Gallbladder & Biliary Pathology

The hepatobiliary "stone-to-cancer" axis is a NEET PG favourite: gallstones drive cholecystitis, chronic inflammation drives metaplasia and carcinoma, while the autoimmune cholangiopathies (PSC, PBC) carry their own near-pathognomonic antibody and association pairings. This note ties the morphology, antibodies, imaging and management together.

Overview & orientation

Biliary pathology spans three buckets that examiners love to mix:

1. Stone disease — cholelithiasis → cholecystitis (acute/chronic) → complications.
2. Autoimmune cholangiopathies — primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC).
3. Neoplasia — carcinoma gallbladder and cholangiocarcinoma.

High-yield: The two single most-tested associations in this topic are PSC ↔ ulcerative colitis + p-ANCA + beaded ducts and PBC ↔ anti-mitochondrial antibody (AMA) + middle-aged woman + granulomatous bile-duct destruction. Lock these first.

Cholelithiasis (gallstones)

Gallstones form when bile becomes lithogenic — supersaturated with cholesterol or unconjugated bilirubin, with stasis and a nidus for nucleation. Three pathogenic pillars: supersaturation, hypomotility (stasis), nucleation/mucus hypersecretion.

Types of gallstones

Feature	Cholesterol stones	Black pigment stones	Brown pigment stones
Major component	Cholesterol monohydrate (>50%)	Calcium bilirubinate (polymerised)	Calcium bilirubinate + fatty acid soaps
Colour/number	Pale yellow, often solitary/large	Black, small, multiple, spiculated	Brown, laminated, soft, greasy
Radio-opacity	Usually radiolucent (10–20% opaque)	Radio-opaque (~50–75%)	Radiolucent
Setting	Chronic haemolysis of cholesterol metabolism: obesity, female, fertile, fifties, OCPs, rapid weight loss, ileal disease	Chronic haemolysis (sickle cell, thalassaemia, hereditary spherocytosis), cirrhosis	Infection/stasis of biliary tree — E. coli, Ascaris, Clonorchis; mostly intrahepatic in Asia
Location	Gallbladder	Gallbladder (sterile bile)	Bile ducts (infected bile)

High-yield: Brown pigment stones = the only stone forming in infected/obstructed ducts; classically with parasites (Clonorchis sinensis, Ascaris) in Asian populations. Black pigment stones = sterile bile + chronic haemolysis.

Risk factors mnemonic — the 6 Fs: Female, Fat, Fertile, Forty, Fair, Family history. Add rapid weight loss/bariatric surgery, terminal ileal Crohn's (bile-salt malabsorption), OCP/oestrogen, and cirrhosis.

Cholesterol lithogenesis flow: Oestrogen/obesity → ↑ hepatic cholesterol secretion + ↓ bile acids → supersaturated bile → gallbladder hypomotility (stasis) → mucin glycoprotein nucleation → microcrystals → macroscopic stone.

High-yield: Most gallstones are radiolucent (cholesterol), so plain X-ray misses ~85%. Ultrasound is the investigation of choice for cholelithiasis (sensitivity >95%; mobile echogenic focus with posterior acoustic shadowing).

Acute cholecystitis

Acute inflammation of the gallbladder, >90% caused by stone impaction in the cystic duct/Hartmann's pouch (calculous). The remaining acalculous cases occur in critically ill, ICU, post-trauma, burns, TPN, sepsis patients (ischaemia + stasis) and carry higher mortality.

Pathophysiology

Cystic duct obstruction → bile stasis + concentrated bile → mucosal injury by lysolecithin and bile salts → wall oedema, prostaglandin-mediated inflammation → secondary bacterial invasion (E. coli, Klebsiella, Enterococcus).

Clinical features

• Right hypochondrial pain (>6 h, unlike biliary colic which is <6 h), fever, leucocytosis.
• Murphy's sign: inspiratory arrest on deep palpation of the RUQ — sensitive for acute cholecystitis.
• Boas sign: referred hyperaesthesia at the right inferior scapular angle.

