by Jason Wasserman MD PhD FRCPC
March 15, 2023
Non-keratinizing squamous cell carcinoma (NKSCC) is a type of cancer made up of squamous cells. It is described as non-keratinizing because the tumour cells have not undergone a cellular process called keratinization which is commonly seen in normal squamous cells throughout the body. As a result, the squamous cells in NKSCC look less pink and more blue when examined under the microscope.
Common locations for NKSCC include the oropharynx, nasopharynx, sinonasal tract (nasal cavity and paranasal sinuses), lungs, cervix, and anal canal. Less common locations include the oral cavity and larynx. An NKSCC that starts in the nasopharynx is called nasopharyngeal carcinoma.
The cause of NKSCC depends on the location in which the tumour starts. Most tumours in the oropharynx, nasal cavity, paranasal sinuses, cervix, and anal canal are caused by long-standing infection with human papillomavirus (HPV). Similarly, the vast majority of tumours in the nasopharynx are caused by infection with Epstein-Barr virus (EBV). In contrast, most tumours in the lungs are associated with tobacco smoking.
The term metastatic non-keratinizing squamous cell carcinoma is used to describe tumour cells that have spread from the original location of the tumour (this is called the primary tumour) to another part of the body such as a lymph node.
The diagnosis of NKSCC can only be made after tissue is removed and examined under the microscope by a pathologist.
When examined under the microscope, NKSCC is made up of large squamous cells that appear blue when stained with hematoxylin and eosin (H&E). The cells appear blue because the nucleus of the cell (which normally appears blue) is very large while the cytoplasm (body of the cell) contains very little keratin (which normally appears pink). The tumour cells are often arranged in groups which may be described as sheets or nests. Some NKSCCs are made up of individual or small groups of cells surrounded by large numbers of immune cells. This type of NKSCC is called lymphoepithelial carcinoma.