Multilevel thoracic ossification of the yellow ligament in a Cowden syndrome patient.

We present an exceptionally rare case of a late 30 s female with a known history of Cowden syndrome who developed extensive thoracic ossification of the yellow ligament (OYL) causing severe spinal cord compression. OYL is the abnormal ossification of the ligamentum flavum that can compress the spinal cord. The patient underwent a T10-11 posterior decompressive laminectomy and fusion that resulted in recovery of ambulatory function and improvement of motor strength. This case raises awareness of OYL as a potential, though unconfirmed, complication in patients with PTEN-related disorders, highlighting the possible value of spinal surveillance in this population.