Diagnosis

• USG first-line: wall thickening >3 mm, pericholecystic fluid, distended GB, sonographic Murphy's sign, impacted stone.
• HIDA scan = most specific test: non-visualisation of gallbladder at 60 min (cystic duct blocked) confirms acute cholecystitis. Reserved when USG equivocal.

Test	Best for	Key positive finding
USG	First-line, stones	Wall >3 mm, pericholecystic fluid, sonographic Murphy
HIDA (cholescintigraphy)	Most specific for acute cholecystitis	GB non-visualisation at 60 min
MRCP	CBD stones / ductal anatomy	Filling defect, ductal dilation
ERCP	Therapeutic CBD clearance	Stone extraction + sphincterotomy

High-yield: Laparoscopic cholecystectomy within 72 hours (early) is the management of choice for acute calculous cholecystitis. For unfit/critically ill patients with acalculous disease → percutaneous cholecystostomy drainage.

Morphology

Enlarged, tense, fiery-red/blotchy-violaceous GB; fibrinous/suppurative exudate. Severe forms: empyema (pus-filled), gangrenous cholecystitis, emphysematous cholecystitis (gas-forming Clostridium/E. coli, diabetics — surgical emergency), and perforation.

Chronic cholecystitis

The commonest form, almost always with stones. Repeated low-grade inflammation/subclinical attacks. Morphology: thickened fibrotic wall, Rokitansky–Aschoff sinuses (herniations of mucosal epithelium through the muscularis — outpouchings), chronic inflammatory infiltrate.

• Porcelain gallbladder: dystrophic mural calcification from chronic inflammation. Historically high cancer association; now considered a moderate risk — prophylactic cholecystectomy still advised, especially selective/incomplete mucosal calcification pattern.
• Xanthogranulomatous cholecystitis: lipid-laden macrophages, mimics carcinoma on imaging.
• Strawberry gallbladder (cholesterolosis): cholesterol-laden macrophages in lamina propria producing yellow mucosal speckling — usually incidental, not true cholecystitis.

High-yield: Rokitansky–Aschoff sinuses = chronic cholecystitis. Porcelain gallbladder = calcified wall + carcinoma risk → operate.

Primary sclerosing cholangitis (PSC)

Chronic, progressive fibrosing inflammation of intra- AND extra-hepatic bile ducts, leading to multifocal strictures and biliary cirrhosis.

• Demographics: middle-aged men (M:F ~2:1).
• Association: ulcerative colitis (~70–80% of PSC have IBD, mostly UC). Conversely only ~5% of UC patients get PSC. Course of PSC is independent of colitis activity and may progress after colectomy.
• Serology: p-ANCA (atypical/perinuclear) positive in ~65–80%. AMA negative.
• Cholangiography (MRCP/ERCP) — diagnostic: "beaded" appearance — alternating strictures and dilatations; "pruned tree" intrahepatic ducts.
• Histology: "onion-skin" periductal concentric fibrosis with duct obliteration; relatively non-specific on biopsy, so imaging is key.

High-yield: PSC = man + UC + p-ANCA + beaded ducts + onion-skin fibrosis. Major dreaded complication = cholangiocarcinoma (lifetime risk 10–15%). Also ↑ colorectal cancer risk in PSC-UC → annual colonoscopy surveillance.

Management: No proven disease-modifying drug; liver transplantation is the only definitive therapy for end-stage disease. Ursodeoxycholic acid improves biochemistry but not survival (high-dose harmful). Endoscopic dilation/stenting for dominant strictures.

Primary biliary cholangitis (PBC)

Formerly "primary biliary cirrhosis." Autoimmune granulomatous destruction of small/medium INTRAhepatic bile ducts (interlobular). Extrahepatic ducts are spared.

