Progressive Pseudorheumatoid Dysplasia Presenting with Cauda Equina Compression: A Case Report

Background Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive skeletal dysplasia frequently misdiagnosed as juvenile idiopathic arthritis because of overlapping clinical features.  Case presentation We report a 21-year-old man who presented with bilateral leg pain and acute progressive lower-limb weakness associated with gait disturbance. Clinical examination revealed asymmetric motor weakness, absent knee and ankle reflexes, and preserved bowel and bladder function. Radiographs demonstrated generalized platyspondyly, scoliosis, and epiphyseal enlargement of long bones. Magnetic resonance imaging revealed a right paracentral L1-L2 disc extrusion causing severe central canal stenosis with compression and displacement of cauda equina nerve roots. Laboratory investigations were negative for inflammatory markers. Whole-exome sequencing identified a homozygous missense variant c.1010G  A (p.Cys337Tyr) in the CCN6 gene, confirming the diagnosis of PPD. The patient underwent posterior decompressive laminectomy with stabilization, resulting in complete neurological recovery at six weeks. Conclusion This case highlights the rarity of acute cauda equina syndrome in PPD and emphasizes the importance of early recognition and appropriate surgical management.