Needle-tract seeding after percutaneous cryoablation for lung metastasis of colorectal cancer.

We report two cases of needle-tract seeding after percutaneous cryoablation for lung metastases of colorectal cancer. The targeted lung tumor was solitary in both cases. In patient 1, cryoablation was performed with a single cryoprobe, which was removed without freezing the cryoprobe tract. In patient 2, cryoablation was performed with two cryoprobes, both of which were removed after freezing of the cryoprobe tract. The seeding nodule appeared 5 and 7 months after cryoablation on the follow-up computed tomographic scan, respectively. In both cases, the seeding nodules were solitary and existed primarily in the subcutaneous to chest muscle layer, and could be completely resected under local anesthesia. Both lesions were pathologically confirmed as metastases from colorectal cancer. Local control was maintained in patient 1 for 4 years, until death due to progressive lung metastases. Patient 2 is alive without recurrences 8 months after resection.