A 45-year-old woman presented with an isolated, contrast-enhancing brain lesion in white matter of the right frontal lobe, preoperatively thought to be either a primary brain neoplasm or metastasis. The lesion was demonstrated by histology and immunohistochemistry to be Rosai-Dorfman disease. Central nervous system (CNS) manifestations of this disease are rare. There have been 27 cases of intracranial involvement reported previously. All of them have been dural-based, where the disease clinically and radiologically resembles meningioma. To our knowledge, this is the first case of an isolated intraparenchymal CNS lesion without dural attachment, where the clinical and radiological features resembled an intraparenchymal glial neoplasm, lymphoma or metastatic tumor.