The differences in imaging features of malignant and benign branch duct type of Intraductal Papillary Mucinous Tumor

Objective: To investigate the difference in the radiological features of malignant and benign branch duct type of IPMT (Intraductal Papillary Mucinous Tumor) of the pancreas. Methods: Thirty-six patients who were referred for operation with branch duct type of IPMT of the pancreas were included in this study. All cases underwent both CT and MRI with contrast enhancement. The size of the cystic lesions, the presence and size of mural nodules, and the amount of dilatation of the MPD were assessed by two independent radiologists, and the results were compared with pathological findings. Results: Histological examination revealed adenoma in 8 cases, AH (atypical hyperplasia) in 8 cases, CIS (carcinoma in situ) in 8 cases and invasive carcinoma in 12 cases. Patients of the malignant group were older than those in the benign group (mean age: 67 yrs vs 60 yrs, respectively), but no statistically significant (p = 0.05). Males (16/4 vs 10/6) more often complained weight loss and jaundice. The malignant tumor was more frequently located in the head-body and body. Compared with the benign group, the mean sizes of the cyst, mural nodules, MPD of the malignant group were 44 mm, 13 mm, 7.5 mm and benign group were 31 mm, 5 mm, 3.5 mm respectively. All these difference are statistically significant (p < 0.05). In 4 cases of the 20 in the malignant group, soft tissue suggesting spread of disease into the adjacent viscera and peritoneum was detected. Conclusion: Cyst size over 30 mm and mural nodule over 8 mm, irregular thick septa, dilatation of the MPD, and accompany with soft tissue mass may be helpful factors in determining malignancy.