Thyroid abscess is an uncommon infectious pathology in children because of the anatomical and physiological characteristics of the thyroid gland which make it resistant to infection. The thyroid gland has fibrous capsule, high iodine content, rich vascularity, extensive lymphatic drainage, and anatomical isolation by fascial planes, all these features protects it from infection prima facia.[1] Acute suppurative thyroiditis (AST) represents only 0.1-0.7% of surgically managed thyroid lesions[7,8]. The progression to frank abscess formation is even rarer, particularly in children [9,10].However, known predisposing factors include congenital pyriform sinus fistula[11,12],pre-existing thyroid disease[13,14], immunodeficiency states[15,16],local trauma or instrumentation[17,18], upper respiratory tract infections[19,20]Though an uncommon pathology in pediatric age group, thyroid abscess needs to be considered as differential in acute tender neck swellings and managed promptly.

A previously healthy 5 years male child presented with complains of fever since 7 days and painful progressive swelling in midline of neck noticed since 5 days associated with skin erythema. There was no prior history of trauma or infection. On physical examination child was febrile with tender, fluctuant warm midline swelling of around 5 x 4 cm in the neck. There was no cervical lymphadenopathy and systemic examination was within normal limits. With provisional diagnosis of cervical abscess , patient was admitted , started on empirical intravenous antibiotics and planned for surgical incision and drainage under general anaesthesia. USG of neck revealed  a5 x 2.9 x 3.6 cm hypoechoic lesion with internal echoes  in thyroid gland suggestive of thyroid abscess.[Fig 1]Surrounding thyroid parenchyma was found normal and there was no evidence of pyriform sinus fistula. On hemogram, leukocytosis(Total leukocyte count-18500/ μL) was found. Thyroid function test were within normal limits, HIV screening was negative. Incision and drainage was done under general anesthesia and pus was sent for culture and sensitivity.[Fig 2,3] Pus culture yielded methicillin-sensitive Staphylococcus aureus and antibiotic adjustment based on sensitivity. There was uneventful post-operative recovery with complete resolution of symptoms and no recurrence at 6-month follow-up. Thyroid function were maintainednormal.

 Acute suppurative thyroiditis (AST) is a rare clinical event1 and an uncommon form of thyroiditis [2]. The progression of the condition to thyroid abscess is equally unusual[3]. Both AST and thyroid abscess represent 0.1 to 0.7% of thyroid lesions managed surgically.[4] A tender thyroid lesion is the hallmark of AST but other causes do exist such asde Quervain thyroiditis (commonest), acute hemorrhage into a cyst or thyroid nodule, a rapidly enlarging thyroid carcinoma, or radiation thyroiditis [5,6]. Certain anatomical features make thyroid resistant to infection including: total encapsulation of the gland, its secluded anatomic position, an iodine-rich environment, extensive lymphatic drainage, and good blood flow from bilateral superior and inferior arteries. Haematogenous spread from a distal site of infection is a common cause of thyroid infection; however the exact infectious source or pathway may not be found. In index case, exact cause of infection was not known. Other causes of AST may be a congenital thyroid gland pathology such as pyriform sinus fistula with secondary infection,[3] trauma such as fine-needle aspiration [7] and foreign bodies. None of this was however demonstrated in the index case. AST has also been associated with immunosuppression, especially human immunodeficiency virus [6], however a retroviral screen in our patient was negative. Although African Health Sciences Vol 10 No 1 March 2010 103 Staphylococci and Streptococci have been described as the most frequent causes of AST,[7] many other organisms such as Aspergillus, Brucella, Klebsiella, Eikenella, Salmonella, and Acinetobacter have been identified in infection of the thyroid gland and oftentimes the infection is polymicrobial.[6] Thyroid abscess have been observed to be more usual in females than males[7] with a wide age range of 16 days to 79 years, [8] with the left side of the gland more commonly involved. Thyroid abscesses are usually preceded by upper respiratory tract infection or middle-ear infections.[9] Clinical signs include tenderness of the gland, dyspnea, pain, hoarseness, dysphagia, fever, and chills. Few patients may be asymptomatic and diagnosed on laboratory results indicating infection such as leukocytosis, elevated erythrocyte sedimentation rate and thyroid scintigraphies showing hypo-functional areas with reduced uptake.[10] Plain roentgenogram of the neck may show tracheal displacement, ultrasonography and computerized tomography may identify the underlying structure and extent of the abscess. A fine-needle aspiration can be done to confirm the diagnosis of thyroid abscess and to determine the responsible organism. Broad-spectrum antibiotic therapy covering aerobic, anaerobic, and oral flora should be started prior to surgery and changed once antibiotic sensitivity is available. Treatment includes incision and drainage, combined with culture and appropriate antibiotic therapy. Thyroid abscess may lead to complications like destruction of the thyroid or parathyroid glands, internal jugular vein thrombophlebitis, local or hematological spread to other organs, sepsis, and even abscess rupture or fistula formation into the esophagus or trachea.[9] Index case was found to have Staphylococcus aureus as pathogen. High index of suspicion for thyroid abscess need to be there, in cases of fever of unknown origin in children.

There are no conflicts of interest.

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