Polymyalgia Rheumatica Evolved into RS3PE Syndrome. What is the Culprit: Idiopathic or Secondary, Following mRNA-Based COVID-19 Vaccines? A Case Report and Brief Review of the Literature

We describe the clinical case of a 74-year-old male patient who received the second Comirnaty/Pfizer anti-COVID-19 vaccine dose. After 3 weeks he showed the clinical signs of polymyalgia rheumatica. The history included mild chronic normocytic normochromic anemia and hypogammaglobulinemia, osteoarthritis disease, livedo reticularis, hypercholesterolemia, and arterial hypertension. Despite prolonged treatment with NSAIDs and dexamethasone, the disease evolved into remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome. Neoplastic diseases and associated collagen diseases were excluded. The clinical picture recurred, soon after, the booster dose of the Spikevax/Moderna vaccine. The inflammatory indices were high, the radiographs of the hands were free of erosions, the ultrasound investigations revealed bursitis of the shoulders, knee synovitis, marked subcutaneous edema of the lower limbs, hydrocele, bilateral Baker's cyst in the popliteal cavity, hematoma of a calf. The clinical picture, markedly improved, with oral prednisolone and was stabilized with the association of hydroxychloroquine. The finding of persistent hypomagnesemia was related to chronic intake of esomeprazole. The reports of rheumatological reactions in international databases and the rare cases of RS3PE syndrome following the COVID-19 vaccine described in the literature are considered.