Pancreatic neuroendocrine tumour-insulinoma presenting primarily with altered consciousness and behavioral disturbances: A Case Report

Pancreatic neuroendocrine tumour-insulinoma presenting primarily with altered consciousness and behavioral disturbances: A Case ReportWei Wua, Rixin Zhanga, Xiaowan Lib, Xinhua Wua, Ling Zhua, Zhi ZhengaaDepartment of Hepatopancreatobiliary Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China, Gusao Tree Road No. 16 of Jianghan District, Wuhan 430000, Hubei Province, China.bDepartment of Thyroid and Breast Surgery, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China, Gusao Tree Road No. 16 of Jianghan District, Wuhan 430000, Hubei Province, China.Correspondence: Zhi Zheng (13907164203@163.com)Funding: The author(s) received no financial support for the research, authorship, and/or publication of this articleKeywords: hypoglycemia, pancreatic neuroendocrine tumor, therapy, abnormal behavior, insulinomaAbstractThis case reports a typical example of a rare pancreatic neuroendocrine tumor—insulinoma. The patient was initially diagnosed with behavioral abnormalities. Upon recurrence and subsequent medical evaluation, his blood glucose was measured as low as 1.3 mmol/L, with symptoms resolving after food intake. He was suspected to have a neuroendocrine tumour and diagnosis was established by a series of tests. He underwent surgery andpresently remains asymptomatic. This article aims to tell us that a key clinical principle is that insulinoma must be considered in the differential diagnosis for any patient with recurrent, unexplained episodes of hypoglycemia.1 IntroductionPancreatic neuroendocrine tumors (PNETs), rare pancreatic masses derived from the organ’s well-differentiated endocrine cells, constitute a distinct category of pancreatic tumors [1]. Despite their classification as rare malignancies, PNETs have been observed with increasing frequency across the United States and many other regions in recent years [2]. These tumors can be further classified as either hyperfunctioning or non-hyperfunctioning, based on the presence or absence of clinical syndromes caused by excessive hormone secretion (e.g., insulin, glucagon, gastrin) [3]. Functioning tumors are defined by the presence of a hormonal syndrome. Nonfunctioning tumors, which constitute the majority, do not present with such syndromes. This may be because they secrete no hormones, secrete hormones at biologically inactive levels, or secrete hormones that do not cause a recognized clinical syndrome [4].Functioning insulinoma, a rare neuroendocrine tumor (incidence: 1–4 per million), is being detected more frequently, owing to advances in diagnostic methods [5]. Originating predominantly in the pancreas, these insulinomas induce episodic hypoglycemia. The resulting attacks present with two categories of symptoms: autonomic (tremors, diaphoresis) and neuroglycopenic (confusion, behavioral abnormalities, seizures). Diagnosing insulinomas can be challenging due to the variable nature of symptoms, which may manifest not only during fasting or after exercise but also in the postprandial state [6]. Consequently, the variable presentation of insulinoma frequently leads to diagnostic delays and misdiagnosis, with symptoms often being attributed to more common psychiatric, gastrointestinal, cardiac, or neurological disorders [7].This article reports a case of a pancreatic body mass patient, whose postoperative pathology suggested neuroendocrine tumor ( NET G2 ), with no evidence of lymphovascular or perineural invasion. Laparoscopic pancreatic tumor resection was performed, and the patient recovered well without complication. Through this case, we aim to consolidate the existing knowledge related to PNETs, including its epidemiological characteristics, diagnostic methods, treatment strategies, and other aspects.2 Case Presentation2.1 Present IllnessThis is a 37-year-old male who presented with paroxysmal transient consciousness and behavioral disturbances (The primary manifestation was paroxysmal transient consciousness and behavioral disturbances.) for 1 month, self-measured blood sugar below normal, alleviated after eating, with no dizziness, headache, chest tightness, or chest pain. Since illness onset, appetite was normal, mood and sleep good, with no significant change in body weight.2.2 Past Medical History, Family History, and Physical Examination FindingsPast medical history included hyperlipemia, treated with fenofibrate 200mg qd. The patient denied any family history of similar conditions, including psychiatric disorders, neoplasms, or hereditary diseases. Physical examination: The patient is alert, with a natural expression, and provides coherent responses. No