Department of Pathology, Shizuoka General Hospital, 4-27-1 Kita-ando, Aoi-ku, Shizuoka, 420-8527, Japan.
Department of Head and Neck Surgery and Otorhinolaryngology, Shizuoka General Hospital, Shizuoka, Japan.
Med Mol Morphol. 2021 Jun;54(2):173-180. doi: 10.1007/s00795-020-00262-6. Epub 2020 Aug 4.
Epithelial-myoepithelial carcinoma (EMCa) is a rare low-grade salivary malignancy. It is rare for EMCa to occur as the carcinomatous component of carcinoma ex-pleomorphic adenoma (PA). We examined one additional case of EMCa ex-PA, immunohistochemically and genetically. The patient was an 83-year-old female, who suffered from swelling of the right parotid region. Histologically, the tumor contained a hyalinized nodule, which displayed elastosis. The main tumor exhibited a bi-layered structure, involving inner ductal cells and clear outer myoepithelial cells. Immunostaining indicated that the inner cells were positive for epithelial membrane antigen, whereas the outer cells were positive for p40. On the genetic level, the carcinoma harbored no HRAS gene mutations, whereas fluorescence in situ hybridization (FISH) of the Pleomorphic Adenoma Gene1 showed splitting signals in the carcinomatous component. We diagnosed this case as EMCa ex-PA. It is necessary to differentiate EMCa ex-PA from myoepithelial carcinoma and clear cell carcinoma, and FISH is useful for such purposes.
上皮-肌上皮癌（EMCa）是一种罕见的低级别涎腺恶性肿瘤。EMCa 作为多形性腺瘤（PA）的癌性成分很少见。我们通过免疫组织化学和遗传学检查了另外一例 EMCa 伴发 PA。患者为 83 岁女性，右腮腺区肿胀。组织学上，肿瘤含有玻璃样结节，伴有弹性组织变性。主要肿瘤呈双层结构，包括内层导管细胞和清晰的外层肌上皮细胞。免疫组化染色显示内层细胞上皮膜抗原阳性，而外层细胞 p40 阳性。在基因水平上，癌组织没有 HRAS 基因突变，而多形性腺瘤基因 1 的荧光原位杂交（FISH）显示癌性成分存在分裂信号。我们诊断该病例为 EMCa 伴发 PA。有必要将 EMCa 伴发 PA 与肌上皮癌和透明细胞癌相鉴别，FISH 对此很有用。
