Unmasking primary thyroid tuberculosis - A rare but deceptive diagnosis: A case report with review of literature

INTRODUCTION AND IMPORTANCE: Thyroid tuberculosis is a rare condition, even in regions where tuberculosis (TB) is more common, possibly due to the thyroid gland's relative immunity. Diagnosing thyroid TB can be challenging as the clinical signs are often nonspecific. CASE PRESENTATION: A 75-year-old male presented with a swelling in the midline of the neck with an abscess in the lower portion of the swelling. Thyroid function tests were normal, and the tuberculin skin test returned positive. USG of the neck showed heterogeneous hypoechoic collection in the left lobe of thyroid, with surrounding inflammation and multiple subcentimetric lymph nodes in right upper, mid and lower jugular region showing necrosis. FNA revealed mixed inflammatory infiltrate predominantly neutrophils with lympho-histiocytic clusters in necrotic background. No signs of tuberculosis were detected in other organs. Based on these findings, primary thyroid tuberculosis was diagnosed. The patient was started on anti tubercular treatment resulting in a favorable clinical outcome. CLINICAL DISCUSSION: TB rarely presents as a thyroid mass. A history of prior tuberculosis, the presence of cervical lymphadenopathy, and an elevated erythrocyte sedimentation rate (ESR) can support the diagnosis. Fine-needle aspiration cytology (FNAC) is an effective diagnostic method. CONCLUSION: Although rare, tuberculosis of the thyroid must be considered before deciding on a surgical management for disorders of the thyroid. Treatment typically involves anti-tuberculosis medications, but drainage may be needed for large abscesses, and thyroidectomy might be required if the FNAC results are inconclusive.