[Tuberculosis of the thyroid gland mimicking thyroid carcinoma in the elderly]

A 76-year-old woman with a 10-year history of chronic glomerulonephritis was treated at a clinic after presenting with a gradual worsening of the renal function. The patient had no history of tuberculosis. She was subsequently hospitalized for uremic symptoms and treated with internal shunt insertion and dialysis. Thyroid ultrasonography was performed to screen for secondary hyperparathyroidism, which revealed a calcified thyroid mass and cervical lymph node swelling. Fine-needle aspiration biopsy was thus conducted to assess suspected thyroid cancer. The cytological findings showed few follicular epithelial cells, without any signs of malignancy. However, a diagnosis of thyroid cancer continued to be strongly suspected based on the imaging features. Total thyroidectomy and bilateral cervical regional lymph node dissection were therefore performed, and the pathological examination of the thyroidectomy specimen disclosed scattered epithelioid granulomas with caseous necrosis in the entire right lobe as well as the cervical lymph nodes. Based on these findings, the patient was diagnosed with thyroid tuberculosis. As the symptoms and imaging findings of tuberculosis are nonspecific in elderly patients, it is necessary to consider this disease in this population. We therefore propose the inclusion of thyroid tuberculosis in the differential diagnosis of elderly patients who present with malignant thyroid tumors on aspiration biopsy cytology, regardless of whether or not they have a previous history of tuberculosis.