jaundice was observed in the skin or mucous membranes. Visual inspection revealed a flat abdomen with no visible gastrointestinal patterns, peristaltic waves, masses, or dilated abdominal wall veins. Palpation demonstrated a soft abdomen without significant tenderness, rebound tenderness, or muscle guarding. Muscle strength and tone in all four limbs are normal. Physiological reflexes are present, and pathological reflexes are not elicited. Height: 174 cm, Weight: 105 kg, BMI: 34.69.2.3 Imaging StudiesEnhanced CT revealed a well-defined, round, solid hypervascular nodule in the body of the pancreas, measuring approximately 1.6×2.0 cm. On contrast-enhanced scans, it showed uniform and marked enhancement, most pronounced in the portal venous phase, suggesting a high likelihood of a neuroendocrine tumor (likely insulinoma) (Figure 1).3 Differential Diagnosis, Investigations, and Treatment3.1 Differential Diagnosis3.1.1 Pancreatic CancerIn its initial phases, pancreatic carcinoma is frequently characterized by a lack of noticeable symptoms. In advanced stages, symptoms such as jaundice, back pain, and weight loss may emerge. Elevated serum levels of CA19-9 are frequently observed. On plain CT imaging, the tumor demonstrates variable attenuation, ranging from isodense to mixed isodense and hypodense when compared to the adjacent normal pancreatic parenchyma. On contrast-enhanced CT, it demonstrates poor early-phase enhancement (often minimal, slow, and heterogeneous) due to its hypovascular nature. This patient has hypoglycemic symptoms and the enhanced CT showed a hypervascular nodule. The diagnosis is highly suspected but requires surgical pathology for confirmation.3.1.2 Intraductal Papillary Mucinous Neoplasm (IPMN)Based on the contrast-enhanced CT and biopsy findings, this specific diagnosis is not currently favored. However, it requires exclusion via postoperative pathology. The entity is characterized typically by mucin-related cystic duct dilation, or less often, papillary proliferation-induced dilation. It shows a slight male predominance and an average age of onset of 65 years. Patients most commonly present with pancreatitis symptoms, but incidental detection is also possible.3.1.3 Pancreatic pseudocystPancreatic pseudocysts are complications secondary to acute or chronic pancreatitis or pancreatic injury. Most pancreatic pseudocysts may be asymptomatic, while symptomatic pseudocysts are often related to the location of the cyst and the nature of its fluid. Enhanced CT can clearly visualize the cyst’s location, size, number, wall thickness, and its relationship with surrounding organs and blood vessels.3.2 Further Examination and TreatmentSubsequently, relevant laboratory tests were conducted. We found that the patient’s hypoglycemic symptoms tend to occur during fasting, with blood glucose levels below 2.2 mmol/L and insulin levels significantly elevated above the normal range. The symptoms were alleviated following intravenous glucose injection.Given that his hypoglycemic episodes are frequent and life-threatening, laparoscopic pancreatic tumor resection was performed in March 2025. A solid mass measuring approximately 2 cm in diameter was identified in the body of the pancreas and resected carefully without pancreatic Injury (Figure 2).3.3 PathologyPostoperative pathology revealed neuroendocrine tumor (NET G2) without vascular or neural invasion (The maximum diameter of the mass was 2 cm). Immunohistochemistry results: Pan-CK、CD56、CgA、Syn、E-cad、INSM1(+), SSTR2、Vimentin (-), P53( suggestive of a wild-type genotype ), β-Catenin (+)，CD10 ( small partially + ), CK19 ( partially + ), CAM5.2 ( partially + ), CK7、LEF-1、CK20、SATB2、CDX-2 (-), Ki-67 ( index 5% ) (Figure 3).Notes:“+” = positive; “−” = negative; “partially +” = focal/partial positivity; “index X%” = labeling index (proportion of positive cells).4 Outcome and Follow-UpThe patient had an uncomplicated postoperative course. Postoperative continuous blood glucose monitoring indicated that the patient’s levels remained consistently within the normal range, with no recurrence of hypoglycemic symptoms. Upon follow-up evaluation, the patient had resumed a regular diet and exhibited no weight loss or deterioration in functional status. The patient has not experienced any further behavioral abnormalities, sudden loss of consciousness, or hypoglycemic symptoms and is now able to carry out normal daily activities and work.5 DiscussionNeuroendocrine tumors (NETs) arise from neuroendocrine cells, which are ubiquitously distributed throughout the body. Common primary sites include the lung, pancreas, and gastrointestinal tract [8]. Pancreatic neuroendocrine tumors (PanNETs) are rare neoplasms, with an incidence of