Liver and intrahepatic bile duct

Question 1

Liver with atypical hepatocytes forming trabeculae, pseudoglands, solid, and macrotrabecular (thickened plates) architecture, lacking portal triads (‘unpaired arteries’) and invading adjacent cirrhotic liver

Answer 1

Hepatocellular carcinoma

Differential diagnosis
Hepatocellular adenoma (if well differentiated)
Intrahepatic cholangiocarcinoma
Metastatic carcinoma

Plan:
Correlate with clinical history and radiology (?liver disease, e.g. hepatitis, alcohol, cirrhosis etc)
Examine further blocks (e.g. for size, relation to margins, areas of differing morphology)
Special stains: Reticulin (highlight thickened plates or loss of framework)
IPX to support Dx: Hepar1, Arginase1 (hepatocellular origin). HSP70, glypican-3 and glutamine synthetase (support malignancy)
IPX to discount DDx: CK7 and 20
Next steps: Synoptic report, discuss at MDT

Question 2

Liver lesion with cords and nests of large oncocytic hepatocytes with open chromatin and macronucleoli. Cells are seperated by dense collagen bundles arranged in parallel lamellae. Can sometimes see calcification.

Answer 2

Fibrolamellar variant of hepatocellular carcinoma

Differential diagnosis:
Focal nodular hyperplasia

Plan:
Correlate with clinical history and radiology
Examine further sections (e.g. for size, relation to margins)
IPX to support Dx: Hepar1, CK7, CD68
IPX to discount DDx: GS
Molecular (not needed for diagnosis): DNAJB1-PRKACA fusion
Next steps: Synoptic report, discuss at MDT
Advice to clinician: May be sporadic or assiociated with Carney complex. Clinical correlation is required. Has propensity for late recurrence.

Question 3

Liver lesion with broad anastomosing vascular channels which form cystic spaces

Answer 3

Cavernous hemangioma of liver

Plan:
Correlate with clinical history and radiology
Examine further sections (e.g. for size, areas of differing morphology)
IPX to support Dx: Not required
No specific action required for this benign diagnosis

Question 4

Liver parenchyma with large ‘blood lakes’ (blood filled cystic spaces without endothelial lining) and background sinusoidal dilation

Answer 4

Peliosis hepatitis

Plan:
Correlate with clinical history and radiology (?drug exposures ?HIV)
Advice to clinician: May be associated with drug exposure or Bartonella infection in HIV+ patients.

Question 5

Liver lesion with central scar radiating fibrous septa that separate nodules of bland hepatocytes in sinusoids of normal thickness. The central scar contains abnormally thick walled vessels, and fibrous septa show an inflammatory infiltrate and surrounding bile ductular reaction. Hepatocytes adjacent to septa also show features of cholestasis (feathery degeneration and Mallory-Denk bodies).

Answer 5

Focal nodular hyperplasia

Differential diagnosis:
Hepatocellular adenoma (e.g inflammatory type)
Fibrolamellar variant of hepatocellular carcinoma

Plan:
Correlate with clinical history and radiology (?Oral contraceptive use)
Examine further blocks (e.g. for size of lesion, relation to margins, areas of differing morphology)
IPX to support Dx: Glutamine synthetase (expect ‘map-like’ staining)
IPX to discount DDx: CRP and SAA, CK7 and CD68
No specific further action required for this benign diagnosis.