Nagao Toshitaka, Gaffey Thomas A, Kay Paul A, Unni Krishnan K, Nascimento Antonio G, Sebo Thomas J, Serizawa Hiromi, Minato Hiroshi, Lewis Jean E
Division of Anatomic Pathology, Mayo Clinic, Rochester, MN 55905, USA.
Hum Pathol. 2003 Oct;34(10):1068-72. doi: 10.1053/s0046-8177(03)00418-0.
Mucoepidermoid carcinoma (MEC), a common malignant salivary gland neoplasm, is generally divided into low-, intermediate-, and high-grade types according to the histologic features. To our knowledge, the present report describes the first case of dedifferentiation occurring in a low-grade MEC. A 55-year-old man presented with a biphasic neoplasm of the right parotid gland composed of low-grade MEC and dedifferentiated high-grade anaplastic undifferentiated carcinoma. Immunohistochemically, carcinoembryonic antigen expression was restricted to the low-grade MEC portion. The Ki-67-labeling index was higher in the dedifferentiated component than in the low-grade component. On image cytometric analysis, the low-grade MEC was diploid, whereas the dedifferentiated carcinoma was aneuploid. Although the patient was alive 10 years after the initial diagnosis, the tumor has recurred twice, at 3 months and 7 months after the initial resection. It is important to recognize that dedifferentiation can occur in a low-grade MEC, similar to other low-grade salivary gland carcinomas.
黏液表皮样癌（MEC）是一种常见的涎腺恶性肿瘤，通常根据组织学特征分为低级别、中级别和高级别类型。据我们所知，本报告描述了首例发生在低级别MEC中的去分化病例。一名55岁男性患者，右腮腺出现一种双相性肿瘤，由低级别MEC和去分化的高级别间变性未分化癌组成。免疫组化显示，癌胚抗原表达仅限于低级别MEC部分。去分化成分的Ki-67标记指数高于低级别成分。图像细胞分析显示，低级别MEC为二倍体，而去分化癌为非整倍体。尽管患者在初次诊断后10年仍存活，但肿瘤已复发两次，分别在初次切除后3个月和7个月。认识到低级别MEC中可发生去分化很重要，这与其他低级别涎腺癌类似。
