INVESTIGATIONS AND DIAGNOSIS
Upon experiencing dizziness and palpitations following admission, intravenous blood glucose measured 32.58 mg/dL, insulin level was 108.7 mIU/L, and the insulin release index (IRI/G) was calculated as 3.32. The results of the glucose tolerance test, C-peptide measurement, and insulin release test are presented in Table 1. Abnormal findings included blood tests, liver and kidney function, glycosylated hemoglobin levels, tumor markers, adrenocorticotropic hormone, cortisol, thyroid function, parathyroid hormone, growth hormone, and sex hormones. Thyroid function, parathyroid hormone, growth hormone, and sex hormone levels were within normal limits. Abdominal imaging revealed no abnormalities. Ultrasound endoscopy revealed a hypoechoic nodule in the pancreatic neck, measuring approximately 11.2 × 12.7 mm (Figure 1). Ultrasound endoscopy-guided puncture of the pancreatic nodule revealed pancreatic tissue strip lesions, characterized by epithelioid cells arranged in a nest-like pattern. Uniform cell size and cytoplasmic richness were noted. A neuroendocrine tumor was suspected (Figure 2 and Figure 3). Following transfer to general surgery department, post-abdominal exploration revealed an approximately 1 cm diameter nodule in the pancreatic neck (Figure 4). Intraoperative ultrasound confirmed a hyperechoic nodule in the same location. Pancreaticoduodenectomy was subsequently performed. The postoperative autopsy specimen revealed a well-defined mass, measuring 1.2 × 1.4 cm, located in the pancreatic neck (see Figure 5). The intraoperative rapid pathology report confirmed the presence of a neuroendocrine tumor. Postoperative histopathology demonstrated anisotropic cell proliferation within the pancreatic tissue, characterized by glandular duct-like and small nest-like structures(see Figure 6). The tumor cells exhibited uniformity and minimal heterogeneity, consistent with a neuroendocrine tumor.