Chronic pancreatitis — diagnosis, mechanism and management viva

Interpretation

The examiner presents an abdominal CT of a cachectic middle-aged man showing a shrunken, atrophic pancreas with multiple intraductal calcific stones, a dilated and irregular main pancreatic duct, and a small pseudocyst in the head. "What is the diagnosis, what is the underlying mechanism, and how would you manage this patient's pain and his exocrine and endocrine failure?"

• Diagnosis: chronic pancreatitis (CP), calcifying form, almost certainly alcoholic in this demographic; the irreversible calcification, ductal change and atrophy distinguish it from acute pancreatitis.^[1][2]

Key points

The examiner will probe each of these; be ready to defend them at viva depth:

1. Definition and distinction from acute pancreatitis — progressive, fibrotic, inflammatory disease producing irreversible morphological damage with permanent loss of exocrine and endocrine function; contrast with the reversibility of mild AP.
2. Aetiology — TIGAR-O (Toxic-metabolic, Idiopathic, Genetic, Autoimmune, Recurrent/severe AP, Obstructive); alcohol 60 to 70 percent, tobacco an independent co-factor; tropical calcific in southern India; hereditary PRSS1.^[2]
3. Mechanism — the pancreatic stellate cell (PSC) is the central effector. Quiescent vitamin-A-storing periacinar cells are activated by alcohol, acetaldehyde, oxidative stress and cytokines (TGF-beta, PDGF, IL-1, TNF-alpha) into myofibroblasts that deposit collagen types I and III — producing fibrosis, acinar loss and ductal distortion. Four parallel mechanisms generate pain: ductal hypertension, parenchymal/compartment hypertension, perineural inflammation (increased nerve density, perineural immune infiltrate, nerve growth factor), and ischaemia.^[2]
4. Functional loss — steatorrhoea appears only when lipase secretion falls below 10 percent of normal (over 90 percent acinar reserve lost); type 3c diabetes is brittle and hypoglycaemia-prone because both insulin (beta-cell) and glucagon (alpha-cell) are lost.
5. Diagnosis — combination of imaging and function. Faecal elastase under 200 microg/g (under 100 severe; not affected by PERT); AXR/CT pancreatic calcification (pathognomonic); CT ductal change and atrophy graded by Cambridge (mild/moderate/marked); MRCP/EUS (Rosemont) for early disease; 'chain of lakes' on ERCP.
6. Pain — tiered pathway. Tier 1: alcohol + smoking cessation, PERT (negative-feedback CCK effect), small frequent low-fat meals, stepwise analgesia (paracetamol → NSAID → tramadol → strong opioid; pethidine NOT preferred), neuromodulators. Tier 2: endoscopic — ESWL for stones over 5 mm, sphincterotomy, stricture stenting. Tier 3: surgical — Puestow (lateral pancreaticojejunostomy) for duct over 7 mm; Beger/Frey/Whipple for inflammatory head mass; TPIAT for intractable small-duct disease.
7. PERT dosing — pancreatin (Creon) 25,000 to 40,000 units lipase per main meal, 10,000 to 25,000 with snacks, with a PPI (protect enzymes from gastric acid); taken WITH food, throughout the meal.
8. Type 3c diabetes — insulin (often low doses); avoid sulfonylureas (hypoglycaemia) and GLP-1 agonists (pancreatitis concern).
9. Autoimmune pancreatitis — 'sausage' pancreas, capsule-like rim, painless jaundice, raised IgG4, other-organ involvement; HISORt criteria; prednisolone 40 mg daily then taper — the steroid-responsive mimic of pancreatic cancer.
10. Complications — pseudocyst, biliary stricture, splenic vein thrombosis with isolated gastric varices (splenectomy curative), visceral pseudoaneurysm (catastrophic bleed — angiography and embolisation), pancreatic cancer (cumulative risk about 4 percent at 20 years).
11. Evidence — ANTICIPATE (Siriwardena 2012) showed antioxidants do NOT reduce pain in CP, refuting routine antioxidant use.^[6]
12. Pitfalls — never miss pancreatic cancer (re-evaluate any change); never label CP without considering autoimmune pancreatitis; never forget splenic vein thrombosis in gastric-variceal bleeding; never over-prescribe opioids without a pain-service plan.

References3ShowHide

1. [1]Majumder S, Chari ST. Chronic pancreatitis. Lancet, 2016.PMID 26948434
2. [2]Kleeff J, Whitcomb DC, Shimosegawa T, et al. Chronic pancreatitis. Nature Reviews Disease Primers, 2017.PMID 28880010
3. [6]Siriwardena AK, Mason JM, Sheen AJ, et al. Antioxidant therapy does not reduce pain in patients with chronic pancreatitis: the ANTICIPATE study. Gastroenterology, 2012.PMID 22683257