Today is SWEET'S SYNDROME UK DAY, and I thought it would be relevant to post about Sweet's syndrome (SS) developing secondary to COVID-19.
Infection, particularly upper respiratory tract and gastrointestinal, is a well documented trigger for SS.
[CASE-STUDY] COVID-19 presenting with atypical Sweet's syndrome.
A 61-year-old woman was admitted to hospital with a one week history of skin lesions on her face and fever. She was also experiencing fatigue, muscle aches and joint pain. There were more lesions on her scalp, extremities, trunk, and mouth ulcers (aphthous). Blood tests showed a raised white blood cell count, including neutrophil count (83%), and raised ESR and CRP, indicating increased levels of inflammation in the body. The first CORONAVIRUS (SARS-Cov-2) test from a nose and throat swab was negative, but CT scan of the chest showed lung involvement. The patient was given hydroxychloroquine, azithromycin and Tamiflu (not proven treatments for COVID-19). The results of a skin biopsy from the right elbow (diffuse neutrophilic infiltrate in upper dermis, but also some subcutaneous involvement) alongside the clinical findings were interpreted as an ERYTHEMA NODOSUM – LIKE SWEET’S SYNDROME (see notes).
A repeat SARS-Cov-2 test was positive. A second CT was given due to prolonged fever, showing a diffuse bilateral parenchymal lung infiltration above 30% (associated with infectious disease affecting the lungs, e.g. pneumonia). Intravenous TOCILIZUMAB, a biologic, was given once. This is a drug that works by blocking INTERLEUKIN 6 (IL-6), a protein and CYTOKINE that is part of the body’s inflammatory and immune processes. Too much IL-6 can cause inflammation and tissue damage (see notes). Favipiravir, an antiviral, was started for 5 days (not a proven treatment for COVID-19). Fever subsided within 24 hours, and the skin lesions resolved.
SS can be reactive, an immune reaction against drugs, tumours or microbial agents such as a virus. This may start a CYTOKINE CASCADE resulting in SS - an overproduction of immune cells and their activating compounds (cytokines). In this case, SARS-Cov-2 was the most likely SS trigger. The patient’s abnormal immune response to COVID-19 has been proposed to be centred around neutrophils, and neutrophils and NETs (neutrophil extracellular traps) have been seen in the lungs in COVID 19. NETs are mesh or web-like structures released by neutrophils to trap and eliminate microbes. Cells in oral aphthous ulcers are also predominately neutrophils.
Overlapping symptoms of SS with COVID 19 made diagnosis difficult. Skin lesions can be a symptom of COVID 19 (see notes).
Taşkın, B., Vural, S., Altuğ, E., Demirkesen, C., Kocatürk, E., Çelebi, İ., Ferhanoğlu, B. and Alper, S. (2020) COVID-19 presenting with atypical Sweet's syndrome. Journal of the European Academy of Dermatology and Venereology, May 26. doi: 10.1111/jdv.16662 (Wiley).
ADDITIONAL NOTES (see links for more info).
1. Erythema nodosum is a skin condition that causes inflammation of the subcutaneous fat – the fatty tissue under the dermal skin layer. It can look like SS, particularly a variant of SS called subcutaneous SS or Sweet’s panniculitis.
2. "A multicentre, randomised controlled trial of tocilizumab (IL-6 receptor blockade, licensed for cytokine release syndrome), has been approved in patients with COVID-19 pneumonia and elevated IL-6 in China (Mehta et al, 2020)."
3. IL-6 has been shown to play a role in SS.
4. Dermatological symptoms of COVID-19: an erythematous exanthem; livedo reticularis; cutaneous vasculitis; acute urticaria; chickenpox-like blisters; 'COVID toes', - like pernio/chilblains or frostbite.
- COVID‐19 Presenting with Atypical Sweet’s Syndrome onlinelibrary.wiley.com/doi...
- Mehta et al (2020) COVID-19: consider cytokine storm syndromes and immunosuppression. thelancet.com/journals/lanc...
- Cytokine release syndrome in severe COVID-19: interleukin-6 receptor antagonist tocilizumab may be the key to reduce mortality sciencedirect.com/science/a...
- Serum cytokine profile in pediatric Sweet’s syndrome: a case report ncbi.nlm.nih.gov/pmc/articl...
- Concurrence of Sweet's Syndrome, Pathergy Phenomenon and Erythema Nodosum-like Lesions ncbi.nlm.nih.gov/pmc/articl...
- COVID-19 and dermatology patients dermnetnz.org/topics/covid-19/