Cellular Classification of Nasopharyngeal Cancer
Although a wide variety of malignant tumors may arise in the nasopharynx, only squamous cell carcinoma is considered in this discussion because management of the other types varies substantially with histology. Subdivisions of squamous cell carcinoma in this site include the following:
World Health Organization (WHO) histopathological grading system describes three types of nasopharyngeal cancer:
- Keratinizing squamous cell carcinoma.
- Nonkeratinizing squamous cell carcinoma.
- Undifferentiated carcinoma (most common subtype).
Previous subdivisions of nasopharyngeal carcinoma included lymphoepithelioma, which is now classified as WHO grade III characterized by lymphoid infiltrate.
WHO grade I-type cancer accounts for 20% of cases in United States and is associated with alcohol and tobacco use; WHO grade II and III represent the endemic form seen in Southern China.
The presence of keratin has been associated with reduced local control and survival.References
- Shanmugaratnam K, Sobin L: Histological Typing of Upper Respiratory Tract Tumours. Geneva: World Health Organization, 1978. International Histologic Classification of Tumours: No. 19.