Isolated intracranial Rosai-Dorfman disease without dural attachment--case report.

A 33-year-old female presented with an isolated well-enhanced intracerebral lesion with peritumoral edema in the frontal lobe, which was tentatively diagnosed preoperatively as either a primary intraparenchymal neoplasm or metastatic brain tumor. However, histological examinations yielded a diagnosis of Rosai-Dorfman disease. Isolated intracranial Rosai-Dorfman disease is very rare, and without dural attachment, as in our case, is exceptional. The present case mimicked intraparenchymal neoplasm. Rosai-Dorfman disease should be considered in the differential diagnosis of isolated intraparenchymal tumors. Magnetic resonance imaging including diffusion-weighted imaging may be helpful in the diagnosis of isolated intracranial Rosai-Dorfman disease.