Unilateral pharyngalgia as the dominant symptom in subacute thyroiditis: Case series and analysis of diagnostic pitfalls in clinical practice

Abstract

Subacute thyroiditis is a condition with varied and often misleading symptoms, which can lead to diagnostic delays and inappropriate treatment. This case series focuses on 32 patients who presented with unilateral pharyngalgia as the primary symptom and were ultimately diagnosed with subacute thyroiditis. The patients, aged 28–52 years with a female predominance (23 females and nine males), reported pharyngeal pain that lasted from 7 days to 3 months, with 19 having left-sided and 13 having right-sided initial pain. Of these patients, 43.7% (14/32) were initially misdiagnosed, primarily as pharyngitis or tonsillitis. Key diagnostic findings included thyroid tenderness, abnormal thyroid function, elevated erythrocyte sedimentation rate, characteristic manifestations on thyroid ultrasound, and decreased radioactive iodine uptake. Treatment varied by pain severity. In conclusion, unilateral pharyngalgia is frequently mistaken as other common throat conditions. Thyroid palpation should be routine in patients with unilateral pharyngalgia; positive findings warrant further tests (C-reactive protein, ultrasound, radioactive iodine uptake) to confirm subacute thyroiditis.

Clinically, subacute thyroiditis (SAT) presents as neck pain, often accompanied by otalgia and various systemic symptoms. ¹ The symptoms of SAT are diverse and misleading. Patients may be referred to emergency medicine, family practice, otolaryngology, or internal medicine departments, leading to delayed diagnosis and inappropriate use of antibiotics.^2–4 Most patients with a pharyngalgia first consult the otolaryngology department. However, these doctors tend to focus more on the oral cavity, pharynx, and larynx rather than the thyroid gland, which may result in missed diagnosis of SAT.

In recent years, our department has emphasized palpation of the thyroid gland in patients with pharyngalgia, especially those with unilateral pharyngalgia as the initial symptom, and diagnosed 32 cases of SAT. This is reported as follows. The reporting of this study conforms to the Case Report (CARE) guidelines. ⁵

Clinical information

Between January 2020 and December 2023, 32 patients with unilateral pharyngalgia as the primary complaint were ultimately diagnosed with SAT. All patients were from the Bethune International Peace Hospital. Using the electronic data systems, the following data were obtained for all patients. Information was collected with the patients’ informed consent. The patients were aged between 28 and 52 years, with 9 males and 23 females. Thyroid tenderness was graded on a visual analog scale as mild pain (1–3 points), moderate pain (4–6 points), and severe pain (7–10 points). Among them, 5 patients had severe pain, 21 had moderate pain, and 6 patients had mild pain.

At the time of presentation, patients complained of pharyngeal pain from 7 days to 3 months. The first symptom was pharyngeal pain, which started as unilateral pharyngeal pain on the left side in 19 patients and on the right side in 13 patients. Overall, 18 patients were diagnosed with SAT at the initial visit, and 14 were misdiagnosed. Four patients were misdiagnosed as acute pharyngitis, two as acute peritonsillitis, seven as chronic pharyngitis, and one as pericoronitis of the wisdom teeth. In the misdiagnosed patients, the thyroid area had not been palpated during the previous visit. All patients were carefully questioned about their symptoms and then underwent routine otolaryngological examinations, including oral cavity, hypopharyngeal and laryngeal examinations, and simultaneous palpation of the neck, especially the thyroid area.

Thyroid function tests and thyroid ultrasonography were performed, and erythrocyte sedimentation rate (ESR) and radioactive iodine uptake(RAIU) rate were measured in all 32 patients. Free T3 and/or T4 levels were elevated in 20 patients (62.5%) and normal in 12 patients (37.5%). ESR was >40 mm/h in 23 patients (71.8%). Ultrasound examination of the thyroid gland showed that 26 patients had unilobar lesions and 6 had bilobar lesions, and the ultrasound findings were consistent with SAT. RAIU measurements revealed low iodine uptake. The diagnosis of SAT was made based on clinical presentation, physical examination, laboratory test results, and ultrasonographic findings in accordance with the 2016 American Thyroid Association guidelines. ⁶ The diagnosis was established based on the presence of painful, tender, and hard goiter; elevation of ESR or C-reactive protein (CRP) levels; elevation of free T4 levels; suppression of serum thyroid-stimulating hormone levels; the presence of hypoechoic areas with blurred margins; and the appearance of decreased vascularization on ultrasonography of the painful thyroid regions.

