Differentiation syndrome and Sweet’s syndrome: is there a connection?

Links checked 19/02/18.

Is there a connection between differentiation syndrome and Sweet’s syndrome?

By February 2015, only three cases of Sweet’s syndrome had been reported in patients with differentiation syndrome which occurred as a result of treatment with all trans-retinoic acid (ATRA) for acute promyelocytic leukaemia (Salono-Lopez et al, 2015).

What is acute promyelocytic leukaemia?

Acute promyelocytic leukaemia (APL) is a form of blood cancer that affects a type of white blood cell called the myeloid cell. It’s more common in older than younger adults, and is rare in young children.

What is differentiation syndrome?

Differentiation syndrome, formally known as retinoic acid syndrome, is a potentially life-threatening condition that mainly occurs as a result of treatment with ATRA or arsenic trioxide for APL. It occurs in approximately 25% of patients with APL receiving these treatments during induction therapy – the first phase of chemotherapy where the aim is to get rid of as many leukaemia cells as possible.

What are the symptoms of differentiation syndrome?

Symptoms of differentiation syndrome include fever; low blood pressure; shortness of breath; weight gain of more than 5 kg; abnormal findings in the lungs on chest x-ray or scan (Montesinos and Sanz, 2011). Less common and rare symptoms include swollen feet and ankles as a result of fluid building up in the tissues; bone, muscle or nerve pain; Sweet’s syndrome; kidney or liver problems; fluid around the heart.

Can ATRA therapy also cause Sweet’s syndrome?

Yes. In 5-12% of cases, Sweet’s syndrome can be triggered by medication (drug-induced). The most common medication is G-CSF (granulocyte-colony stimulating factor), but it can also be triggered by other medications, including ATRA. The reason as to why some medications can trigger Sweet’s syndrome is still poorly understood, but may be a hypersensitivity reaction.

Is there a connection between differentiation syndrome and Sweet’s syndrome?

Possibly. There is debate over whether or not differentiation syndrome and Sweet’s syndrome are completely separate conditions or are part of the same disease spectrum. This is because they share some common features. These include fever, white blood cells called neutrophils infiltrating the tissues, and improvement after steroid therapy. However, there are also some differences. Unlike in differentiation syndrome, Sweet’s syndrome doesn’t commonly affect internal organs, and isn’t associated with capillary leak syndrome. This is a rare and life-threatening condition that has been suggested as a potential cause for differentiation syndrome. It causes endothelial cells lining small blood vessels called capillaries to separate, allowing fluid to leak into the space between the cells. This eventually leads to symptoms such as a rapid drop in blood pressure; shock; sudden swelling of the arms or legs, and other parts of the body; lightheadedness; weakness; fatigue; feeling sick; fluid around the heart and lungs; high percentage of red blood cells in the blood; low levels of protein in the blood.


Montisenos, P. and Sanz, M. (2011) The Differentiation Syndrome in Patients with Acute Promyelocytic Leukemia: Experience of the Pethema Group and Review of the Literature. Mediterranean Journal of Hematology and Infectious Diseases, Dec;3(1):e2011059 (PMC).

Solano-López, G., Llamas-Velasco, M., Concha-Garzón, M. and Daudén, E. (2015) Sweet syndrome and differentiation syndrome in a patient with acute promyelocytic leukemia. World Journal of Clinical Cases, Feb 16;3(2):196-8 (PMC).

2012-2018 Sweet’s Syndrome UK


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