Nasopharyngeal carcinoma most commonly occurs in the roof of the nasopharynx, followed by the lateral walls and pharyngeal recesses, and it can occasionally be multiple.
Visual inspection
Nasopharyngeal carcinoma can present in four distinct forms: nodular, cauliflower-like, infiltrative, and ulcerative, with the nodular type being the most common, followed by the cauliflower-like form. In the early stages, the local mucosa may appear rough and slightly elevated. In contrast, the infiltrative type often maintains intact mucosal surfaces, as cancerous tissue grows aggressively beneath the mucosa—so much so that cervical lymph node metastasis may already have occurred before the primary tumor is even detected.
Histological type
Nasopharyngeal carcinoma predominantly originates from the reserve cells of the columnar epithelium lining the nasopharynx—these reserve cells are primitive, multipotent cells capable of differentiating into either columnar or squamous epithelial tissue.
The commonly used histological types of nasopharyngeal carcinoma are as follows:
1. In well-differentiated squamous cell carcinoma, the cancer cell nests exhibit distinct layering, and numerous keratin pearls are visible. In contrast, poorly differentiated squamous cell carcinoma typically lacks keratinization; instead, cancer cells form irregularly shaped nests of varying sizes, with no clear cellular layering. The cancer cells appear polygonal or oval, featuring abundant cytoplasm and well-defined borders, though a few cells may still show intercellular bridges. Poorly differentiated squamous cell carcinoma is more commonly observed.
2. Adenocarcinomas typically arise from the columnar epithelium of mucous membranes. Highly differentiated adenocarcinomas are extremely rare, with cancer cells arranged in alveolar or gland-like structures. In contrast, poorly differentiated adenocarcinomas feature cancer cells organized into irregular cords or sheets, occasionally showing gland-like structures or a tendency to form actual glandular lumens.
3. Undifferentiated carcinoma primarily has two subtypes. The first type is known as clear-cell carcinoma or large round-cell carcinoma, formerly referred to as lymphoepithelial carcinoma. Tumor nests vary in size and exhibit irregular shapes, with poorly defined borders against the surrounding stroma. The cancer cells are relatively large, with abundant cytoplasm and indistinct cell boundaries. Their nuclei are large, deeply vacuolated, and typically round or oval in shape, featuring well-defined nuclear membranes and visible 1–2 prominent nucleoli. Lymphocytic infiltration is commonly observed between the cancer cells. The second subtype is characterized by smaller cancer cells that contain minimal cytoplasm and display a round or short spindle-like morphology. These cells are diffusely distributed throughout the tissue, without forming distinct tumor nests. This subtype tends to be more aggressive.
Modes of spread
1. Direct extension of the tumor can invade and destroy the bones of the skull base as it spreads upward, with destruction at the foramen ovale being the most common finding. In advanced stages, the tumor may erode the sella turcica and, through the破裂 foramen, affect cranial nerves II to VI, leading to corresponding clinical symptoms. When spreading downward, the tumor can infiltrate the oropharynx, palatine tonsils, and base of the tongue; moving forward, it may invade the nasal cavity and orbit; and extending backward, it can affect the cervical spine. Additionally, the tumor may spread laterally into the Eustachian tube, reaching the middle ear.
2. Lymphatic metastasis: The nasopharyngeal mucosa's lamina propria is rich in lymphatic vessels, allowing early lymphatic spread of this cancer. In fact, more than half of nasopharyngeal carcinoma patients initially present with enlarged cervical lymph nodes. Metastasis typically begins in the retropharyngeal lymph nodes and then spreads to the deep upper cervical and other regional lymph nodes, rarely affecting the superficial cervical lymph nodes. Notably, cervical lymph node involvement usually occurs on the same side, followed by bilateral involvement, while metastasis to the contralateral side is extremely uncommon.
3. Hematogenous metastasis commonly spreads to the liver, lungs, and bones, followed by sites such as the kidneys, adrenal glands, and pancreas.
According to China's unified classification, nasopharyngeal carcinoma is histologically categorized into undifferentiated carcinoma, well-differentiated carcinoma (including large round cell carcinoma, pleomorphic carcinoma, spindle cell carcinoma, and mixed cell carcinoma), and moderately differentiated carcinoma (such as squamous cell carcinoma grades I and II, as well as adenocarcinoma). In contrast, the World Health Organization classifies it into keratinizing squamous cell carcinoma, non-keratinizing squamous cell carcinoma, and undifferentiated carcinoma. For more information, please contact the Taixinsheng hotline at 010-51571020.