Establishment of a modified percutaneous CT-guided paraspinal intramuscular VX-2 squamous cell carcinoma dual tumor model in rabbits

Background The rabbit VX-2 tumor model is a commonly used transplanted tumor model and is widely used in surgical, radiological, and interventional studies. Most of the known tumor models for each site are single solid tumors. This study aimed to establish an accurate and stable intramuscular dual tumor model guided by computed tomography (CT). Methods In this study, we compared three different inoculation methods to select the most appropriate dual tumor model. Six New Zealand White rabbits were used as tumor-carrying rabbits for tumor harvesting. Thirty rabbits were divided into three groups as experimental rabbits. Group A applied the tumor cell suspension method, in which the suspension was injected into the designated location with a syringe under CT guidance. Groups B and C used tumor tissue strips obtained in vivo or under direct in vitro vision. The tumor tissue strips were implanted into the designated locations using a guide needle under CT guidance. The differences in tumorigenic rate, the size difference between bilateral tumors, and metastasis between the three methods were compared. Results It was found that group A obtained a 100% tumor survival rate, but the size of the tumor was more variable, and needle tract implantation metastasis occurred in 5 cases. In group B, tumor tissue strips were taken in vivo for implantation, in which one case failed to survive. Tumor tissue strips in group C were obtained in vitro under direct vision. The tumor tissue strips obtained in vitro by puncture using a biopsy needle in group C had a 100% tumorigenicity rate and stable tumor size. No significant needle tract implantation metastases were found in either group B or C. The variance of tumor size obtained in group A was significantly higher than in groups B and C. The variance of tumor size in group C was the smallest. Group C had high tumorigenicity and a more stable size and morphology of the formed tumors. Conclusion The results showed that the method of obtaining tumor tissue strips using in vitro direct vision puncture and implanting them into the muscle with CT guidance and guide needles can establish an accurate and stable dual tumor model. This dual tumor model can provide substantial support for relevant preclinical studies.

Needle Tract Implantation Following Fine-Needle Aspiration of Thyroid Cancer

Background Needle tract implantation (NTI) can occur after thyroid fine-needle aspiration cytology (FNAC). To date, no studies enrolling a large number of patients and studying the cumulative incidence (CI) of NTI have been published. This study analyzed the clinicopathological features of NTI and calculated the CI. Methods A total of 11,745 patients who underwent first FNAC, resection for thyroid carcinomas and related lymph node metastases, and postoperative ultrasonography in Kuma Hospital between 2006 and 2017 were evaluated. NTI was defined as macroscopically visible and/or sonographically detected recurrent tumors at the sites of the previous aspiration. Lymphovascular invasion and/or nodal metastasis were excluded. Results We found 22 NTI-THY (originated from aspiration of thyroid tumors) and 8 NTI-LN (originating from lymph nodes) cases with CI of 0.15% and 0.37%, and 0.37% and 0.58% at 5 and 10 years after FNAC, respectively. A large percentage (53%) of cases are presented as more aggressive histologic subtypes than their original tumors. Of these NTI patients, 4 (12.1%) died of disease and 10 (33.3%) developed distant metastases but remained alive with stable disease, three (9.1%) developed local recurrences, and the remaining 15 (10%) were free of recurrence. Conclusions We demonstrated for the first time the CI and detailed clinicopathological features of thyroid NTI associated with possible histological transformation. Despite the low CI, the risk of death and distant metastases increase manifold in NTI patients than that in patients without recurrence. Therefore, NTI could be an important prognostic variable and impact patient survival.