当科で経験した副甲状腺癌の2例

Two cases of parathyroid cancer

はじめに

　原発性副甲状腺機能亢進症の原因の大部分は副甲状腺腺腫であり，副甲状腺癌が原因である頻度は1％以下である。術前の画像検査で明らかな周囲組織への浸潤傾向や転移巣が認められない場合は，術前に副甲状腺癌と判断することは非常に困難とされる^1）。今回われわれは，術前に診断しえなかった副甲状腺癌症例を2例経験したので，文献的考察を加えて報告する。

　Parathyroid cancer is extremely rare as a cause of renewed primary parathyroid function. We report two cases of parathyroid cancer. A woman in her 40 s was found to have a mass lesion in the back of the right lobe of the thyroid gland on positron emission tomography in our neurology department. Hypercalcemia was observed, and the intact parathyroid hormone（PTH）level was high. Resection was performed for parathyroid adenoma, but the postoperative histopathological diagnosis revealed parathyroid cancer. A man in his 70 s was referred to our hospital because of hypercalcemia. He underwent surgery for primary hyperparathyroidism due to a parathyroid adenoma. A slight tendency to adhere to the surrounding tissue was observed during the surgery. He was diagnosed with parathyroid cancer based on the postoperative histopathological diagnosis. In both cases, a rapid intraoperative pathological diagnosis revealed an adenoma, but the final histopathological diagnosis was cancer. It was difficult to distinguish between these two conditions.