同側耳下腺内における多形腺腫と筋上皮腫の発生例

抄録

In many cases, synchronous parotid gland tumors are multiple occurrences of Warthin’s tumors, and occurrence of histologically different tumors in the same parotid gland is rare. We report a case of synchronous occurrence of a pleomorphic adenoma and myoepithelioma in the same parotid gland.

A 74-year-old man presented with two masses in the left parotid gland. On magnetic resonance imaging, the inferior tumor was visualized on T2-weighted images as a mixture of high signal intensity and low signal intensity; on the other hand, the superior tumor showed high signal intensity in the peripheral region and uniform low signal intensity in the central region. Therefore we considered the two tumors as being of different histological types. The tumors were resected by superficial parotidectomy. The histopathological diagnosis of the inferior tumor was pleomorphic adenoma, while that of the superior tumor was myoepithelioma. Until now, two years since the surgery, there has been no recurrence of either type of tumor in the parotid gland.

In patients with multiple parotid gland tumors, diagnosis of the tissue types of the tumors prior to the operation is important, because it has an influence on the prognosis of the patients.