Liver & intrahepatic bile ducts

Other malignancies

Hepatic small vessel neoplasm

Editorial Board Member: Monika Vyas, M.D.
Deputy Editor-in-Chief: Aaron R. Huber, D.O.
Josef G. Venable, M.D.
Annika L. Windon, M.D.

Last author update: 8 June 2023
Last staff update: 8 June 2023

Copyright: 2021-2023,, Inc.

PubMed Search: Hepatic small vessel neoplasm

Josef G. Venable, M.D.
Annika L. Windon, M.D.
Page views in 2022: 181
Page views in 2023 to date: 827
Cite this page: Venable JG, Windon AL. Hepatic small vessel neoplasm. website. Accessed September 30th, 2023.
Definition / general
  • Rare, recently described vascular hepatic neoplasm of uncertain malignant potential that is composed of anastomosing, densely packed, small, thin vessels with infiltrative borders, minimal cytologic atypia and a low proliferative rate
Essential features
  • Hepatic small vessel neoplasm that shares similar morphologic and molecular qualities to and is thought to represent anastomosing hemangioma of the liver
  • Histologically described as benign, low grade hepatic vascular neoplasm with a mottled, unencapsulated gross appearance with poorly circumscribed borders
  • Positive for vascular markers with frequent GNAQ mutations
  • Hepatic small vessel neoplasm (HSVN)
  • Anastomosing hemangioma (AH)
ICD coding
  • ICD-10: D37.6 - neoplasm of uncertain behavior of liver, gallbladder and bile ducts
  • Has morphologic and molecular similarities to and may represent anastomosing hemangioma of the liver
Clinical features
  • Histopathologic diagnosis: infiltrative small vessel vascular neoplasm with mild nuclear atypia and low proliferative index
  • Diagnosis can be supported by immunohistochemistry and molecular testing
  • Normal complete blood count (CBC), serum chemistry, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alpha fetoprotein (AFP), carcinoembryonic antigen (CEA) and CA19-9 (BMJ Case Rep 2022;15:e248785)
Radiology description
  • CT with contrast: hypodense lesions with contrast enhancement in the arterial and portal phase and wash out in the tardive phase
  • PET / CT: no evidence of abnormal 18F fluorodeoxyglucose (18F FDG) uptake
  • MRI with contrast: atypical vascular tumor with strong and early rim enhancement in arterial phase, with central irregular morphology and gradual enhancement (BMJ Case Rep 2022;15:e248785)
Radiology images

Contributed by Carlo M. Cicala, M.D.

Abdominal CT

Abdominal MRI

Prognostic factors
Case reports
  • Complete resection and close clinical follow up is recommended due to the unknown longterm behavior of this neoplasm (Hum Pathol 2016;54:143)
Gross description
  • Poorly circumscribed, unencapsulated, pale tan to brown hemorrhagic lesions with ill defined borders
  • Size ranges from < 1 cm to > 15 cm
  • No grossly apparent cystic spaces or vessels (Hum Pathol 2016;54:143)
Gross images

Contributed by Ryan M. Gill, M.D.

Tan-brown, unencapsulated, mottled tumor

Microscopic (histologic) description
  • Anastomosing, closely packed, small thin vascular channels lined by flat to plump endothelial cells with occasional hobnailing
  • Infiltrative border with extension between hepatic plates and around portal tracts
  • Minimal cytologic atypia
  • Absence of necrosis, mitotic activity, prominent nucleoli, nuclear pleomorphism
  • Occasional extramedullary hematopoiesis, hyaline globules and vascular thrombi
  • Reference: Hum Pathol 2016;54:143
Microscopic (histologic) images

Contributed by Ryan M. Gill, M.D.

Infiltrating small vessels

Extramedullary hematopoiesis (megakaryocyte)

Densely packed infiltrative vessels

Reticulin stain

CD31 IHC stain

ERG IHC stain

CD34 IHC stain


Ki67 in hepatic angiosarcoma

Positive stains
Negative stains
Molecular / cytogenetics description
  • Recurrent activating hotspot mutations of GNAQ, GNA11 and GNA14
    • Not found in angiosarcoma
    • Recorded in several other vascular lesions: capillary hemangioma, angioma variants, hemangioendothelioma
  • Activating hotspot mutation in PIK3CA
    • Also found in angiosarcoma
  • Reference: Hum Pathol 2016;54:143
Sample pathology report
  • Liver, excision:
    • Hepatic small vessel neoplasm, 2.5 cm (see comment)
    • Comment: The Ki67 proliferative index is approximately 6%. Surgical margins are negative for tumor.

  • Liver, biopsy:
    • Vascular neoplasm with nuclear atypia (see comment)
    • Comment: A neoplastic process consisting of back to back small vessels with mild nuclear atypia is identified. Ki67 immunohistochemical stain highlights ~5% of the endothelial nuclei. Although definitive infiltrative architecture is not present in this sample, these findings are most consistent with the recently described entity hepatic small vessel neoplasm.
Differential diagnosis
Board review style question #1

A 2.5 cm liver lesion was incidentally identified on a CT scan of a 55 year old man with no significant medical history. No other lesions are identified radiographically. A core biopsy is performed revealing an infiltrative neoplasm pictured above. ERG is positive while HepPar1 and HHV8 are negative and p53 shows wild type staining. What molecular abnormality would most likely be identified in this neoplasm?

  1. GNAQ hotspot mutation
  2. KDR mutation
  3. MYC amplification
  4. RAS mutation
  5. TP53 mutation
Board review style answer #1
A. GNAQ hotspot mutation. The H&E photomicrograph shows a neoplasm consisting of small vessels with unremarkable endothelial cells, infiltrating between hepatic plates, consistent with a hepatic small vessel neoplasm (HSVN). HSVNs (and benign vascular neoplasms such as hemangiomas) are associated with hotpot mutations in the GNAQ family of genes. The other answer choices are mutations commonly identified in hepatic angiosarcoma (Hum Pathol 2022;29:300671).

Comment Here

Reference: Hepatic small vessel neoplasm
Back to top
Image 01 Image 02