Thyroid Abscess with Esophageal Perforation in Papillary Thyroid Cancer

Dear Editor:

Thyroid abscesses are rare. Their timely diagnosis requires a high index of suspicion. Thyroid abscess may originate from either hematogenous or lymphatic spread but the most common route is a congenital pyriform sinus fistula. Other predisposing factors include foreign body ingestion or an anatomically altered thyroid gland, as may occur in goiters or thyroid cancer (1). Here we present a 55-year-old man with papillary thyroid carcinoma (PTC) and a thyroid abscess that appeared to cause esophageal perforation. This does not appear to have been reported before.

A 55-year-old man presented to our department with left-sided lower neck pain lasting over 1 month. The medical history was unremarkable except for a recent upper respiratory infection (URI). Despite treatment with systemic antibiotics at the referring hospital, neck pain and tenderness worsened. At presentation, the patient was afebrile and the neck examination revealed a tender lesion on the left side at the level of the thyroid gland. On flexible laryngoscopic examination, the mucosa of the pharynx and both pyriform sinuses appeared to be normal. Laboratory studies revealed elevation of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), but the white blood cell count was in the normal range.

The serum total triiodothyronine was 146 ng/dL, free thyroxine was 6.97 ng/dL, and thyroid-stimulating hormone was <0.005 μIU/mL. The computed tomography (CT) scan from the referring hospital revealed an ill-defined hypodense lesion in the left thyroid lobe with gas within the gland and a hypodense nodule in the right thyroid lobe, as well as a calcified lesion in the left thyroid lobe, suggesting malignancy (see Supplementary Data, available online at www.liebertonline.com/thy). The pharyngoesophagogram showed an esophageal fistula at the cervical level without pyriform sinus fistula (See Supplementary Data). Ultrasound examination of the neck demonstrated an abscess in the left thyroid lobe and nodules with malignant characteristics in both thyroid lobes (an 8-mm-sized markedly hypoechoic nodule with speculated margin in the right lobe and a 5-mm-sized densely calcified lesion in the inferolateral portion of the abscess). Based on these observations, the patient was tentatively diagnosed with deep neck abscess associated with intrathyroidal abscess of the left lobe, esophageal fistula, and probable multifocal PTC in both lobes. The abscess was surgically evacuated and bacterial culture was done. A total thyroidectomy was performed, including removal of adjacent necrotic tissue, and an esophageal fistula at the trachea-esophageal groove was repaired. Culture of the abscess contents grew Klebsiella pneumoniae and histological examination of the specimen revealed intrathyroidal abscess and PTC in both lobes without extra-thyroid spread.

Thyroid abscess can have a variety of causes, including pyriform sinus fistula, but the route of infection is not always clear. Serotype K1 K. pneumoniae has a propensity to form abscesses in distant sites, and we speculate that K. pneumoniae infection secondary to preceding URI may have spread hematogenously to the patient's anatomically altered thyroid gland. Notably, the esophagus has been thought to be relatively resistant to invasion by malignancy or infection from the thyroid. Intraoperatively, the thyroid mass was found to be separated from the esophagus by an abscess and a histopathological review of our surgical specimen did not show cancer invasion into the esophagus. Therefore, we think that esophageal perforation resulting from direct invasion can be excluded.

Infectious necrotizing esophagitis is a rare entity characterized by mucosal necrosis and, rarely, perforation. Causative organisms include bacteria, such as K. pneumoniae and Mycobacterium tuberculosis; fungi; and viruses (2). Recently, Liu et al. reported a case of K. pneumoniae infection in the deep neck with acute necrotizing esophagitis resulting in esophageal perforation (3). As a possible mechanism of esophageal perforation in our case, we suggest that both K. pneumoniae thyroid abscess by hematogenous spread from the upper respiratory tract and invasive necrotizing infection to the esophagus might have lead to perforation (See Supplementary Data).

The symptoms of thyroid abscess are swelling in the anterior neck at the thyroid gland level, pain, hoarseness, fever, and dysphagia. Symptoms may be preceded by acute URI (4). Common abnormal laboratory findings show leukocytosis and elevated ESR and CRP. Thyroid function is generally normal, but both thyrotoxicosis and hypothyroidism are occasionally seen. Radiological investigations for suspected thyroid abscess include a plain X-ray of the neck and chest, and ultrasonographic examination and CT scan of the neck. A pharyngoesophagogram should be performed for exclusion of the pyriform sinus fistula.

If the thyroid abscess is not managed quickly several complications, including septicemia, retropharyngeal abscess, tracheal or esophageal rupture, internal jugular vein thrombosis, vocal cord palsy, and mediastinitis, may occur. Treatment of thyroid abscess includes incision and drainage, combined with culture and appropriate antibiotic therapy, and, occasionally, thyroidectomy.