耳下腺に発生した基底細胞腺腫

Basal cell adenoma in the parotid gland：case report

はじめに

　基底細胞腺腫は唾液腺，特に耳下腺に好発する良性腫瘍である。耳下腺における基底細胞腺腫の発生頻度は多形腺腫，ワルチン腫瘍に次いで3番目に高いが，耳下腺腫瘍に占める割合は約3％であり，比較的稀な腫瘍といえる^1）。今回われわれは，病理組織学診断では基底細胞腺腫が第一に疑われたが，多形腺腫との鑑別が必要であり，確定診断に免疫組織学的検索が有用であった耳下腺基底細胞腺腫例を経験したので若干の考察を加え，報告する。

　A 44-year-old man presented with an elastic soft mass in his right neck. Ultrasound and MRI indicated a benign parotid gland tumor. Deep lobectomy of parotid gland was performed. Histopathological examination suggested that the tumor was basal cell adenoma. Immunohistochemical examination was used to distinguish the tumor from pleomorphic adenoma. Tumor cells were negative for GFAP. The inner cells of the tubular components were positive for Cytokeratin CAM5.2 and the outer cells were positive for αSMA. Immunohistochemistry confirmed the diagnosis.