RESUMEN
RATIONALE: The occurrence of subacute thyroiditis (SAT) after vaccines or after hyaluronic acid skin fillers is very rare and might be related to genetic susceptibility. We suggest that the co-administration of both products could potentially increase the possibility of development of SAT. PATIENT CONCERNS: A 58-year-old Caucasian healthy female initially presented with chills, myalgia, dysphagia, sore throat, dry cough, fatigue, and intermittent fever of 38.5°C orally after simultaneous injection of an influenza vaccine and a dermal filler containing hyaluronic acid. Ten days later the patient developed palpitations and neck pain radiating to the left jaw. DIAGNOSIS AND INTERVENTIONS: She was diagnosed with SAT on day 16 after her first visit and responded promptly to etoricoxib treatment. OUTCOMES: The patient progressed clinically from hyperthyroidism to euthyroid state and eventually to hypothyroidism and further testing showed she had HLA B-35 haplotype. LESSONS: Physicians should be aware that SAT might be associated with the administration an influenza vaccine and this possible association might increase if the vaccine was co-administered with a dermal filler.