The initial symptoms of PSF include neck mass with or without abscess, acute thyroiditis, and thyroid lesion [1–3]. In some cases, particularly in neonates, a neck mass compressing the surrounding structure, resulting in dyspnea, has been reported [2, 4]. However, hoarseness, as the first symptom of PSF, has not yet been reported. This study presents a case of PSF with hoarseness as the first symptom preceding fever and neck swelling. Pharyngoscopy revealed swelling of the arytenoid region, with purulent retention. The left vocal cord was swollen but not paralyzed. Hoarseness disappeared with DEX on the day after admission, and swelling disappeared on the third day. Thus, hoarseness may be derived from the swelling of the left vocal cord due to the PSF infection. As vocal cord movement was normal, the hoarseness was not caused by a recurrent laryngeal nerve palsy. Dyspnea has been reported to be secondary to lesion compression in some patients with PSF. However, in our case, no evidence of airway obstruction was identified, although hoarseness, fever, and anterior neck swelling were noted. Hence, the larynx and airways in patients with hoarseness need to be evaluated.
Acute suppurative thyroiditis is a rare clinical condition in childhood because the thyroid gland is remarkably resistant to infections owing to its high iodine content, rich blood and lymphocyte supply, and protective fibrous capsule [5]. Infection with PSF is often reported to cause acute suppurative thyroiditis [1, 6]. In our case, a low TSH level and high FT4 and TG levels suggested that the abscess had partially destroyed the thyroid gland. Considering the suppressed TSH level, high FT3 level may have occurred before admission, although the FT3 level on admission was low. The presence of complicated low T3 syndrome due to infection and decreased intake was indicated. A previous study has reported that low T3 syndrome was associated with acute suppurative thyroiditis because of PSF infection in an adult case [7]. The thyroid hormone levels returned to the normal range within 3 weeks.
Diagnosing PSF can be difficult owing to its rarity, and PSF should be considered when examining neck abscesses or acute suppurative thyroiditis. In the acute phase of infection, identifying the fistula tract is difficult because of swelling of the mucosa and surrounding tissues [6]. In our case, acute-phase contrast-enhanced CT revealed an abscess partially infiltrating the thyroid gland and an air pocket near the pyriform sinus. The air pocket resembled a ductal structure from the pyriform sinus to the thyroid, which was elevated by the abscess, thus suggesting the presence of a PSF. After treatment of the acute inflammation, we confirmed the result with barium esophagogram, confirming the diagnosis of a PSF.
Antibiotics and percutaneous drainage are commonly used to treat PSFs in the acute phase of infection [2]. In our case, the patient was treated with corticosteroids to improve the laryngeal swelling. Surgical fistula removal is necessary for treating PSFs [2]. Obliteration of the inner orifice by chemocauterization, laser coagulation, and biocauterization is also effective in the management of PSFs [8]. However, a PSF may not be entirely closed through these methods. Therefore, complete fistula resection is a reasonable treatment method for recurrent cases. In the present case, although we recommended chemocauterization because it was the first episode, the patient’s family did not select this method, and the patient is currently under observation.
This study describes a rare case of PSF with acute suppurative thyroiditis with hoarseness arising as the first symptom. Therefore, the possibility of PSF in patients presenting with hoarseness as their first symptom should be considered.