Background and Aims

Acute suppurative thyroiditis (AST) is uncommon because the exceptional anatomy of the thyroid gland makes it resistant to microbial colonization. It occurs more frequently in patients with anatomical deformities such as pyriform sinus fistula and in immunocompromised patients. Since this is an endocrine emergency that is potentially fatal, early diagnosis and prompt management are important. Here, we report a case of AST caused by methicillin-resistant Staphylococcus aureus (MRSA) in patient with type 1 diabetes, which is initially difficult to differentiate from subacute thyroiditis.

Methods

A 32-year-old woman with type 1 diabetes and untreated ocular myasthenia gravis reported right-sided neck swelling, dysphagia, and bilateral thigh pain. The patient was diagnosed with subacute thyroiditis and prescribed prednisolone and ibuprofen. Four days later, she presented to the emergency department reporting presyncope and worsening symptoms. The patient underwent a physical examination, laboratory analysis, computed tomography (CT), and ultrasonography (US).

Results

Physical examination revealed tachycardia (114 beats per minute) and mild right thyroid tenderness to palpation. In the laboratory analysis, the patient had elevated inflammatory parameters (WBC 16.0 × 10³/μL, ESR 94 mm/hr, CRP 34.23 mg/dL). Thyrotoxicosis (Thyroid stimulating hormone (TSH) 0.01 μIU/mL, free thyroxine (fT4) 5.13 ng/dL) had reported without TSH receptor antibodies. She had acute kidney injury (creatinine 1.28 mg/dL), and elevated CK-MB levels (3.61 μg/L). The patient initially had neither hyperglycemia (134 mgdL) nor acidosis despite a high hemoglobin A1c level (10.3%). However, follow-up blood pressure dropped to 74/44mmHg. Empirical antibiotic (ceftriaxone) and prednisolone treatment was started.

CT scan revealed hypodense masses with peripheral enhancement consistent with abscesses in the right thyroid gland, right axilla, chest wall, right kidney, and both thighs. The patient also had pulmonary septic embolism with pleural effusion on CT scan and pericarditis with pericardial effusion on echocardiography. For diagnostic and therapeutic purposes, US-guided aspiration of the thyroid abscess and percutaneous drainage of the pericardial effusion were performed. MRSA was isolated from thyroid pus, pericardial effusion, urine, and blood. Ceftriaxone was changed to vancomycin, a susceptible antibiotic.

After 5 days, no MRSA was identified in the blood. Two weeks later, she was prescribed levothyroxine due to converted into hypothyroidism (TSH 6.13 μIU/mL, fT4 0.44 ng/dL).

Conclusions

This case is a life-threatening disseminated MRSA infection affecting the thyroid gland and several other organs, and was initially difficult to distinguish it from subacute thyroiditis. Therefore, prompt diagnosis and treatment of AST is strongly required, especially in patients refractory to steroid treatment for subacute thyroiditis.