Atypical ultrasound features of parathyroid tumours may bear a relationship to their clinical and biochemical presentation

OBJECTIVES To describe atypical ultrasound features of parathyroid lesions and correlate them with clinical presentation and histopathology. MATERIALS AND METHODS Retrospective review of 264 patients with primary hyperparathyroidism who underwent ultrasound imaging prior to parathyroidectomy was performed. Patients with atypical ultrasound findings (n = 26) were identified; imaging findings were correlated with clinical presentation and histopathology. RESULTS Twenty-one (80 %) lesions were adenomas, two (8 %) were adenomas with cellular atypia, and three (11.5 %) were carcinomas. Seventeen (65 %) lesions showed cystic change; five (19 %) of them had >50 % cystic change. These lesions were adenomas with cystic degeneration. Cystic degeneration had significant positive correlation with the lesion size and PTH level, but cystic adenomas correlated negatively with lesion weight. Six (23 %) lesions were isoechoic and one (4 %) was hyperechoic; histology predominantly revealed haemorrhage, hyalinisation and fibrosis; one lesion showed fat deposition and another had multiple granulomas within the adenoma. Twenty (83 %) lesions had heterogeneous echotexture and showed combinations of acinar dilatation, necrosis, haemorrhage and fibrosis. Heterogeneous lesions tended to be significantly larger and heavier, and they were associated with higher PTH levels. Four (15 %) lesions had calcifications. Scintigraphy was concordant in 22 (96 %), n = 23. One scintigraphy-negative lesion was a cystic parathyroid adenoma. CONCLUSION Atypical ultrasound features of parathyroid lesions pose a diagnostic challenge. Awareness of these features would help improve lesion detection. TEACHING POINTS 1. Cystic change is significantly related to the size, weight and measured parathyroid hormone levels. 2. Cystic change in parathyroid tumours indicated a slightly higher risk of malignancy. 3. Heterogeneous parathyroid adenomas are larger in size and heavier, and they have higher PTH levels. 4. Awareness of atypical ultrasound features will improve preoperative clinical prediction.