Rosai-Dorfman disease presenting multiple intracranial lesions with unique findings on magnetic resonance imaging. Case report.

✓ Rosai—Dorfman disease (RDD) is a rare idiopathic histoproliferative disease affecting the systemic lymph nodes. Although an extranodal lesion has also been recognized, central nervous system involvement is extremely rare. To the authors' knowledge, only 20 cases of intracranial lesions have been reported previously. Intracranial RDD is clinically and radiologically difficult to distinguish from meningioma, and histological examination is essential for a definitive diagnosis. The authors treated a large frontal lobe tumor associated with multiple meningeal nodules in a 67-year-old patient presenting with diplopia and headache. Radiological examination indicated that the mass was an inflammatory lesion rather than a meningioma. Microscopically the lesion consisted of mixed inflammatory infiltrate with marked emperipolesis, which is characteristic of RDD. A review of the literature and a discussion of the differential diagnosis of this rare lesion are also presented.