Necrotizing Sweet’s Syndrome

Updated 19/11/18.

Sometimes, Sweet’s syndrome can occur in an unusual form. This is known as a disease variant.

Necrotizing Sweet’s syndrome.

Necrotizing Sweet’s syndrome (NSS) is a rare variant of Sweet’s syndrome that mimics both the skin and systemic symptoms of necrotizing fasciitis (NF) (Sanchez et al, 2018).

What is necrotizing fasciitis?

NF is a rare and serious bacterial infection that affects the superficial fascia – a layer of connective tissue that lies beneath the skin and between the muscles and organs in the body. NF not only causes inflammation and damage to the fascia, but also the tissues next to it. Toxins made by the bacteria then destroy soft-tissue, causing it to die. This is known as soft-tissue necrosis.

What is necrotizing Sweet’s syndrome?

NSS is an acute necrotizing form of neutrophilic dermatosis that not only causes skin lesions, the most common symptom of Sweet’s syndrome, but also affects the deeper tissues and causes soft-tissue necrosis.

What are the symptoms?

NSS symptoms include:

  • Fever.
  • Low blood pressure.
  • Skin lesions.
  • Pathergy – when the skin is damaged and it triggers the development of new skin lesions or makes existing ones worse.
  • Severe pain.

Read more here.

How is necrotizing Sweet’s syndrome diagnosed?

NSS is mainly diagnosed via biopsy. A sample of a lesion shows white blood cells called neutrophils in the deep tissues, but unlike in Sweet’s syndrome, soft-tissue necrosis also occurs. Fever and low blood pressure in NSS can be misdiagnosed as sepsis – a serious complication of infection – with NF (Nakanishi and Kinjo, 2016).

How is it treated?

The treatment for NSS and NF is very different, so it’s important that the two conditions are not confused, misdiagnosis increasing the likelihood of unnecessary surgical procedures and prolonged illness, at the very least (Sanchez et al, 2018). The main form of treatment for NSS is intravenous (IV) steroids, whereas NF is treated with IV antibiotics and wound debridement – surgical removal of the infected tissue. Antibiotics don’t work in the treatment of NSS, and wound debridement must be avoided due to a pathergy response.

Cases of necrotizing Sweet’s syndrome.

Some reported cases of NSS include:

  • 3 patients with very weakened immune systems that initially appeared to be septic, and demonstrated pathergy (Kroshinsky et al, 2012).
  • 73-year-old man with chronic myeloid leukaemia who was initially diagnosed with NF and systemic inflammatory response syndrome – an inflammatory state that affects the whole body, often in response to infection, but not always (Nakanishi and Kinjo, 2016).
  • 24-year-old transsexual male with recurrent myonecrosis of the neck and upper chest, initial findings suggesting a necrotizing soft tissue infection affecting the muscle (Otero et al, 2017).
  • A case after elective hand surgery (Lipof et al, 2017).


Can patients with Sweet’s syndrome, but not necrotizing Sweet’s syndrome, sometimes develop symptoms that mimic necrotizing fasciitis?

Yes, paraneoplastic fasciitis can be a symptom of Sweet’s syndrome, and is sometimes confused with NF (Chaudhry et al, 2015: 128-129).

What is paraneoplastic fasciitis?

Paraneoplastic fasciitis is a type of fasciitis that develops alongside cancer. It causes inflammation and thickening of the fascia, but unlike in NF, soft-tissue necrosis does not occur. In patients with Sweet’s syndrome who develop paraneoplastic fasciitis, skin lesions are normally present, but not always. On occasion, inflammation of the fascia can be a symptom of Sweet’s syndrome, even when someone doesn’t have cancer.


Chaudhry, A., Baker, K., Gould, E. and Gupta, R. (2015) Necrotizing fasciitis and its mimics: what radiologists need to know. American Journal of Roentgenology, Jan;204(1):128-39 (online).

Kroshinsky, D., Alloo, A., Rothschild, B., Cummins, J., Tan, J., Montecino, R., Hoang, M., Duncan, L., Mihm, M. and Sepehr, A. (2012) Necrotizing Sweet syndrome: a new variant of neutrophilic dermatosis mimicking necrotizing fasciitis, Journal of the American Academy of Dermatology, Nov;67(5):945-54 (PubMed).

Lipof, J., Beck, L., Reddy, S., Southgate, R., Carney-Young, K. and Hammert, W. (2017) Necrotizing Sweet Syndrome of the Upper Extremity After Elective Hand Surgery. The Journal of Hand Surgery, Aug 19 (American Society for Surgery of the Hand).

Nakanishi, K. and Kinjo, M. (2016) Mimicker of necrotising fasciitis with systemic inflammatory response syndrome: recurrent necrotising Sweet’s syndrome associated with chronic myelogenous leukaemia. BMJ Case Reports, Mar 31 (PMC).

Otero, T., Barber, S., Yeh, D. and Quraishi, S. (2017) Necrotizing Soft Tissue Infection or Sweet Syndrome: Surgery Versus No Surgery? A Case Report. A&A Case Reports. Apr 1 (PMC).

Sanchez, I., Lowenstein, S., Johnson, K., Babik, J., Haag, C., Keller, J., Ortega-Loayza, A., Cohen, J., McCalmont, T., Demer, A., Mansh, M., Hylwa, S., Liu, J. and Shinkai, K. (2018) Clinical Features of Neutrophilic Dermatosis Variants Resembling Necrotizing Fasciitis. JAMA Dermatology, Oct 31 (PubMed).

2012-present, Sweet’s Syndrome UK



3 thoughts on “Necrotizing Sweet’s Syndrome

  1. My daughter was just diagnosed with sweet syndrome. She is 23 years old . They thought she had flesh eating in her arm. She had nine surgeries on her arm. Then attacked her left breast and then attacked her and left a Buttock. She had 15 surgeries of debridment in 7.5 months before someone figured out that she has sweet syndrome . We have been to hell and back since May 17, 2015 I would love to send her medical file to someone because she is a very unique case she was misdiagnosed by many centers here in Canada


  2. Hi Laura,

    I’m sorry to hear that your daughter has been so ill. Necrotizing SS can be a very nasty variant.

    If you would like others to learn about your daughter’s condition, the best thing that you can do is contact your daughter’s doctors and see if any of them are planning to/would consider writing a case-study detailing your daughter’s experiences.

    You could also try contacting the Canadian Organization for Rare Disorders (CORD) or the National Organization for Rare Disorders (NORD) to see if they can help. Rare Disease Day is approaching (Feb 29th 2016), and around this time, rare disease organizations are often looking for those who are willing to blog or share their experiences of having a rare disease.

    1. CORD:

    2. NORD:

    If you would like to share your experiences with those with Sweet’s syndrome or their families, you can also join our groups.

    1. Sweet’s Syndrome UK Facebook Group. This is a closed group, so you have to send a request to join. Also, you do not have to be from the UK to join. Link:

    2. Sweet’s Syndrome UK HealthUnlocked. You don’t have to be from the UK to join. Link:

    Take care,



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