Background: Amyloid goiter (AG) is an exceedingly rare cause of an enlarged thyroid gland associated to either primary or secondary forms of amyloidosis. We present the development of AG in a euthyroid patient with secondary Amyloid A (AA) amyloidosis, chronic kidney failure and a previous history of a spinal cord sarcoma.
Patient findings: The patient was a 59 year-old male who presented with a slowly progressive enlargement of both thyroid lobes, eventually causing significant tracheal displacement, dysphagia and dyspnea. The previous patient history, the spectacular size in addition to the lipomatous appearance on a cervical CT scan raised some concern that the lesion was in fact a slow-growing liposarcoma of the thyroid. A fine-needle aspiration biopsy identified scarce thyrocytes intermingled with adipose tissue fragments and multiple amyloid deposits. Following a total thyroidectomy, the pathology report was consistent with AG, a diagnosis supported by the occurrence of a remarkable adipose tissue metaplasia adjoined by atrophic follicles and findings of amorphous substances positive for Congo Red staining and Amyloid A (AA) protein immunoreactivity. Liposarcoma and medullary thyroid carcinoma was ruled out. The patient was discharged from further surgical follow-up, and is currently well.
Discussion and conclusion: AG should always be suspected in systemic amyloidosis patients with a pronounced enlargement of the thyroid gland. The entity can be suspected already by radiology, but the cytological and histological identification of amyloid deposits are key attributes for establishing the correct diagnosis.
Carl Christofer Juhlin, Fredrik Karlsson and Robert Bränström