Thyroid tuberculosis with abnormal thyroid function--case report and review of the literature.

Objective: To report an extremely rare case of thyroid tuberculosis (TT) with abnormal thyroid function and to review the related literature.

Methods: We present the patient's history, clinical findings, laboratory test results, imaging examinations, cytological data, management, and follow-up. In addition, we perform a review of the previously published cases of TT and give special attention to those with hypothyroidism.

Results: A 45-year-old Indian man presented to the outpatient clinic with neck swelling and respiratory and constitutional symptoms. Cervical ultrasound revealed a thyroid nodule and a necrotic right cervical adenopathy. Fine-needle aspiration cytology (FNAC) was performed and purulent material was removed from thyroid and lymph node. In both specimens, the culture was positive for Mycobacterium tuberculosis complex, and a cytological examination revealed epithelioid cell granulomas and necrosis. Mycobacterium tuberculosis complex was also identified by sputum culture. Antibiotic testing revealed sensitivity to all first-line drugs. A diagnosis of disseminated tuberculosis with thyroid and cervical lymph node involvement was made. Thyroid function was consistent with subclinical hyperthyroidism that subsequently evolved to hypothyroidism, requiring thyroid hormone replacement, and reflected tuberculous thyroiditis. Anti-tuberculosis drugs were started with good therapeutic response.

Conclusion: TT is a rare condition and its association with thyroid function abnormalities is even rarer. To our knowledge this is the third report of hypothyroidism related to TT and the first to identify a period of hyperthyroidism preceding hypothyroidism. Despite its rarity, TT should be considered in the differential diagnosis of neck mass. FNAC is a useful procedure and thyroid function should be monitored.