Ultrasonography of cystic thyroid nodules: sonographic-pathologic correlation

Retrospectively the ultrasonographic findings of 153 surgically resected cystic thyroid nodules were reviewed. The pathologic findings in this series revealed that 86% were degenerating benign adenomas or adenomatous goiters, and 14% were malignant tumors. The sonographic appearance of these lesions was classified into 7 groups as follows: type I: entirely cystic (less than 1cm), type II: cystic(more than 1cm) [II(a)], and with small polyp or dome-like elevation on the cyst wall [II(b)], type III: larger cyst with projection (more than 1cm) into the lumen, type IV: cyst with a peripherally localized solid component, type V: irregularly mixed cystic and solid components, type VI: a solid mass with multiple crescentic cysts [VI(a)], or round cysts [VI(b)], type VII: a solid mass with only one or two cysts. Pathologic correlation revealed that malignancy in this series ranged from 80% in type III and V to only 4% in type II, where most of the lesions in this group were composed of granulation tissue in degenerating adenomatous polyps and cyst walls. Lesions in type IV showed malignancy rate of 40%. Type III showed characteristic sonographic findings seen in cystic papillary carcinomas (CPCs), with multiple punctate echogenic foci in large pedunculated projections. The typical psammomatous calcifications specific in this group were confirmed in 6 of the 8 type III CPCs. The multiple crescentic cysts in type VI(a) lesions were characteristic sonographic signs seen in adenomatous goiters, representing the pathologic finding of cysts forming around each of multiple adenomatous nodules in this group. Type VII represented non specific appearing lesions, included adenomas, adenomatous goiters, CPCs and follicular carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)