Intracerebral amyloidoma: case report and review of the literature.

Intracerebral amyloidoma (ICA) is a type of monoclonal immunoglobulin deposition disease (MIDD) which is accompanied by an overexpression and fibrillary assembly of monoclonal light chains, ultimately leading to nodular deposits of light chains in the form of amyloid light chain (AL-amyloid). The diagnosis is made by the histological demonstration of intracerebral masses harboring the classical staining and birefringence features of amyloid. We aim to report a case of ICA and review histological features of previous cases. A 51-year-old man with epilepsy and cognitive decline was admitted for epileptic seizures. A brain magnetic resonance imaging (MRI) disclosed periventricular enhancing lesions, hypointense on T1 and heterogeneous on T2-weighted images. A brain stereotactic biopsy was performed. The neuropathological examination revealed several congophilic nodules, allowing the diagnosis of ICA. The immunohistochemical study was positive for transthyretin (TTR), and both lambda and kappa immunoglobulin light chains. No inflammatory infiltrates were seen. Although a plasma cell clone may play a major role in the etiopathogeny of ICA, plasma cells were scarce or even absent when reviewing histological reports. ICA has a poorly understood patgogenesis. ICA may simulate malignant neoplasms, hence the need for a definite histological diagnosis.