Tumefactive dilated perivascular space with spontaneous regression.

Tumefactive (giant) perivascular spaces of the brain are a rare benign lesion that may occasionally result in localized neurological symptoms and typically do not change in appearance on subsequent imaging studies. Here we report a case of a 65-year-old woman with newly diagnosed lung cancer that underwent routine staging MRI of the brain. She was found to have a cystic temporal lobe lesion with imaging features consistent with a tumefactive perivascular space. Accurate diagnosis of this lesion was imperative in this case to avoid incorrect staging. On subsequent MRI, the lesion had markedly regressed without interval intervention further confirming the diagnosis. This case report presents the unique imaging features and presentation of this lesion to avoid unnecessary biopsy or resection.