Isolated thyroid abscess in early childhood

Abstract

Isolated thyroid abscess is a rare entity in early childhood. Among thyroid disorders, thyroid abscess or acute suppurative thyroiditis constitutes about 0.7%–1% of all cases. The thyroid gland is normally resistant to infections due to its well-enveloped capsule, rich blood supply, and high iodine content.

A child presented with tender neck swelling accompanied by fever for 3 days. Ultrasound of the neck showed features suggestive of left parapharyngeal abscess. Laboratory parameters including thyroid function test were within normal limits. Contrast-enhanced CT of the neck was done and showed an isolated thyroid abscess with no other abnormalities. The patient was started on intravenous antibiotics followed by incision and drainage of the abscess. The child improved symptomatically. This report discusses the differential diagnosis and management of this rare entity.

Background

Deep neck space infections are a rare entity in the paediatric age group. The deep neck space is divided into three layers: superficial, middle, and deep. Potential spaces of the neck are peritonsillar, submandibular, parapharyngeal, buccal, temporal/masticator, parotid, carotid, retropharyngeal, prevertebral, and anterior visceral space. According to the Kids’ Inpatient Database, the prevalence of deep neck space infection is 4.8 per 100 000 children.¹ Thyroid abscesses constitute around 0.7%–1% of all cases. They are a rare entity in the paediatric age group because the thyroid gland itself is highly resistant to infections due to its high iodine content, good blood supply, and well-enveloped capsule.² However, thyroid infections should be identified early and treated appropriately to prevent complications such as thyroid storm, airway obstruction, internal jugular vein thrombosis, parapharyngeal and retropharyngeal abscess, generalised sepsis mediastinitis, and necrotising fasciitis.^3–5 Infections in the visceral space involving the thyroid gland should raise suspicion of fourth branchial cleft cyst.

Case presentation

A patient in their early childhood with up-to-date immunisations and no comorbidities presented to the outpatient department of our hospital complaining of fever and a swelling in the front of the neck for 2 days, which was sudden in onset, gradually progressive, and painful, and was associated with difficulty in swallowing both solids and liquids for 1 day. The patient had no history of difficulty in breathing, cough, runny nose, or ear pain. On physical examination we found the patient to be febrile with a temperature of 100.3°F accompanied by tachycardia. On inspection of the neck [figure 1] we noted a 3×3 cm swelling in the anterior aspect of the left side of the neck that was mobile on deglutition and did not move on protrusion of the tongue. The swelling was ovoid and extended medially up to the midline and laterally up to the anterior border of the sternocleidomastoid muscle. It was located inferiorly 1 cm above the sternal notch and superiorly 2 cm below the hyoid bone. Its borders were not well defined. On palpating we confirmed our inspectory findings. A single 3×3 cm swelling that was smooth, globular, and firm with local warmth on the left side of the thyroid lobe and that moved with deglutition but not with protrusion of the tongue was noted. No palpable thrill or bruit was heard. No other palpable swellings or nodes were noted in the neck. No exudate was noted in the oropharynx. Ear and nose examination were normal.

Figure 1.

Swelling (3×3 cm) in the anterior aspect of the left side of the neck.

Investigations

Laboratory investigations were conducted and showed raised C-reactive protein of 15.7 mg/L and a normal leucocyte count. Thyroid function tests were normal. Radiological investigations were done, starting with an ultrasound of the neck that showed an ill-defined collection in the left paratracheal region 18 cc in volume and measuring 3.9×3.4×2.4 mm with internal echoes and separation with peripheral vascularity. Confirmatory diagnosis was done using contrast-enhanced CT of the neck [figure 2] which showed an ill-defined, multiloculated, peripheral enhancing collection measuring 2.9×3.2×4.5 cm and 21 cc in volume located in the left visceral space with an epicentre in the left thyroid gland extending superiorly up to the C3 vertebral body. Medially the swelling appeared to have a mass effect in the form of effacement of the left pyriform fossa, and laterally it appeared to displace the internal jugular vein, internal carotid artery, and sternocleidomastoid muscle, inferiorly extending to just below the left thyroid lobe up to the C7 vertebral body. No other cervical lymphadenopathy was noted. The patient was started on intravenous antibiotics with an injection of clindamycin 150 mg and was taken to the operating theatre for further management.

Figure 2.

Ill-defined, multiloculated, peripheral enhancing collection noted in axial and sagittal views in contrast-enhanced CT of the neck.

Differential diagnosis

Based on the clinical presentation and examination, a differential diagnosis of subacute thyroiditis, acute suppurative thyroiditis, branchial cleft cyst infection, soft tissue infection, lymphadenitis,⁶ cat scratch disease, parathyroid carcinoma, thyrotoxicosis, sarcoidosis, or cellulitis of the neck was possible (table 1).

Table 1.

