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Liver and intrahepatic bile ducts - Tumor

Benign tumors

Bile duct adenoma / Atypical bile duct adenoma


Reviewers: Deepali Jain, M.D. (see Reviewers page)
Revised: 9 January 2013, last major update February 2012
Copyright: (c) 2004-2013, PathologyOutlines.com, Inc.

General
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● Benign, but not a true neoplasm
● Incidental finding, although often confused with adenocarcinoma
● Currently regarded as a peribiliary gland hamartoma or a localized reactive ductular proliferation due to previous unknown injury
● Usually adults (age range 1-99 years), no gender preference
● Much less common than bile duct hamartoma/von Meyenburg complex

Gross description
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● Well-circumscribed but unencapsulated, firm, gray-white, tan or yellow, subcapsular round to oval nodules; 85% solitary
● May have central depression
● Usually 5 mm or less but 7% are larger than 1 cm (0.5cm to 1.5cm)
● Larger than von Meyenburg complex and smaller than cholangiocarcioma;

Micro description
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● Compact network of simple noncystic tubular ducts or more complex tortuous arrangement, with small or indistinct lumina
● Epithelium has abundant cytoplasm and pale nuclei compared to interlobular bile ducts in adjacent liver
● Rarely clear and oncocytic cells (Histopathology 2006;49:318)
● Variable fibrous stroma
● Center of larger lesions is paucicellular, densely collagenised; nodular lymphoid aggregate at periphery
● Non caseating granulomas, microcalcification, inflammatory cells; normal portal tracts with bile ducts may be present
● Usually no cystic change, no cytoplasmic or intraluminal bile, no atypia, no mitotic figures, no angiolymphatic invasion

Positive stains
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● Mucin (intracytoplasmic), CEA, EMA, keratin, PAS highlights basement membrane

Differential diagnosis
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● Adenocarcinoma: atypical cytologic and architectural features
Cholangiocarcioma: larger, infiltrative
von Meyenburg complex: 0.5cm or smaller, less cellular, curvilinear angulated inspissated bile containing ducts, more abundant stroma


Atypical bile duct adenoma, clear cell type

General
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● Rare; ages 25-63 years in 3 cases described (Am J Surg Pathol 2001;25:956)
● Incidental finding
● Cytoplasmic clearing may be due to accumulation of fat, acid mucin, or distended endoplasmic reticulum

Gross description
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● 1 cm, subcapsular

Micro description
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● Bile duct tumor composed almost entirely of small nests and tubules of clear cells infiltrating hepatic parenchyma by involving entrapped normal bile ducts; small nests surrounded by PAS+ membrane (may represent tubular structures)
● Well-defined cytoplasmic borders, mild nuclear hyperchromasia, mild stromal sclerosis; no mitotic activity

Positive stains
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● CK7, EMA, CEA, p53, mucin (focal)

Negative stains
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● CK20, vimentin, HepPar1, chromogranin, Ki-67 (<10% positive)

Differential diagnosis
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Clear cell cholangiocarcinoma: larger, tubular pattern, desmoplastic stroma, more nuclear atypia increase mitotic activity and elevated Ki-67 labeling index; similar immunostains results
Metastatic renal cell carcinoma
● Well-differentiated adenocarcinoma

End of Liver and intrahepatic bile ducts - Tumor > Benign tumors > Bile duct adenoma


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