Pancreatic neuroendocrine tumor with stenosis of the main pancreatic duct leading to pancreatic pleural effusion: a case report

Abstract

Background: Pancreatic pleural effusion and ascites are defined as fluid accumulation in the thoracic and abdominal cavity, respectively, due to direct leakage of the pancreatic juice. They usually occur in patients with acute or chronic pancreatitis but are rarely associated with pancreatic neoplasm. We present here an extremely rare case of pancreatic neuroendocrine tumor with stenosis of the main pancreatic duct, leading to pancreatic pleural effusion.

Case presentation: A 51-year-old man complained of dyspnea. Left-sided pleural effusion was detected on the chest X-ray. Pleural puncture was performed, and the pleural fluid indicated a high amylase content (36,854 IU/L). Hence, the patient was diagnosed with pancreatic pleural effusion. Although no tumor was detected, the computed tomography (CT) scan showed a pseudocyst and dilation of the main pancreatic duct in the pancreatic tail. Magnetic resonance cholangiopancreatography showed a fistula from the pseudocyst into the left thoracic cavity. Endoscopic retrograde pancreatic drainage was attempted; however, it failed due to stenosis in the main pancreatic duct in the pancreatic body. Endoscopic ultrasound revealed a hypoechoic mass measuring 15 × 15 mm in the pancreatic body that was not enhanced in the late phase of contrast perfusion and was thus suspected to be an invasive ductal carcinoma. The patient underwent distal pancreatectomy with splenectomy and the postoperative course was uneventful. Histopathological examination confirmed a neuroendocrine tumor of the pancreas (NET G2). The main pancreatic duct was compressed by the tumor. Increased pressure on the distal pancreatic duct by the tumor might have caused formation of the pseudocyst and pleural effusion. To the best of our knowledge, this is the first case report of pancreatic pleural effusion associated with a neuroendocrine tumor.

Conclusions: Differential diagnosis of a pancreatic neoplasm should be considered, especially when a patient without a history of pancreatitis presents with pleural effusion.

Keywords: Internal pancreatic fistula; Pancreatic ascites; Pancreatic neuroendocrine tumor; Pancreatic pleural effusion; Pseudocyst in the pancreatic tail; Stenosis of the main pancreatic duct.

Fig. 1

Findings of computed tomography (CT). CT reveals left-sided pleural effusion (a). Pancreatic pleural effusion was diagnosed on pleural puncture, based on the high amylase content (36,854 IU/L) in the pleural fluid. b CT shows a pseudocyst (arrow). c Dilation of the main pancreatic duct (arrow) in the pancreatic tail. No tumor can be observed in the pancreas

Fig. 2

Findings of magnetic resonance cholangiopancreatography (MRCP). MRCP shows a fistula (arrow) from the pseudocyst (arrowhead) into the thoracic cavity (asterisk)

Fig. 3

Findings of endoscopic ultrasound (EUS). a EUS reveals a hypoechoic mass measuring 15 × 15 mm in the pancreatic body. b The tumor shows hypoenhancement in the late phase of contrast EUS

Fig. 4

Resected specimen. a The resected specimen. Cutting lines of the resected specimen are shown (lines). b Gross description. The tumor cells represented in the circled area. c Solid tumors are seen in the macroscopic specimen

Fig. 5

Findings of histopathological analysis. The tumor appears as a solid neoplastic lesion covered with a fibrotic capsule, and it measures 19 × 17 × 14 mm. Hematoxylin and eosin (HE) staining shows fibrosis. a HE, low-power microscopic view. The main pancreatic duct (square) is compressed by the tumor and narrowed. b HE, high-power microscopic view. In the tumor, eosinophilic cells show a ribbon-like arrangement. c Each cell shows swollen nuclei, anisonucleosis, and atypia. There were 9 mitoses observed in 10 high-power fields

Fig. 6

Findings of immunohistochemistry. Immunostaining shows positivity for chromogranin A and synaptophysin