Female, 51 years old, with mild erosion of the calvarium. An extra-axial mass with a broad base of dural attachment is seen along the left paramedian vertex measuring up to 21 mm in AP length and up to 13 mm in thickness. The lesion is mildly enhancing. The lesion barely contacts the underlying brain parenchyma causing no significant parenchymal edema. It does, however, appear to infiltrate the overlying calvarial bone, permeating through the inner table and thinning but not definitely eroding through the outer table.No additional enhancing lesions are seen intra or extracranially. Scattered nonspecific foci of T2 hyperintensity are seen within the cerebral hemispheres without significant mass effect. No restricted diffusion is seen. No intracranial hemorrhage or abnormal extra-axial fluid collections are detected. The ventricular system is normal in size and morphology.
A small extra-axial mass is seen along the left vertex with invasion into the overlying skull. The differential diagnosis would include meningioma, perhaps an atypical variant given the osseous erosion. Other mesenchymal tumors including hemangiopericytoma and hemangioendothelioma can be considered. Although metastasis would be unusual without a known primary, this would technically be in the differential as well.