Histological classification of nasopharyngeal carcinoma

Clinically, nasopharyngeal carcinoma can be observed with the naked eye in four forms: nodular, cauliflower, invasive and ulcerative. However, the histological classification of nasopharyngeal carcinoma is not so intuitive. The vast majority of nasopharyngeal carcinomas originate from the reserve cells of the columnar epithelium of the nasopharyngeal mucosa. The reserve cells are primitive multipotent cells that can differentiate into columnar epithelium or squamous epithelium.

1. Adenocarcinoma

Most of them come from the columnar epithelium of the mucosa. Well-differentiated adenocarcinoma is extremely rare, and the cancer cells are arranged in alveolar or glandular cavity-like structures. Poorly differentiated adenocarcinoma cancer cells are arranged in irregular cords or sheets, occasionally with glandular cavity-like structures or a tendency to form glandular cavities.

2. Squamous cell carcinoma

In well-differentiated squamous cell carcinoma, the cancer nests are clearly stratified, and a large number of keratinized beads can be seen. In poorly differentiated squamous cell carcinoma, there is often no keratinization, and the cancer cells form cancer nests of varying sizes and irregular shapes, with no obvious stratification of cancer cells. The cancer cells are polygonal or oval, with abundant cytoplasm and clear boundaries. In a few cancer cells, intercellular bridges can be seen. Poorly differentiated squamous cell carcinoma is common.

3. Undifferentiated carcinoma

There are two main subtypes. One is called vesicular nuclear cell carcinoma or large round cell carcinoma, formerly known as lymphoepithelial carcinoma. The cancer nests vary in size and shape, and the boundary with the stroma is not very clear. The cancer cells are large in size, with rich cytoplasm, unclear cell boundaries, large vacuolated nuclei, round or oval nuclei, clear nuclear membranes, and 1 to 2 large nucleoli. Lymphocyte infiltration is common among cancer cells. The other type is characterized by smaller cancer cells, less cytoplasm, and round or short spindle shapes. Cancer cells are diffusely distributed, and there is no obvious cancer nest formation. It is highly malignant.