Are there any specific ultrasound findings of nodular hyperplasia ("leave me alone" lesion) to differentiate it from follicular adenoma?

Among benign thyroid nodules, nodular hyperplasia (NH) is the most common and represents a "leave me alone" lesion with no requirement for further treatment, while follicular adenoma (FA) is a lesion that should potentially be removed due to the difficulty of differentiation from a carcinoma on a biopsy alone.,To evaluate whether there are specific ultrasound (US) findings for an NH to distinguish it from an FA.,Pathologically proven cases of benign thyroid nodules (95 cases: 53 NH, 42 FA) were reviewed retrospectively. The number of associated nodules, the nodule size, internal content, shape, margin, echogenicity, presence of peripheral halo, and calcification were analyzed using grayscale ultrasonography.,NHs were predominantly solid in 40 cases (75.5%) and predominantly cystic in 13 cases (24.5%), while FAs were predominantly solid in all cases (n=42, 100%) (P<0.001). A spongiform appearance was present exclusively in NH (9/53, 17.0%). For NH, 83.0% of the lesions (44/53) showed an isoechoic pattern. For FA, the lesions showed a variable echoic pattern, including a marked hypoechoic pattern (5/42, 11.9%), a hypoechoic pattern (22/42, 52.4%), and an isoechoic pattern (15/42, 35.7%) (P<0.001). The nodule size, shape, margin, presence of peripheral halo, and calcification did not show any difference between FA and NH.,The ratio of solid to cystic content, spongiform appearance, and echogenicity is a combination of US findings that may be helpful in distinguishing an NH from an FA, and may thereby help to avoid unnecessary fine-needle aspirations for "leave me alone" lesions.