A Case of Fasciitis Following SARS-CoV-2 mRNA Vaccination: Case Review and Literature Overview.

Vaccines play a crucial role in preventing various infectious diseases, and their safety has been well established, with adverse effects generally being mild and transient. However, in rare instances, serious adverse events, including autoimmune diseases, have been reported following vaccination. Among these conditions, fasciitis is extremely rare. To our knowledge, the present report describes the first documented case of fasciitis occurring in combination with erythema nodosum after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A 29-year-old Japanese woman presented with bilateral lower leg swelling, myalgia, ankle arthralgia, and transient painful erythema 15 days after vaccination. The erythema was diagnosed as erythema nodosum by skin biopsy and resolved spontaneously. Physical examination revealed swelling and tenderness of the gastrocnemius muscle, without skin sclerosis. Eosinophilia was not observed. Magnetic resonance imaging (MRI) demonstrated high signal intensity in the fascia and gastrocnemius muscles bilaterally. Creatine kinase levels and electromyography findings were normal, and myositis-specific autoantibody tests were negative. The patient was treated with 15 mg/day prednisolone, which led to symptomatic improvement. After discontinuation of glucocorticoids, swelling and tenderness of the gastrocnemius muscle worsened; however, the abnormal MRI findings subsequently resolved, and glucocorticoids were ultimately discontinued. Our review of previously reported cases of fasciitis following SARS-CoV-2 vaccination indicated favourable treatment responses in all patients, regardless of treatment with glucocorticoid monotherapy, combination immunosuppressive therapy, or no treatment. Although rare, clinicians should be aware of the possibility of post-vaccination fasciitis.