Unusual presentation of an extrahepatic migration of a fiducial implanted for stereotactic body radiotherapy
Meenu Jose, George Shibu Pottikyal, Ajay Sasidharan, Sruthi K Reddy, Annex Edappattu Haridas and Debnarayan Dutta
We report an unusual case of extrahepatic migration of fiducial in a patient diagnosed with hepatocellular carcinoma with portal vein thrombosis planned for stereotactic body radiotherapy (SBRT) using Cyberknife (CK). The fiducial migrated from liver to abdomen within one hour after placement and kept migrating for 24 h until it got lodged into the right gluteus maximus muscle. There was no complication reported. Patient was on follow up with regular observation. We are describing the potential migration pathway of fiducials after placement in liver, possible intervention procedures and the potential complications.
Fiducials or internal markers are an integral part of ‘real time’ tumour tracking. ‘Real time’ tumour tracking potentially reduces internal target volume (ITV) margin and hence reduces the high dose volume. Internal fiducials are useful for tumour tracking in image guided radiation therapy for mostly liver, lung and prostate cancer. Fiducial implantation is used for SBRT as surrogate for tumour motion in both linear accelerator based or CK radiosurgery platform (1-2). Implantation of fiducial markers is usually safe with very rare complications in less than 3% cases (3-6). Migration outside the implanted organ has been documented in less than 5% of cases (4, 7). However, fiducials have the potential to migrate in critical organs and have a potential to cause serious consequences (8-10). There is a need to track the potential path of migration and evaluate any need for intervention in situations where there is a potential for severe complication. In the present case scenario, the fiducial was displaced from the liver and the path of migration was documented with time interval images.
Keywords: CyberKnife, extrahepatic migration, fiducial implant, hepatocellular carcinoma, portal vein thrombosis