Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
January 2017
Next Case of the Month coming February 7 …
Retained Intrathecal Pantopaque
- Background:
- Iophendylate (Pantopaque or Myodil), introduced in 1941, is an oil-based positive contrast medium used in myelography.
- Reports of Pantopaque retained in either subarachnoid or subdural space began to surface in the late 1980s.
- Clinical use of Pantopaque began to decline due to the introduction of safer, water-soluble contrast media and was officially discontinued in 1988.
- Due to the extremely slow clearance rate (0.5-3cc per year) of Pantopaque, the sequelae of this once widely used contrast material can present decades later.
- Clinical Presentation:
- Pantopaque cysts are usually incidental findings, as they do not typically cause significant symptoms or neurologic deficits.
- Rarely, myelography using Pantopaque has been associated with arachnoid adhesions and cysts causing syringomyelia, compression, or nerve root irritation.
- Key Diagnostic Features:
- Pantopaque demonstrates high signal intensity on T1-weighted MRI and low signal intensity on T2-weighted MRI; thus it may mimic fat or blood.
- Suppression of intrinsic T1 shortening on fat-suppressed images and chemical shift artifacts is presumably due to the high fat content of the contrast.
- Pantopaque has high attenuation (1000-3000 HU) on CT due to its iodine moiety.
- Similarly, Pantopaque appears as a radiopaque droplet-like mass on plain radiograph.
- Pantopaque demonstrates high signal intensity on T1-weighted MRI and low signal intensity on T2-weighted MRI; thus it may mimic fat or blood.
- Differential Diagnosis:
- Lipoma
- Hemangioma
- Hemorrhage
- Melanoma
- Conclusion:
- Pantopaque is an oil-based material that can remain in the subarachnoid space decades after myelography.
- Awareness of this infrequently encountered sequela is important, as it may mimic other intraspinal pathology and, when diagnosed, can obviate surgical intervention.