Thyroid abscess with transient hyperthyroidism in an adolescent girl –A case report

INTRODUCTION

Thyroid infections are rare at any age due to the protective anatomical and physiological characteristics of the thyroid gland, including rich vascular supply and lymphatic drainage, high iodine content, and a fibrous capsule.^[1] Acute suppurative thyroiditis (AST) is even less frequent and may progress to thyroid abscess, representing <0.7% of surgical thyroid conditions.^[2-4] In pediatric patients, thyroid abscesses are most often linked to congenital anomalies such as pyriform sinus fistula or malformations of the third or fourth branchial arches.^[5] Thyroid dysfunction is uncommon, and hyperthyroidism is described only in a minority of cases.^[4] If left undrained, a thyroid abscess may dissect through cervical planes or extend into the thoracic cavity, potentially rupturing into the trachea or esophagus. When untreated, it carries serious risks, with a reported mortality rate exceeding 12%.^[6,7]

CASE REPORT

This case report was prepared in accordance with the CARE (Case Report) guidelines.^[8] The patient and her legal guardian gave consent for the description of the reported case.

A previously healthy 14-year-old girl presented to the pediatric emergency department with pain in the anterior region of the neck. Although she denied oropharyngeal discomfort, she was initially treated for presumed bacterial pharyngitis with azithromycin and ketoprofen. Anterior neck pain persisted, accompanied by poor appetite, asthenia, and dizziness. The patient therefore returned to the emergency department, where a firm nodule measuring approximately 3 cm in diameter was palpated for the first time in the left thyroid lobe. This finding was subsequently confirmed by ultrasonography.

On the 7 day of symptoms, the patient was referred to the pediatric endocrinology outpatient clinic, already with thyroid function tests, serologies, and imaging studies requested. At that time, she reported cervical pain, goiter, worsening loss of appetite, asthenia, and insomnia. Physical examination revealed unintentional weight loss of 5 kg; she appeared pale, prostrated, and malnourished (body mass index: 12.89 kg/m², weight: 36.4 kg, and height: 168 cm). The thyroid gland was enlarged, firm, painful, and warm on palpation, with the presence of a hardened nodule in the left lobe, painful on palpation, poorly defined, measuring approximately 4.5 × 3 cm. The skin appeared slightly warm. The vital signs recorded at this evaluation were heart rate of 88 bpm in the supine position; blood pressure of 120/80 mmHg in the dorsal decubitus position and 110/75 mmHg in the seated position; and peripheral oxygen saturation of 94% on room air. On cardiac auscultation, heart sounds were rhythmic and normophonetic, without murmurs. Peripheral pulses were full and symmetrical. On pulmonary auscultation, vesicular breath sounds were present bilaterally, without adventitious sounds. The abdomen showed no abnormalities on physical examination. Laboratory and imaging findings are summarized in Tables 1 and 2. Thyroid function tests showed suppressed thyroid-stimulating hormone (TSH) and elevated free thyroxine (FT4) consistent with hyperthyroidism secondary to thyroiditis. Thyroid autoantibody and thyroglobulin levels were measured and were within the normal range (thyrotropin receptor antibody: 0.10 IU/L; anti-thyroperoxidase antibody [anti-TPO]: 28 IU/mL; thyroglobulin: 25.60 ng/mL; anti-thyroglobulin: 1.30 IU/mL). Serologies for cytomegalovirus, toxoplasmosis, rubella, and human immunodeficiency virus were negative for acute infection. In the context of significant biochemical thyrotoxicosis and before definitive diagnostic clarification, methimazole (30 mg/day) was initiated briefly and discontinued once AST was confirmed.

Five days later, she experienced worsening cervical pain, fever, and increased local heat. She was re-evaluated in the pediatric emergency department, and a neck computed tomography scan revealed a heterogeneous nodule occupying the left lobe and isthmus, predominantly hypodense, with peripheral post-contrast enhancement, septations, and cystic areas, measuring 62.7 mL in volume, and causing tracheal deviation [Figures 1 and 2]. She was hospitalized and started on intravenous ceftriaxone, corticosteroids, and supportive therapy. After 30 h of antibiotics, ultrasound-guided drainage removed 60 mL of purulent material. Cytology demonstrated turbid material with marked cellularity (664,000 nucleated cells/mm³) and neutrophilic predominance (80%), without atypia. Bacterioscopy by Gram stain and culture of the thyroid abscess was negative. On the thyroid ultrasound performed after the procedure, architectural distortion of the left lobe was observed, consistent with post-surgical manipulation, along with a small anechoic cystic collection, without increased vascular flow on Doppler study. On the 5^th-day post-drainage, symptoms recurred, and surgical re-intervention yielded an additional 60 mL of pus. Cultures from both procedures showed no bacterial growth.

