Castleman Disease masquerading as the lumbosacral neurofibroma with excellent response to rituximab

Castleman's disease is an uncommon, lymphoproliferative disease. Its etiology is unknown. Spine involvement is very scant in Castleman's disease. The authors report on the case of a 50 year-old man who referred with saddle anesthesia and low back pain from 2.5 years ago. A CT scan showed an extra medullary mass at S1-S2 level of the spinal canal without bone involvement. The signal specs on MRI were resembling to signal of neurofibroma .The patient underwent needle biopsy. Histological examination confirmed the diagnosis of Castleman disease, hyaline-vascular type. He received rituximab and pain was dramatically relieved. Although rare, Castleman disease should be considered in the differential diagnosis of an extramedullary mass.