What does IPMN (Intraductal Papillary Mucinous Neoplasm) stand for?

IPMN Definition

IPMN stands for Intraductal Papillary Mucinous Neoplasm. 1

What IPMN Represents

IPMNs are pathologically defined as mass-forming pre-invasive neoplasms (tumoral intraepithelial neoplasms) that grow within the ducts of the pancreas. 2

Key Pathological Characteristics

• IPMNs show papillary epithelial proliferation within dilated pancreatic ducts filled with mucin. 1

• These lesions are characterized by mucin-producing epithelial cells with excessive mucus production and cystic dilatation of the pancreatic ducts. 3

• IPMNs must be greater than 1 cm in diameter to distinguish them from incidental microcysts and large pancreatic intraepithelial neoplasms (PanINs). 2

Clinical Spectrum

• IPMNs encompass a spectrum ranging from innocuous-appearing lesions (formerly called "hyperplasia") to full-blown intramucosal carcinomatous lesions (formerly designated as "papillary adenocarcinoma"). 2

• The progression follows an adenoma-carcinoma sequence: low-grade dysplasia → intermediate-grade dysplasia → high-grade dysplasia → invasive carcinoma. 2

• IPMNs can progress to invasive carcinoma of different types (ductal/tubular or colloid/muconodular) with variable extent. 2

Classification Types

• IPMNs are classified into four main cell types: gastric, intestinal, oncocytic, and pancreatobiliary, each with distinct morphological characteristics. 4

• Anatomically, IPMNs are classified as branch duct type, main duct type, or mixed type based on the site of tumor involvement. 5