Liver & intrahepatic bile ducts

Benign / nonneoplastic

Bile duct adenoma



Last author update: 16 June 2023
Last staff update: 16 June 2023

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PubMed Search: Bile duct adenoma

Komal Ijaz, M.D.
Feng Yin, M.D., Ph.D.
Page views in 2023: 12,640
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Cite this page: Ijaz K, Yin F. Bile duct adenoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/livertumorbileductadenoma.html. Accessed February 22nd, 2024.
Definition / general
  • Bile duct adenoma is a benign biliary neoplasm consisting of uniformly distributed small bile ducts in a background of fibrotic stroma
Essential features
  • Benign epithelial tumor
  • Most commonly a solitary subcapsular nodule (90%)
  • Frequently an incidental finding at surgery or autopsy
  • Frequently submitted for frozen section to rule out metastatic process
  • Can be difficult to distinguish from adenocarcinoma, especially on frozen section
  • Uniform distribution of small tubules with no cytological atypia or mitotic figures
  • Frequent BRAF V600E mutation supports a neoplastic process
Terminology
  • Also known as peribiliary gland hamartoma, cholangioma, cholangioadenoma
ICD coding
  • ICD-O: 8160/0 - bile duct adenoma
  • ICD-11: 2E92.7 & XH6KR6 - benign neoplasm of liver or intrahepatic bile ducts & bile duct adenoma
Epidemiology
  • Usually adults (age > 20), no gender predilection
  • Accounts for 1.3% of primary liver tumors and 2.4% in a total of 1,456 resection cases for primary liver tumors and explant for liver cirrhosis (Am J Surg Pathol 1988;12:708, Pathol Int 2014;64:551)
Sites
  • Liver, typically subcapsular location
Pathophysiology
Etiology
  • Unknown; whether focal injury acts as trigger event remains controversial
Clinical features
  • Mostly an incidental finding during surgery or autopsy
  • Frequently submitted for frozen section to rule out metastatic process
Diagnosis
  • Clinical presentation and histopathologic findings
Radiology description
  • Hypointense on T1 weighted images, hyperintense on T2 weighted images
  • Characteristic arterial phase hyperenhancement that persists into the portal venous and delayed phases on CT and MRI (Diagn Interv Radiol 2018;24:249)
Prognostic factors
Case reports
Gross description
  • Usually subcapsular, well circumscribed but nonencapsulated
  • Majority are solitary but can be multiple
  • Firm, gray-white
  • Size ranging from 1 to 20 mm (mean: 5.8 mm) (Am J Surg Pathol 1988;12:708)
Gross images

Images hosted on other servers:

Well circumscribed
nonencapsulated
subcapsular lesion

Frozen section description
  • Usually solitary subcapsular lesion, well circumscribed and nonencapsulated
  • Bland small tubular proliferation in a background of fibrotic stroma
  • Lack of marked nuclear atypia, mitotic figures, necrosis or intraluminal bile
  • Potential diagnostic pitfalls: cellular stroma, back to back compact architecture, mucin production, unusual variant (oncocytic, clear cell, etc.), cytologic atypia enhanced by frozen section artifact
Frozen section images

Contributed by Feng Yin, M.D., Ph.D.
Well circumscribed unencapsulated lesion

Well circumscribed unencapsulated lesion

Lack of atypical features

Lack of atypical features

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Komal Ijaz, M.D. and Feng Yin, M.D., Ph.D.
Well circumscribed unencapsulated lesion

Well circumscribed unencapsulated lesion

Subcapsular well circumscribed lesion

Subcapsular well circumscribed lesion

Tubules with fibrous stroma

Tubules with fibrous stroma

Tubules with focal crowding

Tubules with focal crowding


Tubules with bland cytology Tubules with bland cytology

Tubules with bland cytology

Tubules with cytoplastic mucin

Tubules with cytoplastic mucin

Fine needle biopsy Fine needle biopsy

Fine needle biopsy

Cytology description
Positive stains
Molecular / cytogenetics description
  • Majority of bile duct adenomas are positive for albumin in situ hybridization, a feature that distinguishes it from metastatic pancreatic adenocarcinoma (Histopathology 2016;69:423)
Sample pathology report
  • Liver, wedge biopsy:
    • Intrahepatic bile duct adenoma (see comment)
    • Comment: The biopsy demonstrates the proliferation of small tubules with no cytological atypia embedded in the fibrous stroma, consistent with bile duct adenoma.
Differential diagnosis
Board review style question #1

A 55 year old man with pancreatic adenocarcinoma was admitted for Whipple procedure. A small liver nodule was noted during surgery and sent for intraoperative consultation. A representative photomicrograph of the frozen section is shown. Which of the following is the most likely diagnosis?

  1. Bile duct adenoma
  2. Metastatic pancreatic adenocarcinoma
  3. Reactive ductular proliferation
  4. Von Meyenburg complex
Board review style answer #1
A. Bile duct adenoma. The diagnosis of a bile duct adenoma is favored during intraoperative consultation, largely attributed to the presence of uniform distribution of small tubules in a background of fibrous stroma. There are no worrisome morphological features, such as infiltrative growth pattern, desmoplastic stromal reaction, marked cytological atypia, frequent mitosis and necrosis.

Comment Here

Reference: Bile duct adenoma
Board review style question #2
Which gene is most frequently mutated in bile duct adenoma?

  1. BRAF
  2. KRAS
  3. p53
  4. SMAD4
Board review style answer #2
A. BRAF mutations are present in about 53% of bile duct adenomas.

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Reference: Bile duct adenoma
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