Spine-limited Rosai–Dorfman disease in a patient with ankylosing spondylitis – A rare mimicker of spinal tumors

Background: Rosai-Dorfman disease (RDD) is an uncommon histiocytic proliferative disorder that typically involves the lymph nodes but can also present with extranodal involvement. Central nervous system involvement is rare, and the spine-restricted RDD is an extremely rare variant that poses significant diagnostic challenges, often resulting in delays in diagnosis and management. Case Description: We report a case of a 32-year-old gentleman with a history of back pain for 1-year, initially being managed as ankylosing spondylitis, which subsequently developed spastic paraparesis and was ultimately diagnosed with spine-restricted RDD. Conclusion: Recognizing this rare entity and its potential associations with immune-mediated conditions, such as human leukocyte antigen B27-related spondyloarthropathies and possibly inflammatory bowel disease, is essential to avoid misdiagnosis and guide individualized, multidisciplinary treatment strategies.