Serial changes in ultrasound-guided fine needle aspiration cytology in subacute thyroiditis

OBJECTIVE: To elucidate the serial cytologic presentations Of subacute thyroiditis (SAT) with ultrasound-guided needle aspiration (FNA). STUDY DESIGN: Nine patients with clinically evident SAT were recruited; serial sonography and ultrasound-guided needle aspiration cytology were performed. RESULTS: Sixty-one follow-up examinations were obtained in nine patients. The follow-up RANGED from 1 to 5 months (mean, 3.3). Initial sonographic presentations revealed focal hypoechogenicity in three patients and multiple hypoechogenicity in six. Initial cytologic findings showed chiefly enlarged, degenerated follicular cells with prominent nucleoli, lymphocytes, colloid substance, multinucleated giant cells and neutrophils. Regression of sonographic hypoechogenicity paralleled the disappearance of acute inflammatory cells and enlarged, degenerated follicular cells and the appearance of cohesive follicles. CONCLUSION: Improvement of SAT in sonography is fairly parallel to that in cytology even though there is a lng of improvement in the latter. Smear pattern is also related to the clinical stage of SAT. Ultrasound-guided FNA is a convenient method of obtaining sufficient and representative specimens in patients with SAT.