Primary amyloidoma of the brain parenchyma.

Amyloidoma can occur within the brain parenchyma. Periventricular amyloidomas developed in a man aged 69 years as gadolinium-enhancing lesions on magnetic resonance imaging. The lesions were composed of amyloid AL lambda with congophilia resistant to potassium permanganate. There was no evidence of systemic amyloidosis or an underlying inflammatory or neoplastic disorder.