What is tuberculosis (TB) thyroiditis, and how is it suspected, diagnosed, and managed?

From the Guidelines

Tuberculous thyroiditis is a rare form of extrapulmonary tuberculosis that should be suspected in patients with a painless thyroid mass or abscess, especially those with constitutional symptoms or a history of TB elsewhere in the body. When to suspect TB thyroiditis includes patients presenting with a painless thyroid mass or abscess, especially those with constitutional symptoms like fever, weight loss, and night sweats, or with a history of TB elsewhere in the body. Diagnosis requires a high index of suspicion and involves:

• Fine-needle aspiration cytology (FNAC) of the thyroid lesion, which may show caseating granulomas, acid-fast bacilli on Ziehl-Neelsen staining, or positive cultures for M. tuberculosis
• Additional diagnostic tools include PCR for TB DNA, ultrasonography showing hypoechoic lesions, and chest X-ray to identify pulmonary TB, as recommended by the American College of Radiology 1 Management consists of standard anti-TB therapy with a 2-month intensive phase of isoniazid, rifampin, pyrazinamide, and ethambutol, followed by a 4-month continuation phase with isoniazid and rifampin, as outlined in the American Thoracic Society guidelines 1. Surgical intervention may be necessary for large abscesses requiring drainage or for diagnostic confirmation when FNAC is inconclusive. Thyroid function tests should be monitored as TB thyroiditis can occasionally cause hypothyroidism or hyperthyroidism. For further learning, I recommend reviewing case series in endocrinology journals, tuberculosis textbooks focusing on extrapulmonary manifestations, and clinical guidelines on tuberculosis management from major infectious disease organizations, which provide comprehensive information on diagnosis and treatment protocols for this uncommon condition.

Some key points to consider in the management of TB thyroiditis include:

• The importance of initiating treatment with a 4-drug regimen, as recommended by the American Thoracic Society 1
• The need for regular monitoring of thyroid function tests, as TB thyroiditis can cause hypothyroidism or hyperthyroidism
• The potential for surgical intervention in certain cases, such as large abscesses requiring drainage
• The importance of considering the patient's overall clinical presentation and medical history when making a diagnosis and developing a treatment plan.

In terms of specific treatment protocols, the American Thoracic Society recommends a 2-month intensive phase of isoniazid, rifampin, pyrazinamide, and ethambutol, followed by a 4-month continuation phase with isoniazid and rifampin 1. The American College of Radiology recommends chest radiography as the first-line imaging test for patients with suspected tuberculosis, with chest CT reserved for cases where radiography is nonrevealing or nondiagnostic 1.

Overall, the management of TB thyroiditis requires a comprehensive approach that takes into account the patient's overall clinical presentation, medical history, and treatment needs. By following established guidelines and considering the latest research and recommendations, healthcare providers can provide effective care for patients with this uncommon condition.

From the Research

Definition and Prevalence of TB Thyroiditis

• TB thyroiditis is a rare condition, even in countries with a high prevalence of tuberculosis 2.
• It can manifest in various ways and does not have specific symptoms characteristic only to thyroid tuberculosis 3.

When to Suspect TB Thyroiditis

• TB thyroiditis should be suspected in patients with a thyroid nodule, especially in communities where the prevalence of tuberculosis is high 2.
• It should be considered in the differential diagnosis of neck mass, particularly when localized swelling, cold abscess, or thyroid nodule with or without a cystic component are present 4.

Diagnosis of TB Thyroiditis

• Fine-needle aspiration cytology (FNAC) is a useful method in diagnosing tuberculous thyroiditis 2, 5.
• Histopathologic examination of surgical material is essential for diagnosis, and Erlich Ziehl Nelsen staining should be performed to identify bacilli 6.
• Microbiologic cultures can also be used to diagnose thyroid tuberculosis 6.

Management of TB Thyroiditis

• The choice of treatment should be medical antituberculous therapy 2.
• Surgery is limited after diagnosis, and preoperative diagnosis of thyroid tuberculosis is important to avoid unnecessary thyroid surgery 2, 3.
• Repeated puncture drainage procedures may be necessary in some cases 3.

Resources for Further Learning

• Review articles such as "Tuberculosis of the thyroid gland: review of the literature" 2 and "Thyroid tuberculosis with abnormal thyroid function--case report and review of the literature" 5 can provide a comprehensive understanding of the condition.
• Case reports like "Thyroid tuberculosis" 4 can offer insights into the clinical presentation and management of the disease.