Radiation recall dermatitis triggered by inactivated COVID-19 vaccine.

Dear Editor,

Radiation recall dermatitis (RRD) is an acute inflammatory reaction that is localized to an area of skin previously exposed to radiation and is known to be triggered by various systemic drugs. It can be observed weeks to years after cessation of radiotherapy, and the time interval between administration of the reaction‐triggering drug to the onset of lesions varies from minutes to days. RRD is characterized by erythema, oedema, urticaria‐like lesions, desquamation, vesiculation and, in severe cases, necrosis and ulceration. RRD is mainly triggered by cytotoxic chemotherapeutics, but there are also several reports with antibiotics, monoclonal antibodies and immunomodulators.– We report a patient with melanoma who developed RRD following the first dose of COVID‐19 vaccine.

A 60‐year‐old woman with a history of melanoma presented with a sudden‐onset painful lesion on the medial side of her right leg. The patient’s medical history revealed that she had received hypofractionated radiotherapy of 30 Gy over 10 days to four separate regions on her right leg 2 years and 3 months previously. She was still on the dabrafenib/trametinib combination therapy that had been started just over 2 years before her presentation.

Physical examination revealed a well‐demarcated, erythematous, indurated plaque confined to an area of previous irradiation (Fig. 1). There were no active lesions on other irradiated parts of her right leg. The patient reported no trauma or application of any topical agent in the area where the existing erythematous lesion was located. She also had not started any new systemic medication, but she had received her first dose of a COVID‐19 vaccine, the inactivated CoronaVac vaccine (Sinovac, Beijing, China), 5 days before the onset of erythema.

Figure 1

(a) Right leg with areas of previous irradiation, showing postinflammatory hyperpigmentation on the knee and recently developed erythema on the medial aspect of the lower part; (b) closer view of the well‐demarcated, erythematous, indurated plaque.

Histological 5‐mm punch biopsy taken from the erythematous plaque showed epidermal intercellular oedema, lymphocyte exocytosis and rare necrotic keratinocytes as well as increased dermal collagenization and fibrosis (Fig. 2). Based on these findings, our patient was diagnosed with RRD triggered by COVID‐19 vaccine.

Figure 2

(a) Increased dermal collagenization and fibrosis, secondary to previous radiotherapy; (b,c) epidermal intercellular oedema, lymphocyte exocytosis and rare necrotic keratinocytes (arrow). Haematoxylin and eosin, original magnification (a) × 40; (b,c) × 200.

A wide range of cutaneous manifestations of SARS‐CoV‐2 infection have been described to date; however, data concerning COVID‐19 vaccine‐associated cutaneous findings have only started to emerge recently. The reported cutaneous manifestations after Pfizer‐BioNTech COVID‐19 vaccine include erythematous plaques at the injection site, diffuse morbilliform rash, mild erythema at various body sites and positive dermographism. Recently, Soyfer et al. described two patients with RRD following two doses of the Pfizer‐BioNTech vaccine. The exact mechanism of RRD is unknown and a possible explanation is a local hypersensitivity reaction triggered by the vaccine via upregulation of inflammatory cytokines that were already increased in the area of irradiation., To our knowledge, this is the first case of RRD triggered by the CoronaVac vaccine. As SARS‐CoV‐2 vaccines are continuing to be administrated on a large scale, clinicians should be aware of the potential risk of RRD in patients with a previous history of radiotherapy.

Acknowledgement

The patient provided written informed consent to publication of the case details and photographs.