IPMN - Imaging features and management

 Intraductal mucinous papillary neoplasm of the pancreas (IPMN):

 Imaging features and management

Fig 1. T2 W high TE MRCP of three different patients demonstrates 3 types of IPMN. Yellow arrows point the main pancreatic duct and red arrows point to side branch dilatation.

Definitions:

- IMPN develops in the main pancreatic duct or side branches

- Pathologically, these are "papillary proliferation "  of mucin producing epithelial cells with various degrees of dysplasia

- Secretes excessive amounts of mucin and are cystic

- 5th decade / men / more in head

- Precursors of cancer

Types:

1. Main pancreatic duct (MD-IPMN)

2. Side branch (BD- IPMN)

3. Mixed (MT-IPMN)

Histologic subtypes:

- Gastric (usually of mid grade)

- Intestinal

- Pancreatico-biliary

- Oncocytic

Grades of dysplasia & invasive carcinoma:

- Mild dysplasia

- Moderate dysplasia

- High grade dysplasia / ca in-situ (not considered as malignant, but is an indication of surgery

- Invasive cancer

Diagnostic Algorithm:

1. MRCP & MRI pancreas with and without gadolinium

2. Endoscopic ultrasound - more sensitive to detect malignancy

Red flags  (Fukoka classification):

1. high risk Stigmata - main pancreatic duct > 10 mm

                                    - enhancing mural nodule> 5 mm

                                    - Leading to jaundice, when in head

2. Worrisome           - main pancreatic duct 5 - 9 mm

                                  - enhancing mural nodule < 5 mm

                                  - Cyst size > 3 cm

                                   - growth of > 5 mm in 2 years

                                  -  lymphadenopathy

                                  - Abrupt change in the diameter of PD and distal atrophy

                                  - increased serum ca 19-9

                                  - Clinical sign of pancreatitis

                                  - Contrast enhancement

Management (Fukoka guidelines)

High risk stigmata / main duct type- resection in a fit patient

Worrisome / side branch- Follow up

< 1 cm - CT / MRI 6 months fu - thereafter, every 2 years

< 2 cm - CT / MRI 6 months fu - thereafter, every 1 year and lengthen to 2 year or more

2-3 cm - EUS 3 to 6 months fu - thereafter, lengthen every 1 year alternate with MRI. Consider surgery for young and fit

> 3 cm - EUS/MRI 3 to 6 months fu - Consider surgery for young and fit

Important points:

- Mixed types or multifocal are most challenging  for treatment

- Despite negative margins 20 % patients may develop pancreatic ca in remnant pancreas "metachronous cancer"

- Concomitant separate pancreatic ca seen in 2 to 10 %

- High grade dysplasia is an indication of surgery

- Mucinous cystic neoplasm (MCN) is a separate category from IPMN (MCN is mucin producing columnar epithelium with ovarian stroma and occur in the body and tail & seen in middle aged women)

Prepared by Dr. Sharad Maheshwari

02.12.2022

Updated: 31.12.2022

References:

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548937/

2. https://www.karger.com/Article/Fulltext/370111

3. https://www.endoscopy-campus.com/en/classifications/impn-fukuoka-classification-guidelines/