Unusual, metastatic, or neuroendocrine tumor of the pancreas: a diagnosis with endoscopic ultrasound-guided fine-needle aspiration and immunohistochemistry

Abstract

Background/aim: To determine the yield of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in combination with immunostains in diagnosing unusual solid pancreatic masses (USPM) in comparison with pancreatic adenocarcinoma (ACP).

Patients and methods: All EUS-FNA of solid pancreatic masses performed with a 22-gauge needle were included. Data on clinical presentations, mass characteristics, presence of pancreatitis, yield of tissue, and final diagnosis were compared between the two groups. On site cytopathology was provided and additional passes were requested to perform immunostains.

Results: Two hundred and twenty-nine cases with either adenocarcinoma or USPM were included. The median age of the cohort was 65 years. ACP (210/229, 92%) accounted for the majority of the cases. The USPM included neuroendocrine (NET) masses (n=13), metastatic renal carcinoma (n=3), metastatic melanoma (n=1), lymphoma (n=1), and malignant fibrous histiocytoma (n=1). Subjects with ACP were significantly more likely to present with loss of weight (P=0.02) or obstructive jaundice (P<0.001). Subjects with ACP were more likely to have suspicious/atypical FNA biopsy results as compared with USPM (10% vs 0%). The sensitivity of EUS-FNA with immunostains was 93% in ACP as compared with 100% in USPM. Diagnostic accuracy was higher in USPM as compared with ACP (100% vs 93%).

Conclusions: EUS-FNA using a 22-gauge needle with immunostains has excellent diagnostic yield in patients with USPMs, which is comparable if not superior to the yield in pancreatic adenocarcinoma.

Figure 1

(a) EUS shows a well-circumscribed 1.9 cm pancreatic mass with a small cystic space consistent with a neuroendocrine tumor (Olympus UC 30 P imaging at 7.5 MHz); (b) EUS–FNA cytology shows discohesive to loosely cohesive plasmacytoid cells with abundant cytoplasm and eccentrically placed nuclei. The nuclei are round and have smooth nuclear membranes. Occasional cells show binucleation consistent with a neuroendocrine tumor that is confirmed by immunostains. (Diff quick stain ×40); (c and d) immunostains with chromogranin and synaptophysin confirms the neuroendocrine nature of the tumor in (a)

Figure 2

(a) Endoscopic ultrasound shows a well circumscribed mass in the neck of the pancreas with increased vascularity consistent with renal cell carcinoma. Endoscopic ultrasound-guided fine-needle aspiration (EUS–FNA confirmed the presence of renal cell carcinoma. (Olympus UC 30 P imaging at 7.5 MHz); (b) EUS–FNA shows a group of atypical cells with abundant, finely vesicular cytoplasm and relatively uniform but hyperchromatic nuclei consistent with renal cell carcinoma. (Diff Quick ×400); (c) atypical cells are immunoreactive for CD10, vimentin, and broad spectrum cytokeratin, supporting the diagnosis of metastatic renal cell carcinoma (Pancreas, cell block, ×200, immunohistochemical stain for Renal cell carcinoma)