• Demographics: middle-aged women (F:M ~9:1), 40–60 years.
• Serology: anti-mitochondrial antibody (AMA), specifically anti-PDC-E2 (M2) — positive in ~90–95% and highly specific. ↑ serum IgM.
• Clinical: insidious fatigue and pruritus, then jaundice; xanthelasma/xanthomas (hypercholesterolaemia), hepatomegaly, osteoporosis/osteomalacia (fat-soluble vitamin malabsorption). Strong association with Sjögren syndrome, Hashimoto thyroiditis, scleroderma/CREST, RA.
• Biochemistry: cholestatic pattern — markedly ↑ alkaline phosphatase and GGT, with relatively preserved transaminases.
• Histology: florid duct lesion — granulomatous destruction of bile ducts with lymphocytic infiltrate; bile duct loss → ductopenia → biliary cirrhosis.

High-yield: PBC = woman + AMA (anti-M2) + ↑ ALP + intrahepatic granulomatous duct destruction + pruritus. First-line drug = ursodeoxycholic acid (UDCA), which does improve survival in PBC (contrast with PSC). Second-line: obeticholic acid (FXR agonist).

PSC vs PBC — the table examiners want

Feature	PSC	PBC
Sex predilection	Men	Women
Ducts involved	Intra + extra-hepatic	Small intra-hepatic only
Antibody	p-ANCA (AMA −)	AMA / anti-M2 (~95%)
Key association	Ulcerative colitis	Sjögren, Hashimoto, CREST
Cholangiogram	Beaded strictures	Normal large ducts
Histology	Onion-skin periductal fibrosis	Florid duct lesion (granulomatous)
Major cancer risk	Cholangiocarcinoma + colorectal	Hepatocellular carcinoma (cirrhotic)
Disease-modifying Rx	Transplant (UDCA no benefit)	UDCA improves survival

Mnemonic: "PBC = Pretty Big Concentration of AMA in women; PSC = Strictures, Sclerosing, men, UC."

Carcinoma of the gallbladder

Most common biliary tract malignancy; adenocarcinoma in >90%. Female predominance, peaks in 6th–7th decade. Notably more common in North India (Gangetic belt) — a frequently tested epidemiological point.

Risk factors

• Gallstones (cholelithiasis) — present in ~75–90%; large stones (>3 cm) carry highest risk.
• Porcelain gallbladder, chronic cholecystitis, chronic typhoid carriage (Salmonella typhi — "Typhoid Mary"), gallbladder polyps >1 cm.
• Anomalous pancreaticobiliary duct junction (APBDJ) with reflux.

Clinical & spread

Often silent; presents late mimicking chronic cholecystitis, or with weight loss, jaundice, palpable mass. Fundus is the commonest site. Direct spread to liver (segments IVb/V) and early lymphatic spread → poor prognosis. Courvoisier's law (palpable non-tender GB + painless jaundice) classically points to periampullary/pancreatic head malignancy obstructing the CBD, not GB cancer itself.

High-yield: Strongest GB-cancer risk factor in PYQs = gallstones, especially large (>3 cm). The "salmonella chronic carrier" link and North Indian female epidemiology are repeat items.

Spread/investigation flow: Suspicious wall thickening on USG → contrast CT/MRI for staging → tissue diagnosis. Treatment: radical cholecystectomy (with liver bed + lymphadenectomy) only if early/resectable; most present late with dismal 5-year survival.

Cholangiocarcinoma (brief)

Adenocarcinoma of bile duct epithelium. Klatskin tumour = perihilar tumour at the junction of right/left hepatic ducts (commonest type) — causes obstructive jaundice with a non-dilated GB. Risk factors: PSC, choledochal cysts, Caroli disease, liver flukes (Clonorchis, Opisthorchis), hepatolithiasis, thorotrast. Marker: CA 19-9.

