SUN-306 - Recurrent Salmonella Thyroid Abscess with Destructive Thyrotoxicosis and Mediastinal Extension

Background
Acute suppurative thyroiditis (AST) is rare and often misdiagnosed due to overlapping features with subacute thyroiditis. Salmonella species are an exceptionally uncommon cause but carry an increased risk of recurrence and deep neck or mediastinal extension. Prompt recognition is critical to avoid delays in definitive management.

Clinical Presentation
A 41‑year‑old woman with prediabetes and class II obesity presented with acute anterior neck pain, swelling, dysphagia, fever, and tachycardia following a household outbreak of gastroenteritis. Notably, her children had recent exposure to reptiles. Thyroid ultrasound revealed a 4.7 × 3.4 × 2.2 cm hypoechoic right‑lobe lesion with punctate echogenic foci (TI‑RADS 5). Fine‑needle aspiration yielded purulent material, and cultures grew pan‑sensitive Salmonella species. Laboratory evaluation demonstrated thyrotoxicosis (TSH 0.02 µIU/mL, free T4 2.50 ng/dL) with elevated inflammatory markers. She was treated with intravenous ceftriaxone and beta‑blockade, then discharged on oral antibiotics.
Within one week, she was readmitted with worsening neck pain, odynophagia, and persistent thyrotoxicosis. Repeat ultrasound showed a 4.5 cm avascular cystic lesion. Antithyroid therapy was appropriately deferred given concern for destructive thyroiditis. A planned drainage was aborted due to minimal residual fluid, and she was discharged on oral ciprofloxacin.
She came back to Emergency Department a week later with recurrent fevers and tachycardia. Contrast‑enhanced CT of the neck demonstrated a recurrent 3.6 cm abscess with multiple satellite collections and inflammatory extension into adjacent soft tissues with concern for mediastinal involvement. Given clinical deterioration and progressive imaging findings, she underwent surgical incision and drainage with neck exploration and drain placement. No thyroid tissue resection was required.
Postoperatively, thyroid function followed a triphasic course consistent with destructive thyroiditis, including transient hypothyroidism followed by recovery. Thyroid autoantibodies were negative. At one‑year follow‑up, she remained clinically and biochemically euthyroid.

Conclusion
This case highlights the importance of distinguishing AST from subacute thyroiditis in patients with painful thyrotoxicosis. Salmonella-associated AST is exceedingly rare, with fewer than 30 cases reported in the literature, and carries increased risk of recurrence and deep tissue extension. Early imaging and timely surgical intervention are critical to prevent complications.

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