An intra-thoracic follicular carcinoma of thyroid: An uncommon presentation

Follicular carcinoma of thyroid is the second most common type of carcinoma of thyroid, and it may metastasize to bone, lung, brain, and skin. However, the initial presentation of follicular carcinoma of the thyroid as a large intrathoracic mass without any symptoms of thyroid gland enlargement and dysfunction is very rare. We hereby report a case of a 50-year-old male who presented with chief complaints of chest and low back pain. Preliminary evaluation led to the provisional diagnosis of left-sided intrathoracic mass with vertebral metastasis which was suspected to be a case of bronchogenic carcinoma with distant metastasis. Surprisingly, transthoracic biopsy and histopathology revealed metastasis from follicular carcinoma of thyroid. This prompted us for a retrograde evaluation for a primary thyroid malignancy for which an ultrasound and contrast enhanced computed tomography (CECT) of the neck was done which confirmed the presence of a solitary thyroid nodule. Ultrasonography-guided fine-needle aspiration cytology of the nodule revealed follicular carcinoma of thyroid. Histopathological evaluation subsequent to total thyroidectomy revealed follicular carcinoma thyroid, further confirming the diagnosis. The patient was then referred to Department of Nuclear Medicine and Radiotherapy for radionuclide ablation and chemotherapy. We chose to report this case because of its rare presentation as a large intrathoracic mass and the retrograde diagnosis of follicular carcinoma of thyroid. To the best of our knowledge, this is the first report of such a rare case.