neurological manifestations. Acanthamoeba infections have only been reported in a small handful of patients and, to our knowledge, this is the first reported case in the United States.