Thyroid tuberculosis: an unexpected diagnosis

Mycobacterium tuberculosis (MTB) is an aerobic bacillus responsible for tuberculous infection. The the thyroid gland being affected by MTB is a rare condition. A 71-year-old woman had 6 months of slight cervical discomfort. Her neck ultrasound showed, at the right lobe of the thyroid, a dominant heterogeneous nodule of 18 mm and homolateral lymph nodes with suspicious ultrasonographic features. The patient underwent fine-needle aspiration, the results of which were non-diagnostic (thyroid nodule) and reactive pattern (lymph node). A total thyroidectomy was performed and a lymph node was sampled for extemporaneous examination. Surprisingly, necrotising granulomas were documented. The diagnosis was definitely established by a positive culture of the lymph node tissue and molecular detection of MTB. Pulmonary involvement was excluded and she was started on antituberculous agents. In the absence of systemic, specific complaints or history of exposition, histopathology and culture of MTB remain a key step for the diagnosis.