鼻咽部的恶性肿瘤以上皮癌最为多见,但长期以来对其组织学的分类及组织改变的意义存在争论。为此世界卫生组织拟定了三种组织类型:鳞状细胞癌、非角化细胞癌和未分化癌。鳞状细胞癌镜下示有典型的角化和细胞间桥的特征,其各种分化程度可并存,但均需具有上皮样特征。非角化细胞癌分化不良,镜下无鳞状细胞分化的特征。未分化癌为原始细胞(primitive cell)所组成,镜下亦无鳞状细胞分化的特征,细胞有圆或卵圆形的空泡核,核仁显著,瘤细胞间和肿瘤与基质之间的界限不清;瘤细胞排列呈团块状,或其基质与淋巴细胞形成合胞体型(syn- Nasopharyngeal malignancies are more common than epithelial carcinomas, but there has been debate over the histological classification and the significance of tissue changes over a long period of time. To this end, the World Health Organization has developed three tissue types: squamous cell carcinoma, non-keratinocyte carcinoma and undifferentiated carcinoma. Squamous cell carcinoma shows typical features of keratinization and intercellular bridges, and its various degrees of differentiation can coexist, but all need epithelioid characteristics. Non-keratinocyte carcinomas are poorly differentiated and microscopically not characterized by squamous cell differentiation. The undifferentiated carcinoma is composed of primitive cells, and there are no features of squamous cell differentiation under the microscope. The cells have round or oval nucleus vacuoles, prominent nucleoli, between the tumor cells and between the tumor and the stroma. The boundaries are unclear; tumor cells are arranged in clumps, or their stroma and lymphocytes form syncytia (syn-