Osteoma arising from the lumbar articular process.

A 57-year-old man presented with an extremely rare osteoma originating from the left L-5 inferior articular process and causing lumbo-crural sciatica. Postmyelography computed tomography and magnetic resonance imaging showed an osteoma compressing the spinal nerve root at the lateral recess. Decompression facetectomy and excision of the lesion followed by transforaminal lumbar interbody fusion between L-5 and S-1 provided complete relief from the symptoms. Histological examination confirmed the diagnosis of benign osteoma. The previous seven cases of spinal osteoma involved the vertebral body, pedicle and posterior elements. Spinal osteomas should be considered in the differential diagnosis of benign lesion originating from the articular process.