A previously healthy 13-year-old girl presents to the emergency department with a 2-week history of worsening sore throat and a 4-day history of left neck swelling, pain, and fever. Results of evaluation by a prior clinician at the onset of symptoms included a negative rapid streptococcal antigen test and a positive heterophile antibody test, prompting treatment with oral corticosteroids for 5 days as an anti-inflammatory medication. The girl now reports pain with swallowing, decreased oral intake, and left-sided head tilt for the past 24 hours.
On physical examination, the girl has a temperature of 38.4°C and appears to be in no acute distress. In addition, her heart rate is 91 beats/min, respiratory rate is 20 breaths/min, and blood pressure is 119/69 mm Hg. She has a warm, very tender, firm, anterior, left-sided 1.5-cm mass at the level of the thyroid gland. The mass moves when she swallows. Findings on the rest of her physical examination are normal.
Laboratory investigation reveals a white blood cell count of 17.2×103/μL (17.2×109/L) with 74% neutrophils and 14% lymphocytes, hemoglobin of 13 g/dL (130 g/L), and platelet count of 423×103/μL (423×109/L). C-reactive protein (CRP) measurement is elevated at 1.6 mg/dL (normal, 0.3 to 1.0 mg/dL).
Images from a computed tomography (CT) scan of her neck with intravenous contrast enhancement are shown below.
What's the diagnosis?
***See first comment for answer.
The patient's physical and laboratory findings and CT scan of the neck are consistent with acute suppurative thyroiditis. The CT scan reveals a multilocular inflammatory phlegmon/abscess-in-evolution involving the superior pole of the left lobe of the thyroid gland.
ReplyDeleteAdditional studies reveal an elevated thyroid stimulating hormone (TSH) value of 10.1 mIU/mL (normal, 0.35 to 5.5 mIU/mL) with a normal free thyroxine concentration of 1.5 ng/dL (19.3 pmol/L) as well as negative results on thyroid globulin and peroxidase antibody testing.
The thyroid gland is a rare site of infection due to its complete encapsulation, large vascular supply, and high concentration of iodine. The pathogenesis of suppurative thyroiditis includes descending infection from oral flora through a congenital pyriform sinus fistula, hematogenous seeding, direct extension from an adjacent structure, and spread through a perforated esophagus.
Recurrent episodes of suppurative thyroiditis may occur in patients who are found to have a pyriform sinus fistula connecting the oropharynx to a persistent remnant of the fourth branchial pouch. Resection of the tract is necessary in this situation. Of note, the fistula most commonly drains to the left side of the gland, and children who have suppurative thyroiditis typically have had a preceding upper respiratory tract infection with subsequent bacterial infection descending to the thyroid gland through the pyriform sinus tract.
Reference & more discussion:
http://pedsinreview.aappublications.org/content/32/9/385.full?rss=1