Subacute Thyroiditis Diagnosed by Targeted Anterior Neck Examination

Subacute thyroiditis is a benign, self-limited inflammatory disorder of the thyroid that typically resolves spontaneously and was first described by de Quervain in 1904 [1]. Its prevalence is approximately 4.9 cases per 100,000 person-years [2]. Patients usually present with thyrotoxicosis (e.g., fever, tachycardia, and/or palpitations) accompanied by painful thyroid swelling. Although symptoms often abate over weeks to months, early manifestations can mimic acute pharyngitis, and a lack of improvement may result in unnecessary antibiotic prescribing [3]. Therefore, primary care physicians should maintain a high index of suspicion and perform a focused anterior neck examination to facilitate early diagnosis and support antimicrobial stewardship. We report a case in which a focused anterior neck examination was decisive. A 52-year-old woman with no relevant medical history and no regular medications was referred with a 1-week history of fever, sore throat, and fatigue. She denied sick contacts, recent vaccination, prior similar episodes, and reported no signs of a preceding infection. She had completed a 5-day course of oral levofloxacin without symptomatic improvement. On examination, her vital signs were as follows: blood pressure, 116/76 mmHg; heart rate, 88 beats per min; body temperature, 37.0°C; respiratory rate, 16 breaths per min; and oxygen saturation, 100% on room air. She was alert and in no distress. The oropharynx showed no marked erythema or tonsillar hypertrophy, and there was no cervical lymphadenopathy or lymph node tenderness. Focused questioning elicited no odynophagia or dysphagia; instead, she localized her discomfort to the anterior neck. A targeted neck examination revealed marked tenderness precisely over the thyroid gland, reproducing her typical pain (Video S1). Laboratory tests supported mild thyrotoxicosis and inflammation: free T4, 2.51 ng/dL; free T3, 5.86 pg/mL; thyroid-stimulating hormone (TSH), < 0.001 μIU/mL; thyroglobulin, 328.50 ng/mL; erythrocyte sedimentation rate, 71 mm/h; and C-reactive protein, 7.91 mg/dL. Thyroid autoantibodies were negative, including TSH receptor antibody, thyroid-stimulating antibody, anti-thyroid peroxidase antibody, and anti-thyroglobulin antibody. Thyroid ultrasonography demonstrated ill-defined hypoechoic areas with diffusely decreased intrathyroidal vascularity involving the entire left lobe (Figure 1) and the inferior portion of the right lobe, findings characteristic of subacute thyroiditis [3]. Based on the clinical, laboratory, and imaging data, subacute thyroiditis was diagnosed. She was treated with a nonsteroidal anti-inflammatory drug (loxoprofen 180 mg/day) for 1 month, with prompt symptomatic improvement; thyroid hormone levels normalized within 3 months of onset, after a transient hypothyroid phase at 1 month (fT4 0.70 ng/dL). This case underscores two practical points. First, subacute thyroiditis frequently masquerades as an upper respiratory tract infection early in the course, and more than 70% of patients reportedly require evaluation by two or more physicians before the correct diagnosis is made [3, 4]. Second, although the differential diagnosis is broad, neck pain is highly prevalent in subacute thyroiditis, with a reported frequency of up to 96.4% in a Japanese case series [5]. Neck pain is often the single most informative clinical finding. Some patients show the “creeping” phenomenon (pain migrating from one lobe to the other), likely reflecting patchy, evolving granulomatous inflammation. However, in Japanese clinical encounters, the phrase “nodo no itami” (“sore throat”) may denote oropharyngeal pain or anterior neck pain at the level of the pharynx. In our case, explicitly separating pain “on swallowing” from pain “at rest in the anterior neck” helped avoid misclassification as pharyngitis. The accompanying video highlights the assessment of pain on swallowing and focal thyroid tenderness—cues that aid recognition of subacute thyroiditis. Pain not exacerbated by swallowing, together with focal thyroid tenderness, localizes symptoms to the thyroid rather than the pharyngeal mucosa, lymph nodes, or strap muscles. Incorporating focused palpation of the thyroid into the evaluation of patients with prolonged common cold–like symptoms, persistent sore throat, or anterior neck discomfort can expedite diagnosis and help avoid unnecessary antibiotics. Ryuichi Minoda Sada: conceptualization, writing – original draft, writing – review and editing. Saki Sada Minoda: writing – review and editing, visualization. This work was conducted as part of “The Nippon Foundation—The University of Osaka Project for Infectious Disease Prevention”. We would like to thank Editage (www.editage.jp) for English language editing. We appreciate the educational insights provided by the Department of Geriatric and General Medicine, Graduate School of Medicine, The University of Osaka, at its clinical conference. The authors have nothing to report. Informed consent was obtained from the patient for publication of this case report, including any accompanying images and videos. The patient's anonymity has been preserved. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request. Video S1: Detailed history-taking and targeted physical examination for neck symptoms. 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