Partially Cystic Thyroid Nodules: Ultrasound Findings of Malignancy

OBJECTIVE: To seek for the ultrasound (US) findings of partially cystic thyroid nodules that are associated with malignancy. MATERIALS AND METHODS: We reviewed the US characteristics of 22 surgically confirmed partially cystic papillary carcinomas, and compared them with those of 80 benign partially cystic nodules. The review cases were selected in a random order from a total of 1029 partially cystic nodules that were diagnosed with an US-guided fine needle aspiration biopsy over a period of 8 years (June 2003 to October 2010) at our institution. RESULTS: In partially cystic thyroid nodules, a taller-than-wide shape (100%, p < 0.001) and spiculated or microlobulated margin (58.3%, p = 0.003) were significantly associated with malignancy. In terms of internal solid portion of the nodule, eccentric configuration (68.0%, p < 0.001), non-smooth margin (81.3%, p < 0.001), hypoechogenecity (30.0%, p < 0.042), and microcalcification (89.5%, p < 0.001) were more frequently demonstrated in malignant nodules than benign ones. CONCLUSION: In partially cystic thyroid nodules, understanding the characteristics of US findings is important to make a precise diagnosis of malignant nodules.