Purpose: To identify the variant features encountered in parathyroid abnormalities and document those suggesting malignant change.
Materials and methods: Data were collected from a cohort of patients who underwent investigation for primary hyperparathyroidism over a 10-year period. Ultrasonographic features: shape, presence of calcification, cystic changes, heterogeneous echogenicity, vascularity, capsular thickening, local invasion, and vascularity were reviewed retrospectively and were used to correlate with final histological findings.
Results: One hundred forty-seven patients with histology and concurrent ultrasonographic scans were reviewed, and divided into benign parathyroid lesions (nodular hyperplasia (n = 44), adenoma (n = 93)) and parathyroid carcinoma (n = 10). Parathyroid carcinomas were significantly larger than benign parathyroid lesions (P = 0.030). Benign parathyroid lesions showed variant sonographic features: irregular shape (16.8%), heterogenous echogenicity (24.1%), calcification (1.5%), capsular thickening (1.5%), and cystic change (19.7%). A significantly higher proportion of parathyroid carcinomas demonstrated heterogenous echogenicity (P = 0.022), capsular thickening (P = 0.023), and infiltrative margin (P < 0.0001) than benign parathyroid lesions. Of the 137 benign parathyroid lesions, 38 (27.7%), 76 (55.5%), 23 (16.8%) were avascular, vascular, and hypervascular, respectively. Of the 10 parathyroid carcinomas, 4 (40%), 3 (30%), and 3 (30%) of lesions were avascular, vascular, and hypervascular, respectively. The vascularity of the lesions did not differ significantly between the parathyroid carcinoma and benign parathyroid lesions (P = 0.281).
Conclusion: Ultrasonographic features such as irregular shape, heterogeneous echogenicity, cystic change, and vascularity are nondiscriminatory features between benign or malignant lesions. Large lesion size together with the presence of calcification, capsular thickening, or infiltrative margin strongly raises the suspicion of a malignant parathyroid lesion, and management should be altered.
Keywords: Color Doppler; parathyroid adenoma; parathyroid carcinoma; primary hyperparathyroidism; sonography; ultrasound.