Abstract Disclosure: J. Paz-Ibarra: None. M. Concepción-Zavaleta: None. A.P. Solis Pazmino: None. J. Somocurcio Peralta: None. Background: Amyloid goiter (AG) is a rare presentation of thyroid swelling, characterized by the presence of deposits of amyloid protein in the thyroid tissue, accompanied by fat deposition or thyrolipomatosis. It may occur in 50% and up to 80% of patients with primary and secondary amyloidosis, respectively. Currently, the treatment is surgical resection of the thyroid gland. The present study reports a case series of primary thyroidal nodular amyloid goiter diagnosed by fine-needle cytology (FNC). Clinical cases:There were 2 female and 1 male patient from Peru. All three patients had comorbidities prior to AG diagnosis. F1: 65 years old, history of Rheumatoid Arthritis, Sjogren’s disease nephron Angio sclerosis, and polycystic kidney disease. F2: 67 years old, history of rheumatoid arthritis, end-stage renal disease (ESRD), arterial hypertension. M1: 28-year-old man with a history of pulmonary tuberculosis, bronchiectasis, and ESRD on HD due to renal amyloidosis of 9 years' evolution. They reported dyspnea, dysphagia, and dysphonia. On their physical examination, they had a bilateral, firm, and diffusely enlarged thyroid gland. Her serum T3, T4, and TSH levels were all normal. The PAAF reported a colloid goiter (Bethesda II). A total thyroidectomy was performed, with no complications. An alcohol-fixed smear was stained with Congo red: the amyloid material appeared cherry red and it also showed apple-green birefringence when observed with a polarizing microscope. Conclusions: Secondary amyloidosis generally has a neoplastic origin or is secondary to chronic inflammatory diseases. The development of a giant goiter with compressive symptoms is the most common form of presentation and represents amyloid infiltration of the gland. Total thyroidectomy is the method of choice for both diagnosis and treatment of amyloid goiter. Histological evaluation of the resected thyroid gland is crucial to make a definitive diagnosis. Presentation Date: Saturday, June 17, 2023