Mucin-hypersecreting tumors of the pancreas: Assessing the grade of malignancy preoperatively

Background Mucin-hypersecreting tumor of the pancreas (MHST) is a unique variant of pancreatic tumor, where mucin was excreted from the patulous orifice of the enlarged ampulla of Vater and the main pancreatic duct was dilated with excessive mucin. It is difficult to differentiate preoperatively between benign and malignant variants. Patients and methods A total of 18 patients with an MHST were retrospectively reviewed to identify possible indicators of malignancy. The 18 tumors consisted of 9 benign lesions (hyperplasia or adenoma with mild to moderate atypia), 2 borderline disorders (adenoma with severe atypia), and 7 malignant diseases (unequivocal adenocarcinoma). Results The age, sex, and site of origin demonstrated no significant difference among the three groups. One of the 9 patients with the benign lesion was diabetic, while 4 of the 7 patients with the malignant variant were diabetic (P<0.05). All 9 benign lesions were confined to the side branch, while 4 of the 7 malignant diseases were located in the main pancreatic duct (P<0.05). The mean greatest diameters of these three variants were 3.2 cm, 3.3 cm, and 6.6 cm, respectively. The mean greatest diameter of the main pancreatic duct in the 7 malignant disorders were larger than in the 9 benign conditions (9.7 versus 5.4 mm, P<0.05). The mean diameter of the mural nodules in the 7 malignant tumors were larger than in the 9 benign lesions (20.5 versus 5.1 mm, P<0.05). The serum and mucin carcinoembryonic antigen and carbohydrate antigen 19-9 levels showed no substantial difference between the benign and malignant variants. Conclusions The presence of diabetes, large tumors (≥5 cm), marked dilatation of the main pancreatic duct (≥10 mm), main pancreatic duct type, and large mural nodules (≥10 mm) is strongly suggestive of a malignant variant of the MHST.