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Original Studies

Acute suppurative thyroiditis in children

CHI, HSIN MD; LEE, YANN-JINN MD; CHIU, NAN-CHANG MD; HUANG, FU-YUAN MD; HUANG, CHI-YU MD; LEE, KUO-SHENG MD; SHIH, SHIN-LIN MD; SHIH, BING-FU MD

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The Pediatric Infectious Disease Journal: May 2002 - Volume 21 - Issue 5 - p 384-387
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Abstract

INTRODUCTION

Acute suppurative thyroiditis (AST) is a rare disorder in children. 1 The thyroid gland is resistant to bacterial infection because of a rich blood and lymphatic supply, high iodide content and protective fibrous capsule. 2 In 1979 Takai et al. 3 reported 7 Japanese patients with AST resulting from a fistula originating in the left pyriform sinus. Congenital pyriform sinus fistula is an embryonic remnant of either the third or fourth pharyngeal pouch. 4, 5 AST is often related to remnants of the branchial pouches, including pyriform sinus fistula or thyroglossal duct remnant, especially in children. 6, 7 We report 15 Taiwanese children with AST during a 16-year period.

PATIENTS AND METHODS

Fifteen patients with AST were treated in our pediatric department during the 16 years from 1985 through 2000. The diagnostic criteria for AST consisted of a tender anterior neck mass with or without fever, mixed echogenicity with sonolucent area on thyroid echography, decreased uptake area in radionuclear scanning and confirmation of infection by needle aspiration. Esophagography was performed after the inflammation had subsided, usually 2 weeks after completion of antibiotic therapy. The patients were followed at our pediatric clinic and by telephone inquiry. Their clinical, laboratory and radiologic findings were retrospectively analyzed.

Bacteriology

Pus was obtained by echo-guided aspiration. It was inoculated on aerobic blood plate, kanamycin-vancomycin plate, anaerobic blood agar, chocolate agar, eosin methylene blue agar and phenylethyl alcohol agar. The anaerobic blood and kanamycin-vancomycin plates were incubated at 35°C in an anaerobic chamber for at least 48 h. The remaining plates were incubated at 35°C in a CO2 incubator overnight. If bacteria were isolated subsequent identification and susceptibility tests were performed. The antimicrobial susceptibility test was performed by Kirby-Bower disc diffusion method using the BBL Sensi-Disc antimicrobial susceptibility test discs (BD Biosciences, Cockeysville, MD) according to the manufacturer’s instructions and in accordance with the criteria of National Committee for Clinical Laboratory Standards.

Statistical analysis

Data were expressed in mean ± sd (ranges) and analyzed with Fisher’s exact test, the Mann-Whitney rank sum test and the goodness of fit test. For all analyses P values of <0.05 were considered statistically significant.

RESULTS

The patients’ demographic data are summarized in Table 1. There were 8 girls and 7 boys. Their age at diagnosis was 6.1 ± 2.9 years (1.5 to 9.8 years). The duration of follow-up was 7.9 ± 4.3 years (0.2 to 15.3 years). Thirteen (87%) had a thyroid mass on the left side, whereas only 2 had right thyroid involvement (P < 0.05). None had bilateral disease. Fever was detected in 12 cases (80%) (Table 2). Ten patients had peripheral white blood cell counts exceeding 10 × 109/mm3, and 8 had an elevated C-reactive protein value or erythrocyte sedimentation rate. Five patients (33%) reported an antecedent upper respiratory infection. Empiric antibiotics were used before culture in 7 patients (Table 3). Pathogenic organisms were identified on culture in 8 patients and were found on Gram-stained smear in another 2 patients. Mixed flora was grown in 50% of the positive cultures. Streptococcus spp. were the most common organisms (50%), including alpha-hemolytic Streptococcus (4 patients) and non-group A, B, D beta-hemolytic Streptococcus (2 patients). Others included Haemophilus influenzae nontypable (2 patients) , Staphylococcus aureus (1 patient), Enterobacter cloacae (1 patient), Eikenella corrodens (1 patient) and Fusobacterium russii (1 patient). The thyroid function tests including thyroid-stimulating hormone and thyroxine or free thyroxine were normal in all patients. Sonography was performed in all cases to localize the inflammatory area. Sonolucent foci beside the thyroid with or without involvement of the thyroid were found in all. Thyroid nuclear scan showed decreased uptake in the involved lobe in 92% (12 of 13). Computed tomography showed a perithyroidal hypodense area in all 3 of those examined. Esophagography was performed in all 15 patients; 5 had a pyriform sinus fistula (Fig. 1). During the follow-up period 7 patients had recurrent episodes (Table 1). In only 1 of these children was a pyriform sinus fistula detected. The duration of antibiotic therapy varied from 14 to 21 days depending on the patient’s clinical response. Penicillin (11 patients) was administered initially and then changed according to the results of the culture and susceptibility testing. Five patients required incision and drainage in addition to antibiotic therapy.

