A 39-year-old woman presented with generalized seizures. Clinical examination findings were normal. Brain computed tomography showed 2 hyperdense subcortical lesions in the right temporal and frontal lobes. Enhancement was seen in the temporal lesion after contrast injection. Magnetic resonance imaging patterns were as follows: the temporal lesion was slightly hypointense on the T1-weighted sequence, clearly enhanced by gadolinium administration (Figure 1A), and hypointense surrounded by a hyperintense signal on the T2-weighted sequence; the frontal lesion was slightly hypointense on the T1-weighted sequence, enhanced after gadolinium injection (Figure 1A), and mixed isointense/hyperintense on the T2-weighted sequence. Findings from the cerebral spinal fluid examination, cerebral angiography, mammography, and thoracic, abdominal, and pelvic computed tomography were normal. A multifocal brain tumor was suspected. Carbamazepine therapy was started. Four years later, the signal characteristics of the frontal lesion had changed and it was seen as a central hypointensity surrounded by a hyperintense signal on the T2-weighted sequence (Figure 1B). A new lesion close to the Monro foramen was visualized only after gadolinium injection (Figure 1C). A frontal lesion biopsy was noncontributive. Another 4 years later, depression and minor cognitive impairment occurred. All 3 lesions showed hyperintense components on unenhanced T1-weighted sequences and increased size after gadolinium injection (Figure 1D). A new biopsy of the temporal lesion found extracellular deposits of amorphous acidophil eosinophilic material, staining positive with Congo red (Figure 2), with apple-green birefringence under polarized light, signaling amyloid deposits. Immunohistochemical stains showed λ light-chain predominance. Repeated immunoelectrophoresis, echocardiography, electromyography, and multiple biopsies (salivary gland, skin, nerve, muscle, bone marrow, rectosigmoid, stomach, and duodenum) did not reveal any systemic amyloidosis. Primary brain amyloidoma was diagnosed. Seventeen years after onset, clinical evaluation findings remained unchanged and all the lesions showed a further increase in size on gadolinium-enhanced T1-weighted sequences.