[Epidemiology, diagnosis, clinical symptoms, and classification of malignant primary skull base tumors]

A review of literature presents up-to-date information on the prevalence, incidence, clinical manifestations, diagnosis, and classification of malignant primary skull base tumors (MPSBTs). In the structure of total cancer incidence, malignant head and neck tumors account for 5% of all annual cancer deaths in the USA and are among the 5 most common groups of tumors in males worldwide. These tumors develop most often in the sixth decade of life, occurring 2 times more often in males than in females. In Russia, the MPSBT incidence (as of 2012) was 0.62% out of all newly diagnosed malignant tumors. The incidence rate amounts to 0.66 per 100 000 population and is significantly higher than the global rate (0.44 per 100 000). About half of all malignant skull base tumors have the epithelial nature and affect the anterior parts of the skull base. The most frequent histological types of malignant skull base tumors are squamous cell carcinoma, adenocarcinoma, and non-Hodgkin's B cell lymphoma. Treatment of skull base tumors is an interdisciplinary problem and the area of interest of otolaryngologists, dentists, ophthalmologists, neurosurgeons, plastic surgeons, radiologists, and chemotherapists. Physical and endoscopic examinations, endoscopic transnasal biopsy, CT, MRI, PET/CT, and ultrasound are typically used for verification of the diagnosis, tumor staging, and selection of the treatment approach. The review describes the criteria for TNM staging of malignant tumors of the nasal cavity and paranasal sinuses in accordance with the 7th version of the TNM recommendations of the American Joint Committee on Cancer (AJCC). The TNM-based staging depends on the location (maxillary sinus, nasal cavity, or ethmoid labyrinth) and histological structure of the tumor, which, in turn, determines the tactics of comprehensive treatment and a prognosis group.