The histopathological spectrum of nasopharyngeal carcinoma.

Nonglandular carcinomas of the nasopharynx originate in the epithelium of that anatomical region. Although numerous morphological patterns exist at the level observable by light microscopy, ultrastructurally, all have features of squamous-cell carcinoma. The most useful and consistent classification on the basis of light microscopy is that which separates keratinizing squamous carcinomas from nonkeratinizing carcinomas. Approximately 25% of tumours have abundant and easily recognized keratin. The nonkeratinizing types are more confusing, since many variants exist, both from tumour to tumour and, frequently, within the same tumour. Variable tissue reactions to infiltrating tumours, ranging from marked desmoplasia to complete absence of reaction, add to the confusion. The descriptive names applied to the variants of nonkeratinizing squamous carcinomas are well engraved in medical communications, and there is little chance that they will be abandoned.