Pyoderma gangrenosum after mRNA-based SARS-CoV-2 vaccine.

Dear Editor,

We describe the case of a 49‐year‐old man with a background of ulcerative colitis and an inoperable astrocytoma treated with a fourth‐line chemotherapy by bevacizumab and lomustine. Twenty‐two days after receiving the second dose of the SARS‐CoV‐2 Pfizer‐BioNTech mRNA‐vaccine Comirnaty®, he presented at the injection site a painful oedematous lesion rapidly progressing into a large necrotic ulcer with an erythematous border (Fig. 1). He had associated fever, headaches and asthenia. First, he was treated as an infectious abscess with antibiotics and surgical debridement, but the ulcer continued to worsen. We rectified the diagnosis for pyoderma gangrenosum (PG), which was successfully treated within 1 month with topical and systemic corticosteroid therapy (prednisone 1 mg/kg/d), as presented in Figure 2. Considering the good response to immunosuppressive treatment and prespecified 4 minor criteria (pathergy, papule then ulceration, peripheral erythema, inflammatory bowel disease [IBD]), diagnosis of PG was eventually retained. Even if biopsy is considered as a major criterion for PG diagnosis, it was not performed to avoid the risk of further pathergy. It has to be noted that his first shot of the same vaccine was well tolerated.

Figure 1

Dermatological aspect of pyoderma gangrenosum, located on the upper arm, 22 days after the second shot of the SARS‐CoV‐2 Pfizer‐BioNTech mRNA vaccine.

Figure 2

Evolution of pyoderma gangrenosum after being treated with topical corticosteroids and systemic steroid therapy (prednisone 1 mg/kg/day).

Delayed local skin reactions, are a rare side‐effect that usually present as a localized, transient, erythematous and oedematous plaque several days after the first or the second dose of the mRNA‐based SARS‐CoV‐2 vaccines named ‘COVID ARM’. They do not constitute a contraindication to a second injection. IBD is a well‐known risk factor for neutrophilic dermatosis as PG, and our patient had a history of ulcerative colitis. It has to be noted that, 2 days before PG occurrence, our patient was also treated with subcutaneous granulocyte colony‐stimulating factor (G‐CSF) injection in the thigh in order to prevent chemotherapy‐induced neutropenia. Cases of PG occurring after G‐CSF have been reported in the literature. Few cases of neutrophilic dermatosis such as Sweet syndrome have been reported with SARS‐CoV‐2 vaccines. , , , , In the World Health Organization global database of individual case safety reports ‘VigiBase’, after more than 11.6 billion doses of SARS‐CoV‐2 vaccines, 21 cases of PG have been reported with vaccines against SARS‐CoV‐2 (11 with the Comirnaty®‐Pfizer‐BioNTech‐ vaccine, 4 with the Spikevax®‐Moderna‐ vaccine, 4 with the Vaxzevria®‐AstraZeneca‐ vaccine and 2 with the COVID‐19 Janssen‐ vaccine). To our knowledge, only one case of PG has been published in a 27‐year‐old patient 24 h after receiving the first dose of Comirnaty® vaccine. In the ‘VigiBase’, PG has also been reported with various vaccines mainly smallpox, pneumococcal, herpes zoster, seasonal influenza and hepatitis A vaccines. In our case, the link between mRNA‐based SARS‐CoV‐2 vaccine and PG is suggested mainly by the PG location at the site of vaccine injection and the delay between the administration and PG occurrence. We hypothesize for our patient that the vigorous immune reaction induced by the SARS‐CoV‐2 vaccine triggered a pathergy phenomenon in a patient with medical (ulcerative colitis) and treatment (G‐CSF) conditions favouring neutrophilic dermatosis.

In conclusion, the occurrence of PG at the site of SARS‐CoV‐2 vaccine injection is a rare but potential condition that clinicians should consider.

Funding sources

None.

Conflicts of interest

None declared.