Sinonasal undifferentiated carcinoma (SNUC) is a type of cancer that develops in the sinuses of the head. SNUC occurs when cells from the layer of tissue that lines the sinuses (called the epithelium) rapidly increase in number, forming a mass. The first symptoms of SNUC may include difficulty breathing though the nose or mild facial pain. As SNUC progresses, other symptoms may include nosebleeds, facial numbness, or tingling in the face. SNUC is an aggressive cancer, meaning it grows rapidly and has a tendency to spread into healthy tissues nearby and to more distant parts of the body (metastasis).

The cause of SNUC is still unknown. When possible, the treatment is the complete removal of the tumor, combined with radiation therapy and chemotherapy. In cases where the tumor can't be removed completely, the treatment is with radiation and chemotherapy. The risk of the tumor coming back (relapse) is high and the probability of cure is modest.

The exact cause of this tumor is still unknown. There are several risk factors that may increase the chances of developing it, such as:

• Occupational exposure: Breathing in certain substances while working, such as dust from the manufacturing of wood, textiles, leather, flour, and metals (including nickel and chromium).
• Being infected with human papillomavirus (HPV).
• Being male and older than 40 years.
• Smoking.