Close

Figure 1:

Thyroid ultrasonography demonstrating a nodule with heterogeneous contents.

Export to PPT

Close

Figure 2:

(a) Axial computed tomography image showing a heterogeneous hypodense lesion in the left thyroid lobe with peripheral post-contrast enhancement, septations, and cystic areas. (b) Sagittal computed tomography image demonstrating the extent of the lesion and associated tracheal deviation. Arrows indicate the area of abscess formation and tracheal displacement.

Export to PPT

Forty-eight hours after the second drainage, the patient showed significant clinical improvement, with a reduction in asthenia and improved appetite. Methimazole was discontinued after 12 days of use due to bradycardia and near-syncope, occurring shortly after the second drainage procedure. In total, she received 15 days of antibiotic therapy and remained hospitalized for 17 days and was discharged after full clinical recovery. During the clinical course, a progressive increase in inflammatory markers was observed, with C-reactive protein ranging from 0.40 to 30.5 mg/dL and leukocyte counts between 10,040 and 24,640/mm³, followed by a decline after abscess drainage and antibiotic therapy. The blood culture and the abscess culture were negative.

Forty days after symptom onset, she was asymptomatic, with a weight gain of 2.3 kg. Thyroid examination revealed a mildly enlarged gland (approximately 1.5 × normal), slightly firm parenchyma, and no palpable masses or nodules. The last thyroid ultrasound, performed later after the completion of hospital treatment, showed the thyroid gland with reduced dimensions, preserved echotexture, no nodular lesions, and Doppler study without significant abnormalities. One year after the event, she remained asymptomatic, with no recurrence of infection or thyroid dysfunction.

DISCUSSION

In this report, we describe a previously healthy adolescent whose thyroiditis progressed to a large thyroid abscess associated with transient hyperthyroidism, a presentation seldom reported in the pediatric population. Thyroid infections are rare due to the gland’s intrinsic resistance to microbial invasion, attributed to its rich vascular supply, high iodine content, and fibrous capsule.^[1] AST is even less frequent, representing fewer than 0.7% of surgical thyroid conditions.^[3,4] In children, AST and thyroid abscesses are typically linked to congenital anomalies such as pyriform sinus fistulae and branchial arch remnants.^[5]

Most reported cases occur in euthyroid individuals; however, transient hyperthyroidism has been documented in a minority of pediatric cases [Table 2].^[4,9-12] The mechanism is thought to involve follicular disruption caused by intense inflammation or bacterial invasion, leading to acute hormone release. In our patient, the onset of thyrotoxicosis, followed by spontaneous normalization, supports this pathophysiology. Despite the large volume of purulent material drained on two occasions, both cultures were negative. This finding has been described previously,^[6] particularly when sampling occurs after antibiotic exposure, as in the present case.

Management of thyroid abscesses typically combines systemic antibiotics with percutaneous or surgical drainage.^[7,11] Although percutaneous drainage is effective in most cases, recurrence may occur, especially in multiloculated collections or in the presence of underlying anatomical anomalies. In the case described, the need for sequential drainage likely reflected the large volume and compartmentalized nature of the abscess. The absence of recurrent disease at 1-year follow-up and the normalization of thyroid function reinforce the effectiveness of timely intervention and close monitoring.

This case highlights important diagnostic challenges. Nonspecific early symptoms—neck pain, fever, weight loss, and asthenia—may mimic pharyngitis or subacute thyroiditis, delaying appropriate evaluation. In addition, the coexistence of hyperthyroidism may lead clinicians to prioritize autoimmune or subacute etiologies over infectious ones. Awareness of this possible presentation is essential to avoid under-recognition.

The strengths of this report include detailed clinical characterization, comprehensive laboratory and imaging documentation, and long-term follow-up demonstrating complete recovery. A limitation is the inability to isolate a causative microorganism, restricting the etiological interpretation; however, this is a common finding in AST and does not preclude diagnosis.^[6]

Overall, this case contributes to the limited literature on thyroid abscess with transient hyperthyroidism in adolescents; underscores the need for thorough evaluation of painful cervical swelling with thyrotoxicosis; and reinforces the importance of early imaging, interdisciplinary management, and prolonged clinical follow-up.

CONCLUSION

This case illustrates an uncommon presentation of AST in a previously healthy adolescent, characterized by a large thyroid abscess and transient hyperthyroidism. The overlap of early nonspecific symptoms and thyrotoxicosis may delay recognition, underscoring the need to consider thyroid infection in painful cervical swelling with inflammatory signs. Sequential drainage combined with antibiotic therapy resulted in complete clinical and biochemical recovery, and no recurrence was observed at long-term follow-up. Awareness of this presentation may facilitate earlier diagnosis, appropriate management, and improved outcomes in similar pediatric cases.