Liver & intrahepatic bile ducts
Vascular disorders
Sinusoidal obstruction syndrome

Topic Completed: 1 February 2018

Revised: 24 January 2019, last major update February 2018

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Sinusoidal obstruction syndrome[TI] liver

Raul S. Gonzalez, M.D.
Page views in 2019: 968
Page views in 2020 to date: 1,066
Cite this page: Gonzalez R. Sinusoidal obstruction syndrome. website. Accessed September 19th, 2020.
Definition / general
Essential features
  • Form of sinusoidal injury first described in Jamaican bush tea drinkers; now usually occurs following hematopoietic stem cell transplant (J Clin Exp Hepatol 2014;4:332)
ICD coding
  • Toxic agent damages sinusoidal endothelial cells, likely via depletion of glutathione and nitric oxide
  • Injury related sloughing of sinusoidal endothelial cells leads to embolic sinusoidal obstruction around central veins
  • Hepatocytes also injured, contributing to disease process
  • First described in Jamaica, where the causative agent was imbibed bush tea
  • Now seen primarily in stem cell transplant patients, secondary to alkylating myeloablative drugs (cyclophosphamide, etc.)
  • Other causative agents include chemotherapy drugs such as oxaliplatin
Diagrams / tables

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Hepatic acinus

Clinical features
  • Occurs after a few weeks in up to 25% of patients receiving allogeneic bone marrow transplant; biopsy is risky in these patients
  • Leads to mortality in 40% of patients; worse if multiple organ failure also occurs (J Med Econ 2017;20:871)
  • Acute symptoms include marked weight gain, tender hepatomegaly, ascites and jaundice
  • Portal hypertension may occur
  • ‚Ä®Rarely progresses to cirrhosis
  • Increase in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) with little change in alkaline phosphatase (ALP)
Radiology images

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Sinusoidal obstruction syndrome

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Patchy liver enhancement

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Hepatic sinusoidal obstruction syndrome after ingestion of Gynura segetum

Case reports
Gross description
  • Liver may appear blue if a resection or autopsy case is received
Microscopic (histologic) description
  • Acutely, hemorrhage into markedly dilated sinusoids with hepatocyte atrophy; sinusoids are denuded, though this may be difficult to see clearly
  • Later, some regions of liver heal while others show collapse; constriction / obliteration of small central veins by subendothelial swelling / fibrosis can be seen
  • Sinusoidal fibrosis and nodular regeneration may occur
Microscopic (histologic) images

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Images contributed by Raul S. Gonzalez, M.D.:

Acute disease, with sinusoidal hemorrhage

Chronic disease, with shrunken central vein

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Acute congestion

Vein narrowing

Trichrome showing obliterated vein

Fibrous occlusion
of centrilobular
venule (silver stain)

Positive stains
  • Trichrome stain may be necessary to observe scant evidence of completely obliterated central veins
Electron microscopy description
  • Sinusoidal obstruction syndrome (SOS): a light and electron microscopy study in human liver (Micron 2016;84:17)
Differential diagnosis
  • Budd-Chiari syndrome: different clinical scenario / presentation; sinusoids may be dilated but not denuded; central veins should not show collapse
  • Sickle cell disease: red blood cells filling sinusoids appear sickled on high power
Board review style question #1
53 year old man with leukemia undergoes myeloablative therapy and allogeneic stem cell transplant. One week later, he presents with jaundice, hepatomegaly and weight gain. Which of the following would be the most likely finding on liver biopsy?

  1. Bile duct injury
  2. Cytomegalic inclusions
  3. Hepatic artery obliteration
  4. Massive sinusoidal dilation
  5. Mixed portal inflammation
Board review answer #1
D. Massive sinusoidal dilation
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