Background and Objectives: preoperative differentiation of enlarged parathyroid glands may be challenging in conventional B-mode ultrasound. The aim of our study was to analyse qualitative and quantitative characteristics of parathyroid gland lesions, using multiparametric ultrasound protocol—B-mode, Colour Doppler (CD), and contrast-enhanced ultrasound (CEUS)—and to evaluate correlation with morphology in patients with hyperparathyroidism (HPT). Materials and Methods: consecutive 75 patients with 88 parathyroid lesions and biochemically confirmed HPT prior to parathyroidectomy were enrolled in the prospective study. B-mode ultrasound, CD, and CEUS were performed with the subsequent qualitative and quantitative evaluation of acquired data. We used 1 mL or 2 mL of intravenous ultrasound contrast agent during the CEUS examination. Correlation with post-surgical morphology was evaluated. Results: seventy parathyroid adenomas were hypoechoic and well contoured with increased central echogenicity (44.3%), peripheral-central vascularization (47%), and polar feeding vessel (100%). Twelve hyperplasias presented with similar ultrasound appearance and were smaller in volume (p = 0.036). Hyperplasias had a tendency for homogenous, marked intense enhancement vs. peripherally enhanced adenomas with central wash-out in CEUS after quantitative analysis. No significant difference was observed in contrasting dynamics, regardless of contrast media volume use (1 mL vs. 2 mL). We achieved 90.9% sensitivity and 72.7% specificity, 93% positive predictive value (PPV), 87.3% negative predictive value (NPV), and 87.3% accuracy in the differentiation of parathyroid lesions prior to post-processing. In a quantitative lesion analysis, our sensitivity increased up to 98%, specificity 80%, PPV 98%, and NPV 80% with an accuracy of 96.4%. Conclusions: CEUS of parathyroid lesions shows potential in the differentiation of adenoma from hyperplasia, regardless of the amount of contrast media injected. The quantitative analysis improved the sensitivity and specificity of differentiation between parathyroid lesions. Hyperplasia was characterized by homogeneous enhancement, fast uptake, and homogeneous wash-out appearance; adenoma—by peripheral uptake, central wash-out, and reduced hemodynamics. The use of CEUS quantification methods are advised to improve the ultrasound diagnostic role in suspected parathyroid lesions.

This report represents an unusually large parathyroid carcinoma (PC) mimicking thyroid nodule recurrence after hemithyroidectomy. PC is a rare endocrine malignancy accounting for less than 1% of hyperparathyroidism cases. This is the first case report where contrast-enhanced ultrasound (CEUS) was performed on a PC. A 63-year-old female presented with an enlarged mass on the left side of the neck. In 2012, left-side hemithyroidectomy was done due to a benign goiter. In 2020, laboratory analysis showed markedly elevated parathyroid hormone and calcium. Multiparametric neck ultrasonography was performed including B-mode, color Doppler, shear wave elastography, and CEUS. Computed tomography revealed an irregular mass in proximity to the trachea, esophagus, and dislocation of the common carotid artery. Perifocal fatty tissue appeared normal. Scintigraphy displayed a suspected parathyroid tumor or a suspected left lobe nodule of thyroid. Based on the biochemical diagnosis of primary hyperparathyroidism and radiological examinations, a suspected parathyroid tumor was considered. Intraoperative findings demonstrated an unusually large 9 × 6 cm tumor (84 g) adjacent to the common carotid artery anterolaterally and the recurrent laryngeal nerve medially. Pathohistological examination revealed a tumor solid in structure, with focal necrosis penetrating the capsule. Immunohistochemical analysis was positive for chromogranin, CD56, and Ki-67 (8–10%) and negative for CK20 and CK7. The morphological and immunohistochemical results correspond to PC. PC is a challenging diagnosis requiring a multidisciplinary approach, especially in the case of previous neck surgery. The only curative treatment for PC is radical surgery. Lifelong monitoring of PCs is mandatory due to the high recurrence rate.

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