Background: Preoperative evaluation is very important for the diagnosis of parathyroid carcinoma. However, fine needle aspiration cytology(FNAC) is not recommended because of its possibility of tumor implantation. So only clinical data have been considered as usable indicator of malignancy. We reported high Depth-Width(DW) ratio (≧1) of a tumor is an important indicator of malignancy. Due to its high sensitivity, the specificity of DW ratio was slightly poor because large part of benign tumors sometimes showed high DW ratio. So we introduced ultrasound Elastography, in addition to the normal B-mode ultrasound evaluation including measurement of DW ratio, to improve the specificity.
Material and Methods: First of all, we performed B-mode ultrasound examination for patients with parathyroid enlargement and calculated its DW ratio. Malignancy was suspected for a tumor with DW ratio≧1 or a very large tumor that its DW ratio could not be calculated. We used thyroid gland as a control tissue, and compared the elasticity between the two. We made diagnosis between benign or malignant tumors based on the elasticity of parathyroid compared to thyroid gland. The operation was performed based on the diagnosis.
Results: Among the four cases which were suspected of malignancy by B-mode ultrasound examination, two cases were soft and the other two cases were hard compared to thyroid gland. Pathological examination of these four cases showed that the former two cases were adenoma and the later two cases were adenocarcinoma.
Conclusion: Ultrasound Elastography is easy to perform and offers additional information to conventional ultrasound for parathyroid carcinoma detection.