Adenoid cystic carcinoma (ACC) is a rare form of adenocarcinoma, a type of cancer that begins in glandular tissues. It most commonly arises in the major and minor salivary glands of the head and neck. It can also occur in the breast, uterus, or other locations in the body. Symptoms depend on the tumor's location. Salivary gland tumors may cause painless masses in the mouth or face. Tumors of the lacrimal gland may cause a bulging eye or changes in vision. Those affecting the windpipe or voice box may cause respiratory symptoms or changes in speech, respectively. Advanced tumors may cause pain and/or nerve paralysis, as ACC often spreads along the nerves. It may also spread through the bloodstream. It spreads to the lymph nodes in about 5% to 10% of cases. The cause of ACC is currently unknown. It typically does not run in families.