Pancreatic Neuroendocrine Tumor Leading to a Diagnosis of Multiple Endocrine Neoplasia Type 1

Abstract

Pancreatic neuroendocrine neoplasms are rare but occasionally encountered. They are generally highly vascularized solid tumors, often round in shape with clear boundaries, defined contours, and a homogeneous internal structure. However, they can also present with atypical features, such as cystic degeneration, hemorrhage, calcification, and fibrosis, making diagnosis difficult in some cases. They are also known as comorbidities of multiple endocrine neoplasia type 1 (MEN1). This report describes a case in which endoscopic ultrasound (EUS) led to a diagnosis of MEN1. A 50-year-old man was referred to our hospital for examination of a mass in the pancreatic body. An EUS-guided fine-needle biopsy was performed, and a histological diagnosis of neuroendocrine tumor (NET) was made. In addition, the NET was also identified in the duodenum. Serum calcium and parathyroid hormone levels were elevated. Examination of the parathyroid and pituitary glands revealed concurrent hyperparathyroidism and a pituitary adenoma, confirming the diagnosis of MEN1, including a NET in the duodenum.

Keywords: endoscopic ultrasound | hyperparathyroidism | multiple endocrine neoplasia type 1 | pancreatic neuroendocrine tumor | pituitary adenoma.

FIGURE 1

Findings on computed tomography (CT). (A) Plain. (B) Arterial phase. (C) Portal venous phase. (D) Delayed phase. On contrast‐enhanced CT, a slight hypervascular mass was observed in the arterial phase at the location indicated by the arrow.

FIGURE 2

Findings on endoscopic ultrasound. (A) A 20‐mm hypoechoic mass with relatively clear borders was seen in the pancreatic body. (B) Endoscopic ultrasound‐guided fine‐needle biopsy was performed on the mass in the pancreatic body via the stomach. (C) Contrast‐enhanced harmonic endoscopic ultrasound showed a slight enhancement of the mass in the pancreatic body from an early stage.

FIGURE 3

Microscopic observations for the pancreatic tumor. A pancreatic biopsy was performed, and the sample was analyzed by hematoxylin‐eosin staining (A) and immunohistochemical detection using (B) anti‐synaptophysin, (C) anti‐chromogranin A, and (D) anti‐gastrin. The tumor cells had uniform rounded nuclei and pale acidophilic cytoplasm. Scale bar, 50 µm. No mitotic cells were found. The tumor showed synaptophysin and chromogranin positivity, with a Ki‐67 labeling index of less than 1%. The tumor did not express gastrin.