From the Guidelines
Intraductal Papillary Mucinous Neoplasm (IPMN) of the pancreas is a type of pancreatic cyst that forms in the ducts of the pancreas and produces mucin, a thick fluid, with main duct IPMNs carrying a higher risk of malignancy compared to branch duct IPMNs.
Definition and Classification
IPMNs are characterized by papillary growths within the pancreatic ducts and can range from benign to malignant. They are classified based on their location: main duct, branch duct, or mixed type. The classification of IPMNs is crucial in determining the risk of malignancy and guiding management decisions 1.
Risk of Malignancy
Main duct IPMNs have a higher risk of malignancy, with a risk of around 62% 1, compared to branch duct IPMNs, which have a lower risk of malignancy. The risk of malignancy in IPMNs is influenced by various factors, including the size of the cyst, the presence of solid components, and the degree of dysplasia 1.
Management
Management of IPMNs depends on the risk of malignancy and the patient's overall health. High-risk IPMNs typically require surgical resection, while lower-risk lesions may be monitored with regular imaging. The decision between surgery and surveillance should be individualized based on the patient's age, comorbidities, and the specific characteristics of the IPMN 1.
- Absolute indications for surgery include:
- Positive cytology for malignancy or high-grade dysplasia
- Solid mass
- Jaundice (tumor-related)
- Enhancing mural nodule (≥5 mm)
- Main pancreatic duct dilatation ≥10 mm
- Relative indications for surgery include:
- Growth rate ≥5 mm/year
- Increased levels of serum CA 19-9 (>37 U/mL)
- Main pancreatic duct dilatation between 5 and 9.9 mm
- Cyst diameter ≥40 mm
- New-onset diabetes mellitus
- Acute pancreatitis (caused by IPMN)
- Enhancing mural nodule (<5 mm)
Follow-up
Regular follow-up is essential even for low-risk IPMNs due to their potential for malignant transformation over time. The frequency and modality of follow-up imaging should be individualized based on the patient's risk factors and the characteristics of the IPMN 1. The most recent and highest quality study 1 recommends resection in fit patients with main duct IPMNs ≥10 mm, and surveillance is considered an appropriate option in patients who are older or unfit or for cysts lacking high-risk stigmata.
From the Research
Definition and Classification of IPMN
- Intraductal Papillary Mucinous Neoplasm (IPMN) of the pancreas is a noninvasive epithelial neoplasm of mucin-producing cells arising in the main duct and/or branch ducts of the pancreas 2.
- IPMNs are divided into three types: main duct-IPMN (MD-IPMN), branch duct-IPMN (BD-IPMN), and mixed type-IPMN 3.
- IPMNs can be classified into low-grade, intermediate-grade, and high-grade dysplasia based on cytoarchitectural atypia 2.
- Based on histological features and mucin (MUC) immunophenotype, IPMNs are classified into gastric, intestinal, pancreatobiliary, and oncocytic types 2.
Clinical Features and Diagnosis
- IPMNs are usually diagnosed at the age of 60-70 years and affect men and women equally 4.
- The characteristic imaging features include a cystic lesion with associated dilatation of the main or branch pancreatic duct, and atrophy of surrounding pancreatic parenchyma 4.
- Magnetic resonance imaging is the most useful for most IPMNs 3.
- Cytomorphological features of IPMN include papillary fragments of mucinous epithelium in a background of abundant thick extracellular mucin 4.
Management and Prognosis
- Management depends on the type and radiological features of IPMNs 3.
- Surgery is recommended for MD-IPMN, while management of BD-IPMN involves surgery or surveillance depending on the tumor size, cyst growth rate, solid components, main duct dilatation, high-grade dysplasia in cytology, the presence of symptoms, and CA 19.9 serum level 3.
- The prognosis of IPMN is excellent, but critically worsens when invasive carcinoma arises 2, 5.
- Postoperative surveillance is required for resected IPMNs 4.