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Liver and intrahepatic bile ducts - Tumor

Benign tumors

Focal nodular hyperplasia (FNH)


Reviewers: Deepali Jain, M.D. (see Reviewers page)
Revised: 13 May 2013, last major update February 2012
Copyright: (c) 2004-2013, PathologyOutlines.com, Inc.

General
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● Common benign mass with an indolent course (#2 liver tumor after hemangioma); no known malignant potential
● Usually an incidental finding; present in 1% of autopsies
● Median age 38 years; F:M ratio varies from 8-12:1
● Represents 2-10% of pediatric hepatic tumors; never reported in elderly
● May be associated with oral contraceptives (66-95% of cases), hepatic cavernous hemangioma (20%), glycogen storage disease type Ia, portal hypertension
● Tumors associated with oral contraceptives often have hemorrhage, necrosis, infarction
● May have abdominal discomfort, pain, anorexia or fatigue (Hepatobiliary Pancreat Dis Int. 2004;3:199)
● Telangiectatic FNH are monoclonal and more closely resemble hepatic adenomas than classical FNH

Etiology
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● May represent hyperplastic response to preexisting arterial malformation or other vascular anomaly; is NOT a neoplasm (Am J Gastroenterol 2006;101:2341)


Diagram of possible pathogenesis

Case reports
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● 13 month old girl (Case of the Week #88)

Radiology decription
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● Mass with central scar, centrifugal hypervascularity by angiography
● CT and MRI are important, but often cannot make a definite preoperative diagnosis (Hepatobiliary Pancreat Dis Int 2007;6:52)

Treatment
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● Excellent prognosis
● Adult women should discontinue oral contraceptives, if applicable
● Surgery if symptomatic, complications, compression of adjacent organs or lesion progression (Eur J Pediatr Surg 2006;16:235)

Gross description
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● Well demarcated, nonencapsulated, subcapsular, light brown to yellow (lighter than surrounding liver)
● Bulging nodule, 70-80% solitary, up to 5 cm; rarely > 10 cm
● Central gray-white stellate scar (unless < 1 cm) from which fibrous septa radiate to periphery and create multiple smaller nodules
● Hemorrhage, necrosis, infarction, bile staining often seen; larger tumors may have multiple scars; adjacent liver is normal

Gross images
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Well circumscribed mass with central stellate scar


Asymptomatic left lobe liver mass

Micro description
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● Most tumors (80%) have 3 classic features: abnormal architecture, bile ductular proliferation, malformed vessels
● Hepatocyte nodules are surrounded by fibrous septa with large malformed arterial branches not accompanied by interlobular bile ducts or portal veins
● Typically void of any formal portal triads
● Septal margins have foci of intense lymphocytic infiltrates and marked bile duct proliferation with histologic changes of chronic cholestasis (Mallory’s hyaline, bile pigment, copper deposits, pseudoxanthomatous change), variable neutrophilic infiltration
● Ductules appear to arise from limiting plate; central scar contains central fibrous body with tortuous large vessels with fibromuscular hyperplasia and luminal narrowing
● Hepatic plates are 1-2 cells thick, similar to surrounding liver, but may be larger and paler with fat or glycogen
● No atypia, no mitotic figures
● Non-classic forms lack either abnormal architecture or malformed vessels, and are devoid of central scar
● 3 types: (a) telangiectatic, (b) mixed hyperplastic and adenomatous, (c) atypia of large cell (Am J Surg Pathol 1999;23:1441)
● Telangiectatic variant: multiple dilated vascular channels in center of mass; considered by some to be a variant of hepatic adenoma (World J Gastroenterol 2007;13:2649)
● Mixed hyperplastic and adenomatous: contain regions resembling telangiectatic and hepatic adenoma
● Atypia of large cell: atypical hepatocytes with enlarged hyperchromatic nuclei with irregular contours frequently demonstrating cytoplasmic–nuclear inclusions

Micro images
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Fibrous area with blood vessels and bile ductules


Associated with fibrolamellar carcinoma




Asymptomatic left lobe liver mass

Positive stains
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● Alpha-1-antitrypsin

Negative stains
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● p53, CD143 (angiotensin I-converting enzyme: reduced expression, Am J Surg Pathol 2004;28:84)

Differential diagnosis
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● Osler-Weber-Rendu disease, Budd-Chiari syndrome or cirrhosis (adjacent liver is not normal), fibrolamellar hepatocellular carcinoma (marked atypia of hepatocytes), hepatocellular adenoma (encapsulated, monoclonal), peritumoral hyperplasia (Arch Pathol Lab Med 2000;124:1105)

Additional references
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Radiographics 2004;24:3, eMedicine


Multiple focal nodular hyperplasia syndrome

General
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● Multiple FNH lesions plus one other lesion: either hepatic hemangioma, arterial dysplasia, Klippel-Trenaunay-Weber syndrome, Turner's syndrome, brain telangiectasia, berry aneurysm, astrocytoma or meningioma

Micro description
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● Often telangiectatic variant with multiple dilated vascular channels in center of mass

End of Liver and intrahepatic bile ducts - Tumor > Benign tumors > Focal nodular hyperplasia (FNH)


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