Researchers found that multinodular goiter could be the primary clinical manifestation secondary to amyloid light chain amyloidosis instead of medullary thyroid carcinoma (MTC), as published in Thyroid Research. This study highlights the importance of a solid understanding of the causes of systemic amyloidosis coupled with a thorough evaluation of the patient’s history and laboratory data to diagnose it as the etiology for goiter.

Patel and colleagues described the case of a 73-year-old male presenting with goiter and compressive symptoms of dysphagia and hoarseness. This patient with a history of pituitary adenoma, primary hyperparathyroidism, left adrenal nodule, and multiple endocrine neoplasia (MEN) syndrome was high on the differential diagnosis list. MTC is a common manifestation associated with MEN type 2 syndrome, therefore, MTC was also a possible diagnosis in the context of a multinodular goiter.

“Amyloid deposits can be seen in MTC and it was vital to rule this out with the negative calcitonin stain. As evidenced in this case and other case reports, we cannot confidently rely on fine-needle aspiration and histopathology of the resected thyroid tissue was needed for the definitive diagnosis,” the authors wrote. 


Continue Reading

Read more about MTC testing

Moreover, pathology revealed benign thyroid parenchyma with diffuse amyloid deposition in the thyroid and parathyroid glands that stained apple-green birefringence under polarized light on Congo Red stain. Immunochemical staining detected amyloid light chain amyloid deposition of the lambda type.

Bone marrow biopsy revealed an excess monoclonal lambda light chain of plasma cells consistent with a diagnosis of amyloid light chain amyloidosis secondary to multiple myeloma affecting the kidney, thyroid, parathyroid gland, and heart. This unique, complicated endocrine case emphasizes the importance of an extensive evaluation of a patient’s history and laboratory data to arrive at a diagnosis of amyloid light chain amyloidosis.

Goiters due to a large quantity of amyloid deposition known as amyloid goiter are very rare. It occurs in only 0.04% of patients with systemic amyloidosis. Otherwise, the differential for amyloid deposits in the thyroid is quite narrow. About 30% to 50% of patients with MTC have amyloid deposition, and very rarely, in microfollicular thyroid cancer and Riedel’s thyroiditis. It is crucial to rule out MTC as the etiology, especially in patients like these with a possible MEN type 1 syndrome.

Reference

Patel Chavez C, Morales Hernandez M, Kresak J, Woodmansee W. Evaluation of multinodular goiter and primary hyperparathyroidism leads to a diagnosis of AL amyloidosis. Thyroid Res. Published online April 20, 2022. doi:10.1186/s13044-022-00125-5