A 45-year-old male patient presented to the Hangzhou Red Cross Hospital (Hangzhou, Zhejiang, China) with a painless swelling in the left side of the neck that had gradually increased in size over two weeks. There was no complaint of dysphagia or dyspnea. The patient did not report any history of fever, coughing or hemoptysis, but complained of weight loss of 4 kg within the prior three months. The patient had no past or family history of tuberculosis. Upon examination, a solid, non-tender, 40x30-mm ill-defined mass was present in the left lobe of the thyroid. The cervical lump moved with deglutition, and no enlargement of the regional lymph nodes was observed. The white cell count in the peripheral blood was 10.9x109/l (normal range, 3.0-9.0x109/l), the neutrophil level was 45% and the erythrocyte sedimentation rate (ESR) was 60 mm/h. A thyroid hormonal profile revealed a euthyroid status. Human immunodeficiency virus testing was negative and investigations for infectious or inflammatory conditions were unremarkable. A chest X-ray revealed no pulmonary abnormalities, but the tuberculin test (1:10,000) was strongly positive.
US of the thyroid gland was performed using a real-time machine equipped with a 9-11 MHz probe (Philips, Amsterdam, Netherlands). US examination revealed a 34x27x24-mm, ovoid-shaped mass in the left lobe of the thyroid gland. The thyroid lesion was inhomogeneously hypoechoic, with ill-defined margins. An anechoic area with internal hyperechoic spots was present within the mass (Fig. 1A). Color Doppler examination revealed punctate or linear flow signals around the nodule with no intralesional vascularization (Fig. 1B).
The patient's general condition worsened three days after admission. There had been an increase in the size of the swelling, associated with a 37-38 C low-grade fever. A repeat US examination demonstrated that the mass in the left lobe of the gland had increased in volume to 65x35x38 mm. The lesion partially protruded from the upper pole of the left thyroid lobe (Fig. 2A). Compression with the probe and positional changes demonstrated the presence of liquid within the mass. Blood flow signals were observed by color Doppler examination around, but not inside the lesion (Fig. 2B). A US-guided fine-needle aspiration (FNA) biopsy of the thyroid mass yielded a thick, caseous and bloody material (Fig. 2C and D). Microscopic examination revealed the presence of follicular epithelial cells in flaked or honeycombed formations on a bloody background, together with clusters of purple-stained colloid and a field of granular caseous necrosis (Fig. 2E). In order to obtain a histological diagnosis, a US-guided CNB of the adjacent solid tissue was performed with a 21-gauge cutting needle. Histopathological examination revealed that multifocal granulomatous nodules were distributed in between atrophic thyroid follicles, chronic inflammatory cell infiltration and fibrous tissue proliferation (Fig. 2F). Acid-fast staining on frozen-sections did not indicate the presence of bacteria. However, the presence of multifocal granulomatous inflammation associated with caseous necrosis was strongly suggestive of tuberculous infection.
The patient was administered an oral three-drug regimen of antituberculous medication (0.3 g isoniazid, 0.6 g rifampicine and 0.2 g ciprofloxacine, once daily for a total of 3 months). Subsequent to three months of treatment, US demonstrated clinically significant shrinkage of the nodule down to 16x10x12 mm and the appearance of coarse calcifications inside the lesion. A repeat US examination was performed six months later without any marked changes in size, but with progressive loss of the definition of the nodule limits (Fig. 3). The patient remains without clinical symptoms at the time of writing.