Objective: The aim of the study was to evaluate the value of fine needle aspiration biopsy of the thyroid as a tool for diagnosing amyloid goitre and assess how amyloidosis affects thyroid tissue and thyroid function.
Methods: Clinical and laboratory evaluation of 50 patients with secondary systemic amyloidosis was done, and goitre was found in 38 of them. All 38 patients underwent thyroid aspiration biopsy. Tissue samples were stained with haematoxylin and eosin, May-Grünwald–Giemsa, crystal violet and Congo red.
Results: Of the 38 cases of amyloid goitre, 10 showed euthyroid sick syndrome, two showed primary hyperthyroidism, two showed hypothyroidism and one showed subacute thyroiditis. The serum levels of thyroid hormones and thyroid-stimulating hormone were normal in the remaining patients. Thirty-five of the 38 patients (92%) showed amyloidosis after thyroid aspiration. One of these patients had papillary carcinoma in addition to amyloid goitre. Ten patients underwent subtotal thyroidectomy, and one patient underwent total thyroidectomy after aspiration. Microscopic evaluation revealed that the thyroid parenchyma in all patients was largely replaced with amyloid and adipose tissue.
Conclusion: Fine needle aspiration of the thyroid is a valuable and sensitive method for diagnosing amyloid goitre, especially because it is a safe and easily performed procedure. Further, amyloid goitre has no significant influence on thyroid function even when it causes extensive parenchyma replacement.