99mTcO4−シンチグラフィで高度集積を認めた耳下腺上皮筋上皮癌の1例

A case of epithelial-myoepithelial carcinoma that showed a high positive rate on 99mTcO4− scintigraphy

はじめに

　耳下腺上皮筋上皮癌は，唾液腺腫瘍のなかで1％未満と稀な組織型の腫瘍である。今回，^99mTcO₄⁻シンチグラフィ（以下，Tcシンチグラフィ）で高度集積を認めた耳下腺上皮筋上皮癌の1例を経験したので，文献的考察を加えて報告する。

　Epithelial-myoepithelial carcinoma is a rare tumor accounting for less than 1％ of all salivary gland tumors.

　A 71-year-old woman presented with left parotid swelling；magnetic resonance imaging（MRI）showed a 2-cm left parotid tumor.

　^99mTcO₄⁻ scintigraphy was performed, revealing a high positive rate in the tumor.

　Warthin's tumor was initially suspected, and left partial parotidectomy was subsequently performed.

　Since the tumor was also suspected to be malignant by immediate frozen histological examination, we additionally performed selective neck dissection.

　The tumor was revealed to be an epithelial-myoepithelial carcinoma via permanent histological examination.

　Therefore, epithelial-myoepithelial carcinoma should be considered as a differential diagnosis for ^99mTcO₄⁻ positive parotid tumors.