SINGULAR INCIDENCE OF EXTRANODAL ROSAI–DORFMAN DISEASE (RDD) MIMICKING A CERVICAL INTRAMEDULLARY SPINAL CORD TUMOUR

Rosai–Dorfman disease (RDD) or massive sinus histiocytosis with lymphadenopathy is a rare, benign, lymphoproliferative disorder. CNS involvement is extremely rare and cervical spinal cord manifestation has not been reported. We present a 76-year-old male with a 10 week history of right hemi-paresis. MRI identified enhancing cervical intramedullary lesion consistent with a primary spinal cord tumour variously diagnosed initially as meningioma and Langerhans cell histiocytosis (LCH). Histopathology revealed atypical cells staining for S100 and showing the characteristic emperipolesis, where small lymphocytes or plasma cells were engulfed in histiocyte cytoplasm, indicative of intramedullary RDD. This cervical presentation of RDD-CNS suggests variation in the expected manifestations of the disease necessitating greater clinicopathological awareness.