Treatment was as follows. Six patients with mild pharyngalgia were administered nonsteroidal anti-inflammatory drugs. In addition, 21 patients with moderate pain were administered a starting dose of 0.3 mg/kg/d prednisone acetate. Five patients with severe pain were given a starting dose of 0.5 mg/kg/d prednisone acetate, with a weekly dose decreasing to 5 mg after remission. The course of treatment for all patients was 6–12 weeks.

Discussion

Clinically, owing to the nonspecific symptoms of SAT, correct diagnosis is often delayed for months.^3,4,7 SAT can be confused with common pharyngalgia and rare bacterial thyroiditis, leading to delayed diagnosis. ⁴ SAT usually starts in one lobe of the thyroid gland, and it may involve the opposite side, ⁸ just as the pharyngalgia that starts unilaterally and then extends to the whole pharynx. Unilateral pharyngalgia is a dominant symptom of SAT.

For years, neck pain was considered the main and most characteristic symptom of SAT. ⁹ When conducting a survey of the symptoms of 38 patients diagnosed with SAT, 28 (74%) presented with a sore or swollen throat. ⁴ If the initial complaint is pain in the throat, doctors often neglect to conduct an examination of the thyroid region. ¹⁰ The otolaryngologists did not palpate the thyroid region of patients with pharyngalgia, which resulted in a misdiagnosis rate of 43.7% (14/32) in this group. Kjellerup et al. ¹¹ reported that swallowing pain was present in 12/44 (27.3%) of patients diagnosed with SAT. Thyroid pain and/or tenderness are the main diagnostic criteria for SAT ¹¹ ; thus, thyroid palpation must be performed in patients with fever, neck pain, ear pain, and throat pain. ³ Pharyngalgia is usually a symptom of pharyngitis. Many conditions other than pharyngitis may lead to the complaint of pharyngalgia, ranging from localized to systemic disorders, including those with both infectious and noninfectious etiologies, and one of the localized disorders that may cause pharyngalgia is SAT. ¹² Unilateral pharyngalgia is commonly associated with common peritonsillitis, peritonsillar abscesses, stylohyoid syndrome, and advanced tumors of the pharynx. When confronted with a complaint of pharyngalgia, especially unilateral pharyngalgia, the attending physician must have the awareness to perform a thyroid palpation. If there is thyroid tenderness and hardening on palpation, further examination is necessary to determine if the diagnosis is SAT.

Thyroid tenderness and hardening on palpation are the most valuable pieces of information. Thyroid tenderness is present in almost 100% of SAT cases ¹³ due to the pressure on the thyroid capsule. The diagnosis of SAT is a combination of clinical manifestations, physical examination, laboratory tests, and thyroid ultrasonography.^7,11,13 Thus, in clinical practice, patients with pharyngalgia are routinely palpated for the thyroid gland, and patients with positive palpation are easily screened for SAT by performing relevant laboratory tests. Ultrasound evaluation plays an important role in the diagnosis and differential diagnosis of SAT. ¹⁴ The ultrasound manifestations of SAT are well established and typical. These manifestations often present as heterogeneous, diffusely or focally marked hypoechoic areas, such as “lava flow.” ¹⁵ Radioiodine uptake or thyroid isotope scans are not mandatory criteria for SAT diagnosis. ⁴ Both thyroid scintigraphy and RAIU testing are used to differentiate productive thyrotoxicosis (i.e. hyperthyroidism) from destructive thyrotoxicosis (i.e. acute thyroiditis and SAT), and decreased uptake is typically observed in the early phases of destructive thyroiditis. ¹⁶

This article emphasizes the significance of thyroid palpation in diagnosing SAT in patients with pharyngalgia. There were some limitations to the study. First, this research focused on the significance of thyroid palpation in screening SAT in patients with pharyngalgia. However, we did not record all patients with pharyngalgia; hence, we cannot determine the proportion of patients with SAT among all patients with pharyngalgia. Second, this is only a retrospective cross-sectional case series. The patients diagnosed with SAT did not undergo serial monitoring of thyroid function, ESR, and CRP level as well as other laboratory tests.

Conclusion

Thyroid palpation is recommended as a routine test in patients with unilateral pharyngalgia. Positive palpation of the thyroid region should be further evaluated by measuring CRP level, performing ultrasonography, and measuring RAIU rate to improve the chances of confirming the diagnosis of SAT. Moreover, SAT should be included in the otolaryngology residency training curriculum to increase physicians’ awareness of the disease.