Chronic Meningitis by Histoplasma Capsulatum in Immunocompetent Patients: A Diagnostic Challenge (P2.327)

Abstract

OBJECTIVE: To report four cases of isolated lymphocytic chronic meningitis (LCM) in immunocompetent individuals caused by Histoplasma capsulatum, emphasizing the difficult diagnosis and the variable clinical deterioration. BACKGROUND: Chronic meningitis encompasses a heterogeneous group of etiologies. Rarely, histoplasmosis may arise as an isolated neurological syndrome in immunocompetent hosts without evidence of general dissemination. This is a challenging diagnosis, and a high index of suspicion is required from practicing neurologists. METHODS: Description of cases from a tertiary hospital in southeastern Brazil. RESULTS: Four immunocompetent patients who lived in urban areas had chronic meningitis evolving insidiously over 02, 05, 13 and 21 years. Cerebrospinal fluid (CSF) showed lymphocytic pleocytosis (5-222/mm³, reference value [RV] ≤ 3/mm³), reduced glucose (26-50 mg/dL, RV 2/3 of blood glucose) and increased protein (103-247 mg/dL, RV ≤ 42/mg/dL) and ADA (9-32,6 U/L, RV ≤ 9 U/L), with negative bacterial and fungal cultures. Two patients had antibodies against T. sollium in the CSF. Brain MRI revealed hydrocephalus requiring ventriculoperitoneal shunt placement in three of them. One patient had parenchymal spinal cord injury that began 14 years after disease onset, and multiple brain lesions approximately one month before his death. Along disease course, they were treated unsuccessfully for neurocysticercosis and tuberculosis meningitis. All patients ultimately became steroid-dependent for symptom relief. Definite diagnoses came through immunodiffusion analyses of the CSF in three patients and only at necropsy in the other. Two survivors underwent therapy with amphotericin B. The other one developed marrow aplasia secondary to this medication; he was treated with fluconazole as monotherapy with good response. CONCLUSIONS: Pure meningeal histoplasmosis in immunocompetent patients is unusual. Such diagnosis is hindered by technical limitations and absence of classic systemic involvement. The CSF abnormalities are similar to those found in cysticercosis, tuberculosis and other fungal meningitis. Thus, histoplasmosis should be included in the differential diagnosis of LCM especially in those patients unresponsive to the usual treatment regimens.

Disclosure: Dr. Silva has nothing to disclose. Dr. Martinez has nothing to disclose. Dr. Franca, Jr. has nothing to disclose. Dr. Nucci has nothing to disclose. Dr. Penalva de Oliveira has received personal compensation for activities with Abbott, Bristol-Myers Squibb Co. as a consultant, and Abbott, and GlaxoSmithKline Inc. as a speaker.