Complications of stone disease (named)

• Choledocholithiasis → obstructive jaundice; ascending cholangitis → Charcot triad (fever + RUQ pain + jaundice); Reynold pentad adds hypotension + altered sensorium (suppurative cholangitis — emergency ERCP).
• Gallstone ileus: large stone erodes through into duodenum via cholecysto-enteric fistula → impacts at ileocaecal valve. Rigler triad: pneumobilia + small-bowel obstruction + ectopic gallstone.
• Mirizzi syndrome: stone in Hartmann's pouch/cystic duct externally compresses the common hepatic duct → jaundice.
• Gallstone pancreatitis: stone impacted at ampulla of Vater.
• Empyema, gangrene, perforation → biliary peritonitis.

High-yield: Charcot triad → cholangitis; Reynold pentad → suppurative cholangitis; Rigler triad → gallstone ileus; Mirizzi → cystic-duct stone compressing CHD. These four named clusters are extremely high-recall.

Key differentials

• RUQ pain: acute cholecystitis vs biliary colic (pain <6 h, no fever) vs peptic ulcer vs hepatitis vs right basal pneumonia.
• Cholestatic jaundice: PBC vs PSC vs drug-induced cholestasis vs extrahepatic obstruction (stone/tumour).
• GB wall thickening: chronic cholecystitis vs adenomyomatosis vs xanthogranulomatous cholecystitis vs carcinoma.
• Positive AMA + cholestasis = PBC until proven otherwise; p-ANCA + IBD + beaded ducts = PSC.

Recently asked / exam angle

• Antibody matching: "AMA positive cholestatic disease in a woman" → PBC; "p-ANCA + UC + beaded ducts" → PSC. Single most repeated theme.
• Brown pigment stones with infected bile/parasites vs black pigment with haemolysis — direct one-liner MCQs.
• HIDA non-visualisation = acute cholecystitis (most specific test).
• Rokitansky–Aschoff sinuses as the buzzword for chronic cholecystitis.
• Onion-skin fibrosis (PSC) vs florid duct lesion / granulomatous destruction (PBC) histology pairing.
• Largest GB-cancer risk = large gallstones (>3 cm); Salmonella chronic carrier link.
• UDCA improves survival in PBC but not PSC — a classic differentiator.
• Named triads/pentads (Charcot, Reynold, Rigler) as image/clinical-vignette items.
• Strawberry gallbladder = cholesterolosis; porcelain gallbladder = calcified, prophylactic cholecystectomy.

Rapid revision

1. USG = investigation of choice for gallstones and acute cholecystitis; most stones are radiolucent.
2. HIDA non-visualisation of GB at 60 min = most specific for acute cholecystitis.
3. Cholesterol stones: female/fat/fertile/forty, radiolucent, solitary. Black pigment: haemolysis. Brown pigment: infected ducts/parasites.
4. Rokitansky–Aschoff sinuses = chronic cholecystitis morphology.
5. PSC = man + UC + p-ANCA + beaded ducts + onion-skin fibrosis; complication = cholangiocarcinoma; Rx = transplant.
6. PBC = woman + AMA(anti-M2) + ↑ALP + granulomatous intrahepatic duct destruction + pruritus; Rx = UDCA (improves survival), then obeticholic acid.
7. UDCA helps survival in PBC, not PSC.
8. GB carcinoma: adenocarcinoma, North Indian female, gallstones (>3 cm) strongest risk, Salmonella carrier, porcelain GB.
9. Klatskin tumour = perihilar cholangiocarcinoma; marker CA 19-9; risk = PSC, choledochal cyst, liver flukes.
10. Charcot triad = cholangitis; Reynold pentad = suppurative cholangitis; Rigler triad = gallstone ileus; Mirizzi = cystic-duct stone compressing CHD.
11. Murphy's sign positive in acute cholecystitis; Courvoisier's law (painless palpable GB) points to periampullary/pancreatic cancer.
12. Early laparoscopic cholecystectomy (<72 h) for acute calculous cholecystitis; percutaneous cholecystostomy for unfit/acalculous patients.