From the Guidelines
Malignant degeneration of Intraductal Papillary Mucinous Neoplasms (IPMN) on Computed Tomography (CT) imaging refers to the progression of a benign IPMN to a malignant pancreatic tumor, often characterized by enhancing solid components, main pancreatic duct dilatation, and/or lymphadenopathy 1, 2, 3.
Key Features of Malignant Degeneration
- Main pancreatic duct dilatation: a diameter of ≥10 mm is highly predictive of malignancy 1, 2
- Enhancing mural nodule: a size of ≥5 mm is highly predictive of malignancy 1, 2
- Solid component: highly predictive of malignancy 1, 2
- Jaundice: highly predictive of malignancy 1, 2
- Positive cytology: highly predictive of malignancy 1, 2 ### Management of Malignant IPMN Management of malignant IPMN typically involves surgical resection 1, 2, although in select cases, neoadjuvant chemotherapy with agents such as gemcitabine and nab-paclitaxel for 3-6 months may be considered to downstage the tumor 1, 2.
Surveillance and Follow-up
Patients with IPMN without indication for surgery should be followed up until they are no longer fit for surgery, as the risk of IPMN progression increases over time 4.
Risk Factors for Malignant Degeneration
- Cyst size: a diameter of ≥40 mm is associated with an increased risk of high-grade dysplasia or cancer 1, 2
- Growth rate: a growth rate of ≥5 mm/year is associated with an increased risk of high-grade dysplasia or cancer 1, 2
- Serum CA 19.9: elevated levels (>37 U/mL) are associated with an increased risk of malignancy 1, 2
From the Research
Definition and Classification of Intraductal Papillary Mucinous Neoplasms (IPMNs)
- IPMNs are characterized by the papillary growth of the ductal epithelium with rich mucin production, leading to cystic segmental or diffuse dilatation of the main pancreatic duct (MPD) and/or its branches 5.
- They are classified into three types: main duct type (MD-IPMN), branch duct type (BD-IPMN), and mixed type (MT-IPMN) 6, 5.
Malignant Degeneration of IPMNs
- MD-IPMNs and MT-IPMNs harbor a high risk of malignant degeneration, requiring resection in most cases 7.
- The presence of solid nodules, thick enhancing walls and/or septae, a wide (> 1 cm) connection of a side-branch lesion with the MPD, and the size of the tumor > 3 cm are indicative of malignancy in branch and mixed type IPMNs 6.
- A main pancreatic duct > 6 mm, a mural nodule > 3 mm, and an abnormal attenuating area in the adjacent pancreatic parenchyma on CT correlate with malignant disease in main duct and mixed type IPMNs 6.
Computed Tomography (CT) Imaging of IPMNs
- CT imaging is used to assess the risk of malignant degeneration in IPMNs, with features such as solid nodules, thick enhancing walls, and septae being indicative of malignancy 6, 8.
- The size of the tumor, the presence of a wide connection with the MPD, and the presence of mural nodules are also important factors in assessing the risk of malignant degeneration on CT imaging 6, 8.
Risk Assessment and Management of IPMNs
- The management of IPMNs depends on the distinction between benign and invasive forms, assessment of malignancy risk, patient's wellness, and preferences 5.
- The choice between non-operative and surgical management depends on the type of IPMN, with MD-IPMNs and MT-IPMNs requiring resection in most cases, while BD-IPMNs can be safely surveilled in most cases 7, 5.