Predictors of Malignancies in Patients with Inconclusive or Negative Results of Endoscopic Ultrasound-guided Fine-needle Aspiration for Solid Pancreatic Masses

Abstract

Background/aims: This study analyzed the diagnostic accuracy of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) for pancreatic solid masses in patients with or without chronic pancreatitis as well as the clinical parameters relevant to a malignancy when EUS-FNA was negative or inconclusive.

Methods: A total of 97 patients, who underwent EUS-FNA for solid pancreatic masses over 2 years at a single institution, were evaluated. All patients underwent EUS-FNA for 3-5 passes with 22 or 25 G needles without an on-site cytopathologist. The final diagnosis was obtained by surgery or compatible clinical outcomes for a more than 12 month follow-up. The diagnostic yields in the patients with or without chronic pancreatitis were compared and the histories and laboratory data relevant to pancreatic ductal adenocarcinoma (PDAC) or pseudo-tumor were analyzed.

Results: The final diagnoses were adenocarcinoma in 88 patients (90.7%) and inflammatory pseudo-tumor in 9 (9.3%). The results of EUS-FNA were adenocarcinoma (74), suspicious (7), atypical (5), negative (10), and inadequate specimen (1). The diagnostic accuracies were 76.9% and 91.6% in patients with or without chronic pancreatitis, respectively. Among the 23 cases with non-diagnostic results of EUS-FNA, PDAC was finally diagnosed in 5 out of 7 suspicious, 3 out of 5 atypical, and 5 out of 10 negative cytology cases. The clinical parameters related to a pseudo-tumor were a history of alcohol consumption and pancreatitis, and normal alkaline phosphatase levels.

Conclusions: The diagnostic accuracy of pancreatic masses in the background of chronic pancreatitis was low. When EUS-FNA produced inconclusive results, the histories of alcohol consumption, pancreatitis, and serum levels of alkaline phosphatase are useful for making a final diagnosis.

Keywords: Chronic pancreatitis; Endosonography; Fine needle aspiration; Pancreatic cancer.

Fig. 1

Representative images of the pancreatic cytology (papanicolaou staining, magnification ×400). (A) Positive for a malignancy. (B) Suspicious for a malignancy. (C) Atypical cells. (D) Negative for a malignancy.

Fig. 2

Flow chart of the diagnostic process. Of the 99 patients who underwent EUS-FNA, each patient with a neuroendocrine tumor and metastasis on the pancreas was excluded. Twenty-three patients with negative or non-diagnostic EUS-FNA were included in the analysis of the clinical parameters relevant to pancreatic cancers or pseudo-tumors. EUS-FNA, endoscopic ultrasonography guided fine needle aspiration; PDAC, percentages of pancreatic ductal adenocarcinoma.

Fig. 3

Representative images of a pseudo-tumor (A-C) and pancreatic adenocarcinoma (D-F) in the setting of chronic pancreatitis. (A, D) Abdominal computed tomography scan. (B, E) Positron emission tomography-computed tomography scan. (C, F) Endoscopic ultrasound guided fine needle aspiration.

Fig. 4

Percentages of PDAC or pseudo-tumors according to the number of clinical parameters relevant to pseudo-tumors (alcohol drinking, history of pancreatitis, normal alkaline phosphatase level). The percentages of PDAC were 71.4%, 80%, 20%, and 0% according to the number of clinical parameters of 0, 1, 2, and 3, respectively. PDAC, pancreatic ductal adenocarcinoma.