A Rare Case of Cerebral Amyloidoma Mimicking a Hemorrhagic Malignant Central Nervous System Neoplasm.

Cerebral amyloidoma is a rare form of amyloidosis with a localized tumor like an amyloid deposition in the brain composed of insoluble fibrillary protein with cross beta-sheet conformation. Its usual presentation includes vision loss, seizures, behavioral changes, cognitive decline, and recurrent headaches. It has a benign course with a slow progression, and it is not associated with dissemination. We report a case of a 65-year-old Caucasian woman who presented with symptoms of progressively worsening cognitive dysfunction of six months' duration. From CT of the brain, it was found that she had a right frontal and left parietal hemorrhagic mass with a large amount of vasogenic edema and a midline shift. MRI showed heterogeneously enhancing hemorrhagic mass of 5.2 cm x 2.6 cm x 3.6 cm in size, with a satellite lesion. Initially, this was suspected to be a high-grade glioma vs. metastatic hemorrhagic lesions. She underwent stereotactic biopsy of the mass, and histopathology was consistent with cerebral amyloidoma with marked IgA lambda plasma cell differentiation. She did not have any evidence of systemic amyloidosis, and therefore, she is being clinically observed with a regular follow-up and annual CT surveillance. She has remained stable over the past two years, although she has residual cognitive dysfunction. Cerebral amyloidoma can mimic malignant central nervous system (CNS) neoplasms and should be considered as a differential of any single or multiple mass lesions occurring in the white matter region of the brain with a characteristic appearance of "hyperdense lesions" on CT. It is a benign disease with no metastatic potential that usually resolves entirely after resection.