Asymptomatic thoracic Pantopaque cyst mimicking an intradural extramedullary lipoma on MR images

Abstract

Oil-based contrast media such as Pantopaque have not used for imaging for several decades, but because these contrast media have an extremely low clearance rate, the remnant contrast media or residual sequelae of these materials may be encountered in the clinical field. A 63-year-old woman presented to our hospital complaining of increasing lower back pain and lower extremity paresthesia with incontinence for 2 years. A plain X-ray film revealed single droplet-like mass at the lower thoracic T9-T10. A magnetic resonance image (MRI) study revealed a dorsally placed extramedullary intradural lesion, compressing the thoracic cord and minimally displacing it anteriorly. Spinal stenosis was also noted at the L4-5 level. The patient was performed for two consecutive surgeries. Total laminectomy was performed at T9-T10 to remove mass. A 0.5 × 0.5 × 4 cm yellowish intradural extramedullary cystic mass was removed without any leakage of cystic contents. Partial hemi-laminectomy and foraminotomy was then done at L4-5 levels for radiculopathy symptom relief. The fluid from the cyst was composed mainly of iodide. Intraspinal masses showing metal-like density in X-ray or computed tomography but in MRI showing only lipoma or cystic lesions, not metallic characteristics, the differential diagnosis should include iophendylate (Pantopaque) cyst. Oil-based contrast medium is believed to have the potential to make a syrinx formation via arachnoiditis, which can lead to severe neurologic deteriorations, so even if the patients do not represent with an acute neurologic deficit, surgical total removal of remnant material without leaking should be considered.