Aggressive adenoid cystic carcinoma with asymptomatic spinal cord compression revealed by a "curtain sign".

The authors present a case of unusually aggressive adenoid cystic carcinoma of the head and neck. The patient presented with sciatica one year after initial diagnosis. She was otherwise asymptomatic. Complete work-up for bone involvement, included bone scan and MRI. The patient had painful osteolytic sacral metastasis and asymptomatic thoracic (T5) vertebral metastasis revealed by a typical curtain sign on MRI. The curtain sign, originally described by Trolard, is due to the displacement of the Trolard's membrane with the median ligament attaching the dura to the bone while there is a dorsal displacement and loosening of the posterior longitudinal ligament. The patient benefited from radiotherapy and did not develop respiratory distress, paraplegia or pain but died of liver metastases.