Chronic fungal meningitis secondary to dematiaceous fungi masquerading as tubercular meningitis

Abstract

Cerebral phaeohyphomycosis is a rare cause of central nervous system infection. Even immunocompetent hosts may be affected. To describe the clinical course and challenges in the diagnosis of a patient with cerebral phaeohyphomycosis who was initially mistaken to have tubercular meningitis. A 48-year-old farmer from India presented with chronic headache and intermittent fever. Serial MRIs of brain showed enhancing exudates in basal cisterns, sella, perichiasmatic and cerebellopontine angle region. Cerebrospinal fluid (CSF) study showed lymphocytic pleocytosis (102 to 1000 cells/cu.mm) and elevated protein (47 to 338 mg/dl). Anti-nuclear antibody, anti-neutrophil cytoplasmic antibody and angiotensin converting enzyme levels were normal. GAD65 antibody was inconsistently positive in serum. Cysticercal antibody was detected in CSF. Based on these observations, the differential diagnoses of tubercular vs cysticercal meningitis were considered. He was treated with anti-tubercular therapy, albendazole and steroids. His symptoms persisted despite good compliance. Dural biopsy after two years of illness revealed necrotising granulomas with numerous slender, pauci-septate pigmented fungal hyphae. Dural culture grew Cladophialophora species. ATT and steroids were discontinued and treatment with amphotericin B and voriconazole was initiated. Cladophialophora species, the most frequently isolated species in cerebral phaeohyphomycosis, causes life-threatening brain abscess, meningitis, encephalitis, myelitis or arachnoiditis. The salient feature in our patient is chronic indolent course despite long-term steroid intake without anti-fungal therapy for two years. Diagnosis of cerebral phaeohyphomycosis requires high index of suspicion. CSF and MRI may mimic tubercular meningitis in endemic areas, however hypoglycorrhachia is uncommon. Targeted biopsy clinches the diagnosis.