1999 Volume 38 Issue 4 Pages 323-327
Background: Epithelial-myoepithelial carcinoma of the parotid gland is a rare tumor that is mostly observed in females in their sixties, and is recognized as a low malignant tumor.
Case: The patient was a 60-year-old male, who noticed swelling of the parotid gland and underwent examinations in our hospital. Malignant tumor was suspected on cytodiagnosis of needle biopsy specimen. On needle biopsy, large and small cells were observed against backgrounds of hyaline component and pronucleus-like cells. Cells formed slightly sparse cell clusters. The cytoplasm was stained bright green and the nuclei were round or nearly round with small granular chromatin. The nucleli were clear. The small cells had small cytoplasm and formed dense cell clusters, partially showing a lumen-like structure. The nuclei were nearly round or round with granular chromatin and the nucleoli were clear. The large and small cells were more clearly distinguished by Giemsa stain than Papanicolau stain.
On histological examination, the tumor cells were divided by the hyalinized interstitium, which had a bilaminar structure. On immunohistochemical investigation, the former cells were positive for EMA and keratin and the latter cells were positive fora-SMA and S-100 protein.
Conclusion: On preoperative cytodiagnosis, monomorphic adenoma or adenocarcinoma was suspected, since the large and small cells were the same type and the case was reported as false positive. It may be possible to judge a tumor by cytodiagnosis, considering the cytological characteristics of this tumor.
