Differentiation Syndrome

Synonyms: Diffrentiation Syndrome, Retinoic Acid Syndrome, ATRA Syndrome.


  • Retinoic acid syndrome (RAS) is a potentially life-threatening complication observed in patients with acute promyelocytic leukemia (APML)
  • It is named because it is first thought to be specifically associated with all-trans retinoic acid (ATRA) treatment.
  • Subsequently it was found out that similar symptops may appear in APML patients who had been treated with arsenic trioxide, and yet did not appear in patients treated with tretinoin for other disorders. These facts and others support the notion that RAS depends on the presence of the malignant promyelocytes. Due to this reason it is now termed as ‘Differentiation syndrome’ to signify this APML treatment complication.


Clinical Presentation:

  • Dyspnea,
  • Fever,
  • Weight gain,
  • Hypotension,
  • Pulmonary infiltrates.


Management: This is effectively treated by giving dexamethasone and holding ATRA (or arsenic trioxide) in severe cases. An elevated white count is sometimes associated with this syndrome, but is not a prerequisite.



Radiological Findings:


Plain film

Although X ray features are not specific, they may aid in early recognition of the ATRA syndrome. Most important features are

  • increased cardiothoracic ratio
  • increased vascular pedicle width
  • ground-glass opacities
  • peribronchial cuffing
  • septal lines and
  • pleural effusion(s)

In addition, chest radiography may show nodules and consolidation.


X Ray Show cardiomegaly and multiple lung infiltrates.

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