Fukuoka consensus guidelines

Fukuoka consensus guidelines, also referred to as the Tanaka criteria, is a classification system for intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs). 

The prior international consensus guidelines (2006) were referred to as the Sendai criteria, which later evolved into the Fukuoka consensus guidelines (2012) ¹ with the latest update published in 2017 ³. 

Contrast-enhanced CT and MRI have been shown to have comparable diagnostic performance for the diagnosis of malignant IPMN. 

Investigation

• cyst <5 mm
  • asymptomatic: invasive carcinoma is rare if the patient is asymptomatic, therefore, follow-up only is recommended
  • symptomatic: further evaluation or resection (clinical circumstances dictate)
• cyst >5 mm
  • pancreatic protocol CT or MRI pancreas and MRCP to evaluate

Classification

• branch duct IPMN (BD-IPMN)
  • cyst >5 mm communicating with main duct
• main duct IPMN (MD-IPMN)
  • higher frequency of malignancy
  • dilatation of the main duct > 5 mm without other cause for obstruction
    • 5-9 mm: "worrisome feature"
    • ≥10 mm: "high-risk stigmata"
• mixed-type IPMN: appears like an advanced branch duct IPMN with main pancreatic duct dilatation (>5 mm)
  • higher frequency of malignancy, similar to the main duct type

High-risk stigmata

• enhancing solid component >5 mm
  • strongest association with malignant IPMN ⁴
• main pancreatic duct ≥10 mm
• obstructive jaundice

Worrisome features

• cyst ≥3 cm
• thickened and enhancing cyst wall
• enhancing mural nodule <5 mm
• main pancreatic duct 5-9 mm
• lymphadenopathy
• abrupt change in calibre of the pancreatic duct with distal pancreatic atrophy
• cyst growth rate ≥5 mm in two years
• elevated CA 19-9

Pathology

Histological subclassification

• gastric-type: the majority of BD-IPMNs
• intestinal-type
• pancreaticobiliary-type
• oncocytic-type

Treatment and prognosis

• resection
  • all main duct IPMNs
  • all other IPMNs with high-risk stigmata
  • all mucinous cystic neoplasms
• endoscopic ultrasound (EUS)
  • cysts with worrisome features
  • all cysts ≥3 cm without worrisome features
    • if inconclusive, then close surveillance with alternating MRI and EUS every 3-6 months
    • strongly consider surgery in young patients

Cyst fluid analysis is optional in a centre with expertise in EUS fine-needle aspiration.

Surveillance

Optimal imaging surveillance strategies for suspected BD-IPMNs <3 cm and without worrisome features is unclear, but the yearly incidence of transformation to pancreatic cancer is estimated at 0.4-1.1% per year:

• largest cyst <1 cm: CT or MRI/MRCP in 6 months, then every 2 years if no change
• largest cyst 1-2 cm: CT or MRI/MRCP 6 monthly for 1 year, then yearly for 2 years, then lengthen interval up to 2 years if no change
• largest cyst 2-3 cm: EUS in 3-6 months, then lengthen interval up to 1 year alternating MRI with EUS as appropriate
  • consider surgery in young patients, with a need for prolonged surveillance

NB The American Gastroenterological Association recommends stopping surveillance after 5 years if no significant change is observed or if a cyst is resected and found to be benign ². This is not a recommendation that is explicitly stated in the Fukuoka 2017 update ³.