Branch duct intraductal papillary mucinous tumors (IPMTs) are increasingly being described and represent a challenge for the physician. Recent imaging modalities, especially computed tomography and magnetic resonance, allow for a correct diagnosis, but IPMTs can manifest with different degrees of cellular atypia so it is very important to be able to establish the biological behavior of the lesion. Sixty-five patients were included in this study: 29 of them underwent surgery, and the other 36 were followed with cross-sectional imaging. Among patients who underwent surgery, 11 had benign lesions and 18 had malignant lesions. Overall sensitivity, specificity, and accuracy in the diagnosis of malignancy for all the cross-sectional imaging techniques were 61%, 81%, and 69%, respectively. Among patients who were followed and had a magnetic resonance cholangiopancreatographic diagnosis of branch duct IPMT with imaging features indicative of benignity, only two showed modifications over the follow-up period. Even considering some important biases (small number of patients and relatively short follow-up), interesting conclusions can be drawn: the imaging diagnosis of malignancy can be trusted, whereas that of benignity cannot be relied upon, but if the signs of malignancy are absent, the slow growth of the lesions justifies watchful follow-up in the correct clinical setting.