T1-7
Table 1:
Demographic data of children with acute suppurative thyroiditis
T2-7
Table 2:
Manifestations of acute suppurative thyroiditis
T3-7
Table 3:
Microorganisms isolated from children with acute suppurative thyroiditis and their susceptibility
F1-7
Fig. 1:
Esophagography showing a fistula (lower arrow) extending from the apex of the left pyriform sinus (upper arrow) downward to the perithyroidal area.

DISCUSSION

Pyriform sinus fistula is the most common underlying abnormality in AST. 2 Hematogenous or lymphatic spread has also been suggested as a route of infection. 6, 7 Takai et al. 3 first demonstrated that suppurative thyroiditis is often associated with a fistula track from the apex of the left pyriform sinus to the thyroid or perithyroidal space. Subsequently others have found pyriform sinus fistula as a source of AST, especially in recurrent cases. 5, 8 AST is often associated with an antecedent upper respiratory infection or otitis media. An infection of the upper respiratory tract may alter local immune defenses and prime the area for bacterial overgrowth of indigenous flora, which then spread by a communicating fistula to the perithyroidal space and then the thyroid gland itself. 4 The clinician must be aware of a possible fistula between the pyriform sinus and the perithyroidal space, especially in patients with recurrent episodes of acute suppurative thyroiditis. 9

Features of AST in children include fever, dysphagia, local erythema, skin warmth and tenderness. Stridor caused by tracheal compression by a mass effect has been noted in neonates. 10 Sudden onset of painful swelling in the thyroid region accompanied by high fever and sore throat are characteristic features. The left lobe was involved in most patients (87%), consistent with other reports. 2, 5 The left lobe predominance reflects the presence of a pyriform sinus fistula, which is predominantly observed on the left. Thyroid function test results are usually normal, 8, 10 as in our study.

Sonography is valuable for distinguishing solid vs. cystic or mixed lesions. Serial sonography may reveal an evolving abscess with a perithyroidal hypoechoic area. 11–13 Computed tomography is extremely useful in establishing the diagnosis early because it can evaluate the iodine content of the thyroid gland and provides more accurate mapping than ultrasound and nuclear medicine techniques. 14, 15 Thyroid radionuclear imaging is a useful diagnostic tool in AST, typically demonstrating an area of diminished or absent uptake limited in the involved lobe or pole. 7, 11, 16

Either computed tomography or esophagography can identify a pyriform sinus fistula. 3, 8 However, identification of a fistula may be difficult or impossible during acute inflammation because the tract is closed secondary to edema. Esophagography should be performed during the quiescent phase. 17 A pyriform sinus fistula was found in one-third of our patients and in only one of seven recurrent cases. This suggests that repeat esophagography is necessary in patients with recurrent infections.

AST is usually caused by oral flora including Streptococcus spp., Staphylococcus spp. and anaerobic bacteria. 11 Berger et al. 1 reported that three-fourths of the organisms from pus or thyroid tissue were Gram-positive cocci. Other reported organisms include Bacteroides, Peptococcus, Enterobacteriaceae, Eikenella and Haemophilus. Anaerobes often coexist with aerobes. Alpha- and beta-hemolytic Streptococcus and anaerobes account for 70% of cases, and mixed pathogens occur in >50% of cases in children. 1 However, anaerobe was isolated from only one patient in our study. This might be because of the absence of the anaerobic microorganisms or failure of anaerobic bacteria isolation. Clinical specimens containing anaerobes require special handling to enable satisfactory recovery of these pathogens. 18 Inadvertently exposing the bacteria to oxygen during specimen collection, transportation and culture setup may make the anaerobes unrecoverable. Some anaerobes are susceptible to empiric antibiotics such as penicillin and clindamycin. The use of such antibiotics in our patients may also have decreased the isolation rate of anaerobes. Confirmation of the etiologic agent by culture is important to ensure correct choice of antibiotics.

Treatment should consist of broad spectrum antibiotics and adequate incision and drainage of the abscess because of the possibility of mixed polymicrobial infections. 19 Penicillin or clindamycin would provide good coverage except for H. influenzae and other Gram-negative organisms for which second or third generation cephalosporin may be combined for coverage. 20 If a fistula is present, complete removal of the epithelial tract is essential to prevent recurrence. 21 Miyauchi et al. 2 reported that 25 patients with complete fistulectomy had no recurrence, whereas 6 of 16 patients without fistulectomy had recurrences. None of the 5 patients in our series who had a pyriform sinus fistula underwent fistulectomy. One had a recurrence during the follow-up period.

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Keywords:

Acute suppurative thyroiditis; pyriform sinus fistula; children

© 2002 Lippincott Williams & Wilkins, Inc.