Solid pancreatic lesions: etiology, morphology and utility of macroscopic on-site evaluation in predicting good yield of endoscopic ultrasound-guided biopsy

Introduction
Solid pancreatic lesions (SPL)s can be due to various etiologies, and their management depends on the histologic diagnosis.

Aim
The aim of this study was to document the etiology, morphology, and utility of macroscopic on-site evaluation (MOSE) in predicting good yield of endoscopic ultrasound (EUS)-guided biopsy.

Material and methods
All patients with SPLs referred for EUS-guided biopsy were included in the study. Etiology, morphology and results of EUS-guided biopsy were recorded. Rapid on-site evaluation (ROSE) was not available; therefore, MOSE was performed by an endoscopist. Macroscopically, MOSE was considered satisfactory if at least 1 tissue core at least 1 inch long was secured. Histopathologically, a biopsy specimen was considered to have a good yield if it was sufficient to establish a diagnosis. Factors predicting good yield of biopsy (GYB) were identified.

Results
Of the total 176 patients included in the study, 111 (63.1%) were male (mean age 53.8 (±12.6) years; range: 14–80 years). Good yield biopsies (GYB) numbered 144 (81.8%); among them, 97 (67.4%) were neoplastic and 47 (32.6%) non-neoplastic SPLs. The commonest neoplastic SPLs were pancreatic ductal adenocarcinoma (PDA) (76; 78.3%), neuroendocrine tumors (NETs) (13; 13.4%), metastasis (5; 5.1%), and others (3; 3.1%), while the commonest non-neoplastic SPLs were mass-forming chronic pancreatitis (MFCP) (33; 70.2%), autoimmune pancreatitis (AIP) (5; 10.6%), and tuberculosis (2; 4.3%). PDAs were more common in older patients (65/76; 85.5%) and in the head region of the pancreas (47; 61.8%), while NETs were more common in younger patients 7/13 (53.8%) and in the body of the pancreas 5/13 (38.5%). Factors predicting GYB were SPL size > 15 mm (p = 0.045), use of fine needle biopsy (FNB) needles (p = 0.001), ≥ 2 passes (p = 0.001), and satisfactory MOSE (p  0.0001) on univariate analysis; and FNB use (p = 0.049) and satisfactory MOSE (p = 0.001) on multivariate analysis. Our criteria for satisfactory MOSE had high sensitivity (85.4%), positive predictive value (95.35%), and diagnostic accuracy (84.7%).

Conclusions
The commonest neoplastic SPLs are PDA and NET, and the commonest non-neoplastic SPLs are MFCP and AIP. PDAs have a predilection for the head region and older age, while NETs have a predilection for younger patients and the body of the pancreas. A good biopsy yield is likely with use of FNB needles and satisfactory MOSE.