Differential diagnosis of lumps in the neck

Differential diagnosis	Clinical presentation
Neck trauma	Pain, swelling; history of trauma
Cervical lymphadenitis	Swelling, pain, fever; palpable cervical lymph nodes with tenderness
Thyroglossal duct cyst	Swelling; moves with deglutition and protrusion of tongue
Neck infection/abscess	Swelling, pain, tenderness, fever, chills
Thyroid swelling (papillary, medullary, follicular)	Swelling in front of neck; moves with deglutition but not on protrusion of tongue; palpable thyroid nodules
Cystic hygroma	Swelling on lateral neck; soft and compressible; can be present since birth
Lymphoma	Non-tender swelling; firm to hard in consistency; night sweats, fever
Branchial anomalies	Swelling present since birth

The patient had no history of trauma and swelling since birth, and hence neck trauma, cystic hygroma, and branchial anomalies are less likely to occur. Based on the duration of the illness, it could be an infective aetiology due to neck infection.

Treatment

Intraoperative findings

Skin crease incision was done. The strap muscle was identified and retracted. There was difficulty identifying the plane as the structures were oedematous. Incision and drainage of the left thyroid abscess was done; 18 cc of pus were removed and sent for acid-fast bacilli (AFB) staining, GeneXpert testing, and bacterial culture. Necrotic tissue was removed and sent for histopathological examination (HPE).

Outcome and follow-up

Post procedure the wound healed well. Gram staining revealed a few gram-negative bacilli with pus cells. No organism was identified. GeneXpert was negative for Mycobacterium tuberculosis, and AFB stain was negative. The HPE report included fragments of fibromuscular tissue infiltrated by sheets of neutrophils admixed with lymphocytes, histiocytes, and necrosis, all of which were suggestive of abscess. Follow-up after 1 year showed no signs of recurrence [figure 3].

Figure 3.

Clinical imaging done postoperatively after 1 year of follow-up showed no signs of recurrence.

Discussion

The neck is a highly vascular structure. Thyroid abscesses are a rare occurrence in the paediatric age group. Congenital pyriform sinus fistula can be an important cause of this presentation; however, our immunocompetent patient presented with an acute onset neck swelling with fever and no other underlying pathology. Ultrasound was the preferred initial investigation as it allows guided aspiration, if required. It showed a collection in the left paratracheal space, leading to a diagnosis of left thyroid abscess. Following this, the patient was started on empirical antibiotic treatment with the lincosamide group. On further evaluation through contrast-enhanced CT of the neck we observed an ill-defined multiloculated lesion in the left visceral space with its epicentre in the left thyroid gland that was indicative of left thyroid abscess with no pyriform sinus fistula.

Acute suppurative thyroiditis is caused by major pathogens such as Staphylococcus aureus and Streptococcus pyogenes. Around 35%–40% gram-positive and gram-negative organism around 25% and anaerobes around 9%–12%^{7 8} have been reported. No organisms were isolated in our patient.

In a few studies, empirical treatment with intravenous antibiotics resulted in good improvement, with no requirement for incision and drainage. However, our patient required immediate drainage as he showed no signs of improvement with antibiotic treatment. After incision and drainage of the pus, the patient was started on parenteral clindamycin which resulted in improvement. Most patients with thyroid abscesses recover in 7–10 days. Patients should undergo regular follow-up and should also be informed about the risk of recurrence. Our patient was followed up for 1 year and showed no signs of recurrence.

Many studies have shown that there is an association between thyroid disorders such as thyrotoxicosis, subacute thyroiditis, autoimmune thyroiditis, and thyroid abscess and COVID-19 as a complication of the latter.⁹ As the patient presented to us during the COVID-19 pandemic and had no previous exposure to COVID-19, we had to bear COVID-19 in mind for this unexplained neck abscess.

Conclusions

Deep neck space infections, especially visceral space infections, are rare and even rarer in the paediatric age group. Any such infections involving only the thyroid gland should raise suspicion about an underlying thyroid anomaly or abnormality. Hence, proper investigation is required. In the paediatric age group, symptoms can sometimes be subtle and non-specific, resulting in a delay in diagnosis. It is important to understand the anatomical relations of the space as all vital structures are present. Hence, early diagnosis and intervention are key to prevent complications that could lead to airway compromise.

Patient's perspective.

• My son had fever and swelling in the neck. My doctors explained about the condition and need for investigations. They explained about the swelling in the neck and need for surgical management. I understood and signed an elaborately written consent in my own language. All the possible complications and adverse outcomes were explained by the doctors.

• My son was fine after the surgery and there were no complications. Overall, I am happy that my son got treatment at the earliest opportunity. Thanks to all the doctors, staff nurses, and technicians in the hospital who helped my son during his hospital stay. I am willing and happy to share my son’s case in this journal without revealing his identity, since this could be useful for future generations and also for future doctors.

Learning points

• Even though thyroid gland abscesses are rare, a high index of suspicion is required for early diagnosis and management.

• Treatment with the appropriate antibiotic and timely surgical intervention can confine the infection and prevent it from spreading to other visceral spaces of the neck.

Ethics statements

Patient consent for publication

Consent obtained from parent(s)/guardian(s).