Endoscopy 2011; 43 - A5
DOI: 10.1055/s-0031-1292076

Evaluation of risk factors for PNET and GIST based on EUS-FNA specimens

Katanuma Akio 1
  • 1Center for Gastroenterology, Teine-Keijinkai Hospital, Japan

Objective:

To examine whether the risk factors of pancreatic neuroendocrine tumor (PNET) and gastrointestinal stromal tumor (GIST) could be accurately evaluated using endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) specimens

Methods:

Three patients with PNET and 17 with GIST who received preoperative EUS-FNA and surgical resection between April 2005 and May 2010 were included. PNET developed in the pancreatic head in 1 patient and in the pancreatic body in 2. All 3 patients with PNET had a final diagnosis of well-differentiated neuroendocrine carcinoma (WDNEC) as evaluated by the WHO Classification. GIST developed in the stomach in 14 patients, duodenum in 2, and rectum in 1. The diameter of GIST was 5cm or larger in 4 patients and less than 5cm in 13. The final risk classification according to the GIST Guidelines of Japanese Society of clinical oncology was low risk in 11 patients, medium in 2, and high in 4. The following points were examined: (1) comparison of the MIB-1 index between the FNA and surgical specimens from the 3 patients with PNET, (2) comparison of the WHO classification before and after operation in the patients with PNET, and (3) comparison of mitosis between the FNA and surgical specimens in the patients with GIST.

Results:

  • The MIB-1 index in the 3 patients with PNET was 4.9%, 2.1%, and 1% for the FNA specimens, and 17.9%, 1.5%, and 4% for the surgical specimens.

  • The preoperative diagnosis based on FNA was well-differentiated neuroendocrine tumor (WDNET) in 1 patient and WDNEC in 2, indicating a concordance rate of 67%. One of the patients had an MIB-1 index of 1.5% based on the surgical specimen, but was diagnosed as WDNEC based to histological findings, including a tendency of vascular invasion.

  • All the patients with GIST had a mitosis level of <5/50 (low to very low risk) based on the FNA specimens, whereas one of them had a mitosis level of 13/50 (high risk) based on the surgical specimen, indicating a concordance rate of 94%.

Conclusions:

The MIB-1 index in PNET was close between the FNA and surgical specimens in some patients, but not in others, suggesting that MIB-1 results based on FNA specimens should be interpreted carefully. The mitosis level in GIST showed a relatively high concordance rate.