Spina bifida occulta (SBO) is the mildest form of closed spinal dysraphism and is characterized by incomplete fusion of the posterior vertebral elements without involvement of the spinal cord or meninges. It is frequently asymptomatic and often detected incidentally. However, associated structural anomalies may coexist.

We describe the case of a 21-year-old male with known beta-thalassemia who presented with a slowly enlarging swelling over the lower back. MRI of the spine revealed a defect in the posterior vertebral arch at the S2 level along with bifid spinous processes at L3 and L4, consistent with the findings of spina bifida occulta. In addition, a sizable high-flow vascular lesion was noted within the posterior subcutaneous tissues and paraspinal muscles, extending from L1 to S3. The lesion demonstrated numerous serpiginous signal voids on routine sequences and showed heterogeneous enhancement following contrast administration. Subsequent Doppler ultrasound evaluation demonstrated prominent arterial inflow and venous outflow channels, supporting the diagnosis of a paraspinal arteriovenous malformation. There was no evidence of extension into or communication with the thecal sac.