Baehring J: MR spectroscopy in the diagnosis of cerebral amyloid angiopathy presenting as a brain tumor

Summary: We present two cases of focal, tumefactive, masslike lesions of diffuse cerebral amyloid angiopathy (CAA) that presented as areas of increased signal intensity on long TR sequences without contrast enhancement or restricted diffusion. MR spectroscopy revealed normal me-tabolite ratios and unremarkable spectra. Pathologic tissue showed CAA and CAA with angitis of the CNS. Tumefactive CAA is a rare condition, and we describe its characteristics at MR spectroscopy and diffusion-weighted imaging. Primary deposition of amyloid in the brain can take the form of senile plaques as in Alzheimer disease, as focal masslike deposition with sparing of the remain-der of the parenchyma called amyloidoma, and as diffuse cerebral amyloid angiopathy (CAA) and its variant, CAA with angitis of the CNS (CAA/ACNS) (1, 2). There are very few reports (3–8) of CAA and CAA/ACNS presenting as tumefactive mass lesions mimicking neoplasms, and none describes the MR spectroscopic pattern of these lesions or its appear-ance at diffusion-weighted (DW) imaging. In this re-port, we present the imaging findings including those of MR spectroscopy and DW imaging of two cases of diffuse cerebral amyloid angiopathy with tumor-like masses that caused diagnostic dilemmas.