We report a case of 54 year old patient harboring a solitary painless mass of the calvarium. There was a well-defined biparietal lytic lesion on plain skull radiographics. Computed tomography showed a large hyperdense lesion. This lesion was extraaxial and nearly isointense with gray matter on T1 and T2-weighted MR images, and diffusely enhanced after gadolinium injection. Angiography showed hyperovascularity supplied by middle meningeal and superficial temporal arteries. Imaging study bore some similarities to meningioma. A large extra-axial mass with an important lytic lesion should have led to the diagnosis of plasmocytoma.