Evaluating the safety and diagnostic accuracy of endoscopic fine-needle aspiration for detection of extravascular migratory metastases in the pancreas

Oct. 22, 2019

Malignant vascular invasion impacts cancer staging, therapy and survival. Often identified during surgery or autopsies, tumor cells can migrate to distant sites along the surface of blood vessels and form extravascular migratory metastases (EVMM).

A team of Mayo Clinic researchers sought to evaluate the feasibility and safety of using endoscopic ultrasound fine-needle aspiration (EUS-FNA) of perivascular soft tissue cuffs to detect EVMM in the pancreas. The results of this study were published in Clinical Gastroenterology and Hepatology (CGH) in 2019.

Study methods

The researchers performed a retrospective analysis of 253 patients (mean age, 62 ± 12 years) who underwent EVMM of 267 vessels for evaluation of suspected EVMM, from April 2001 through May 2018. Researchers documented patient demographics, imaging technique, pathology, clinical management and outcome data. They included noninvasive cross-sectional imaging to detect EVMM using computerized tomography (CT) and magnetic resonance imaging (MRI) as the reference standard. And they identified malignancy using cytology analysis of FNA samples, histology analyses of surgical or biopsy specimens, or vascular abnormalities detected by CT or MRI that clearly indicate EVMM.

The researchers compared findings obtained using EUS-FNA analysis with those obtained via noninvasive cross-sectional imaging, and they studied how these findings influenced staging and determination of resectability in pancreatic tumors.

Key findings

  • Thirty patients were found to have benign lesions. The remaining 223 patients with malignancies, 166 with pancreatic ductal adenocarcinomas (PDACs), underwent further analyses. A median of four FNAs (range, 1 to 20) were obtained from 4-mm perivascular soft tissue cuffs (range, 2 to 20 mm).
  • FNA and cytology analysis showed malignant cells in 163 vessels (69.4%) from 157 patients (70.4%).
  • CT or MRI did not detect EVMM in 44 patients (28%) with malignancies, including 24 patients (24%) with newly diagnosed PDAC.
  • After detection of EVMM by EUS-FNA, 15 patients were upstaged and 14 patients with PDAC were re-categorized from resectable (based on CT or MRI) to unresectable.
  • No adverse events were reported during a follow-up period of 3.9 months (range, 0 to 117 months).


Overall, the researchers conclude that cytology analysis of pancreatic samples collected by EUS-FNA can provide a safe and accurate means to detect EVMM often missed by cross-sectional imaging.

"Endoscopic ultrasound fine-needle aspiration is emerging as an effective tool for vascular diagnosis and therapy," explains Michael J. Levy, M.D., a gastroenterologist at Mayo Clinic's campus in Rochester, Minnesota, and a lead author on the study published in CGH. "EVMM can be difficult to detect and diagnose using CT and MRI because inflammation and therapy-induced changes can affect imaging features," says Dr. Levy.

"In patients with known pancreatic lesions, this tool also demonstrated the capacity to help accurately stage tumors and determine resectability," adds Dr. Levy. "Performing cytology analysis of pancreatic samples collected by EUS-FNA could increase the accuracy of tumor staging and determination of tumor resectability."

For more information

Rustagi T, et al. Safety, diagnostic accuracy, and effects of endoscopic ultrasound fine-needle aspiration on detection of Q1 extravascular migratory metastases. Clinical Gastroenterology and Hepatology. In press.