Pseudo-subarachnoid hemorrhage in cryptococcal meningitis: MRI findings and pathological study

Abstract

A pseudo-subarachnoid hemorrhage (pseudo-SAH) is a brain computed tomography (CT) finding that is seen as high-density areas along the basal cisterns, the sylvian vallecula/fissure, the tentorium cerebella, or the cortical sulci, although no SAH is found upon lumbar puncture or at autopsy. There is one report of cryptococcal meningitis presenting as pseudo-SAH, but the explanatory pathology is unknown. A 68-year-old woman with headache, fever, decreased hearing, and decreased vision was admitted to our hospital. Cerebrospinal fluid India ink staining was positive, and culture yielded Cryptococcus neoformans. Cryptococcus meningitis was diagnosed. Head CT and magnetic resonance imaging (MRI) showed no abnormality upon admission, but 1 month later, head CT showed iso- to high-density areas within the sulci, and fluid-attenuated inversion recovery MRI showed high signal intensity within the convexity sulci resembling an SAH. These areas were enhanced by gadolinium on T1-weighted images. Lumber puncture produced no evidence of bleeding. Biopsy of the left frontal lobe sulci was performed, and histopathological study revealed inflammation and granulation with capsules of C. neoformans. The inflammation and granulation at the convexity sulci induced by the C. neoformans infection explained the pseudo-SAH in this case. Physicians should be aware that cryptococcal meningitis-induced inflammation and granulation at the sulci can present as pseudo-SAH on CT and MRI.