Groove pancreatitis
Overview
- Rare focal form of chronic pancreatitis centred in the pancreaticoduodenal groove (space between pancreatic head, duodenum, and common bile duct)
- Characterised by fibrotic scarring ± cystic change in groove or duodenal wall
- Two forms:
- Pure: confined to groove
- Segmental: involves groove and adjacent pancreatic head
- Strong association with alcohol abuse and smoking
- Frequently mimics pancreatic head ductal adenocarcinoma
Epidemiology
- Predominantly middle-aged males (40–60 years)
- Heavy alcohol consumption almost universal risk factor
- Rare overall, but increasingly recognised on imaging
Key radiological manifestations
CT (modality of choice)
- Ill-defined sheet-like soft-tissue mass or fibrosis in pancreaticoduodenal groove
- Poorly enhancing relative to normal pancreas
- Cystic foci within groove or duodenal wall (highly characteristic)
- Duodenal wall thickening with luminal narrowing/stenosis
- Smooth tapering of intrapancreatic common bile duct (no abrupt cutoff)
- Minimal or no upstream pancreatic duct dilatation
- Delayed venous phase: gradual enhancement of fibrotic tissue
MRI
- T1WI: hypointense sheet-like tissue in groove
- T2WI: variable – cysts hyperintense, fibrosis hypointense
- Post-contrast: delayed enhancement similar to CT
- MRCP: tapered narrowing of distal CBD and main pancreatic duct without significant upstream dilatation
Endoscopic ultrasound
- Useful adjunct: hypoechoic groove mass, cysts in thickened duodenal wall
Classic signs
Sheet-like groove fibrosis + cysts in duodenal wall/medial aspect + duodenal stenosis → virtually pathognomonic for groove pancreatitis.
Differential diagnosis
| Diagnosis | Key differentiators |
|---|---|
| Pancreatic ductal adenocarcinoma | Discrete mass, abrupt duct cutoff, upstream dilatation >5 mm, vascular invasion, metastases |
| Autoimmune pancreatitis | Sausage-shaped pancreas, capsule-like rim, multifocal IgG4 disease, steroid response |
| Acute pancreatitis | Peripancreatic fluid/stranding, clinical acute onset |
| Duodenal carcinoma | Primary duodenal mass, mucosal irregularity, lymphadenopathy |
| Paraduodenal fibrosis (other causes) | No cysts in duodenal wall, different clinical context |
Common pitfall
Segmental form with head involvement often mistaken for carcinoma → leads to unnecessary Whipple resection. Look carefully for duodenal wall cysts and absence of abrupt duct obstruction.
Imaging approach
- Initial: multiphase contrast-enhanced CT (arterial + pancreatic + venous phases)
- Equivocal cases → MRI with MRCP for better soft-tissue and duct characterisation
- EUS ± biopsy if carcinoma cannot be excluded (histology shows Brunner gland hyperplasia, fibrosis, cysts)
- Follow-up: conservative management (alcohol cessation) often leads to stabilisation or improvement
Pearls
- Cystic change within thickened medial duodenal wall or groove is the most specific finding
- Absence of vascular encasement and metastases favours groove pancreatitis over malignancy
- Smooth tapering of CBD and pancreatic duct without marked upstream dilatation strongly against carcinoma
- Alcohol history + male patient + groove-centred findings → think groove pancreatitis first
- Pure form rarely causes significant head mass effect
Reporting tip
Suggest "features consistent with groove pancreatitis (sheet-like fibrosis with duodenal wall cysts and smooth distal CBD tapering); clinical correlation and consider EUS to exclude malignancy."
