Macroscopic qualitative evaluation of solid pancreatic lesion specimens from endoscopic ultrasound-guided fine needle aspiration/biopsies

Abstract

Objectives: To pathologically clarify the macroscopic features of endoscopic ultrasound-guided fine needle aspiration/biopsy (EUS-FNA/B) specimens in representative pancreatic diseases and establish tissue-handling standards based on the macroscopic findings.

Methods: We gathered EUS-FNA/B specimens of cases at our institution with the final diagnoses of pancreatic ductal adenocarcinoma (PDAC, n = 172), neuroendocrine tumor (NET, n = 19), and chronic inflammatory lesion (CIL, n = 24) including autoimmune pancreatitis. We classified the specimens' macroscopic features in five categories (red strings, mixed-red-and-white strings, white cores, gray tissues, gelatinous tissues) and compared the specimens' features on cytological and histological slides.

Results: All five macroscopic categories were observed in variable combinations in the PDACs; red strings and white cores predominated in the NETs and CILs. White cores represented neoplastic (PDAC, NET) or lesion (CIL) tissues. Mixed-red-and-white strings were unique to PDACs and contained cancerous cells. Neoplastic cells were numerous in red strings in NETs but not the other groups. Gray and gelatinous tissues represented necrosis and mucin, respectively, and the former were almost exclusively observed in PDACs. Red strings, mixed-red-and-white strings, and white cores were suitable for histological examination, whereas gray and gelatinous tissues were suitable for cytological examination. The white cores, mixed-red-and-white strings, and gelatinous tissues may be composed of non-neoplastic tissues such as contaminated gastrointestinal epithelium. In seven PDACs, although white cores were obtained, a histological diagnosis was not established.

Conclusions: Macroscopic evaluations of EUS-FNA/B can enable the identification of specimen components and a possible diagnosis. They also contribute to the selection of the optimal tissue-handling methods.

Keywords: Autoimmune pancreatitis; Endoscopic ultrasound-guided fine needle aspiration; Neuroendocrine tumor; Pancreatic ductal carcinoma; Rapid on-site evaluation.