====== Sinonasal malignant neoplasm ======
Sinonasal malignant neoplasms are rare tumors that constitute about 3% of tumors in the upper respiratory tract. Only a fraction arises at the nasal cavity. 

Due to the contiguity of the nasal cavities with the paranasal sinuses, identifying the specific site of origin of large sinonasal tumors is often difficult. Hence, malignant tumors of the nasal cavities are often grouped with those of the paranasal sinuses. Their proximity to vital structures such as the brain, optic nerves, and internal carotid artery pose significant challenges for their treatment and may be the source of significant morbidity to the patients. Malignant tumors of the sinonasal tract are derived from diverse histologic elements within the nasal cavity. They include the following:
Epithelial

See the list below:

    Squamous cell carcinoma
    Transitional cell carcinoma
    Adenocarcinoma
    Adenoid cystic carcinoma
    Melanoma
    Olfactory neuroblastoma
    Undifferentiated carcinoma

Nonepithelial

See the list below:

    Soft-tissue sarcoma
    Rhabdomyosarcoma
    Leiomyosarcoma
    Fibrosarcoma
    Liposarcoma
    Angiosarcoma
    Myxosarcoma
    Hemangiopericytoma
    Connective tissue sarcoma
    Chondrosarcoma
    Osteosarcoma
    Synovial sarcoma

Lymphoreticular tumors

See the list below:

    Lymphoma
    Plasmacytoma
    Giant cell tumor
    Metastatic carcinoma