Endocrine Abstracts

Introduction: Amyloidosis refers to a variety of conditions in which amyloid proteins are abnormally deposited in organs and/or tissues. Clinically significant enlargement of the thyroid owing to amyloid deposition is a rare occurrence.

Case report: 58-year-old female referred to endocrinology clinic presenting with increasing dyspnea, dysphagia and visible swelling at the base of the neck for the last 6 months. She had been diagnosed with rheumatoid arthritis six years ago but had not used the prescribed medication regularly; she is on regular nonsteroidal anti-inflammatory drugs. Physical examination revealed: BP, 130/70 mmHg; HR, 100 bpm; RR, 22/min. Temperature, 37°C. Enlarged thyroid gland firm in consistency with multiple nodules on palpation. Laboratory test results included: TSH, 1.24 IU/dl (normal range, 0.4–4.0); free T3,2.2 ng/dl, free (N,2.3–4.4) free T4, 1.21 ng/dl (normal range, 0.7–2) glucose, 90 mg/dl, albumin; 3.6 g/dl, creatinine, 1.7 mg/dl; 24-h proteinuria, 1.9 g/day. Both of the thyroid lobes are enlarged in the ultrasound examination. The right lobe showed multiple nodules of 45–50 mm size, with areas of cystic degeneration. Renal ultrasound examination revealed grade II nephropathy. Echo heart showed impaired left ventricular filling, sclerotic aortic valve, and normal ejection fraction.Because of compressive symptoms, a computed tomography (CT) scan was performed before surgery, showing multinodular goiter with no tracheal compression. Total thyroidectomy was done Microscopic study of the specimen showed extensive infiltration of thyroid parenchyma by an amorphous expansive amorphous eosinophilic substance deposition and lipid infiltration in the whole thyroid gland. On Congo red dye staining, amyloid deposition was stained red in the interstitial space and it showed an apple-green birefringence with the polarizing microscope with no neoplastic cells. Renal biopsy was performed due of kidney involvement, showing kidney infiltration by amyloid with marked tubulo- interstitial fibrosis.

Conclusion: Amyloid goiter is an atypical presentation of an already rare disease. A high index of attentiveness should be kept whenever amyloid deposits are seen on fine needle aspiration cytology, as they are also established in medullary carcinoma. The confirmative diagnosis rested on the histopathology of the specimen.