Question: What is (are) Adenoid cystic carcinoma ?
Answer: Adenoid cystic carcinoma (ACC) is a rare form of adenocarcinoma, which is cancer that begins in gladular tissues. ACC most commonly arises in the head and neck, in various parts of the major and minor salivary glands including the palate, nasopharynx, lining of the mouth, voice box (larynx) or windpipe (trachea). It can also occur in the breast, uterus, or other locations in the body. Early symptoms depend on the tumor's location and may include lumps under the lining of the mouth or facial skin; numbness in the mouth or face; difficulty swallowing; hoarseness; pain; or paralysis of a facial nerve. ACC often has long periods with no growth followed by growth spurts; however, it can be aggressive in some people. ACC spreads along nerves or through the bloodstream, and only spreads to the lymph nodes in about 5-10% of cases. The cause of ACC is currently unknown. Treatment depends on many factors and may include surgery, radiation, and/or chemotherapy.
Source: GARD

Question: What causes Adenoid cystic carcinoma ?
Answer: What causes adenoid cystic carcinoma? The underlying cause of adenoid cystic carcinoma (ACC) is not yet known, and no strong genetic or environmental risk factors specific to ACC have been identified. Researchers believe that a combination of various genetic and environmental factors probably interact to ultimately cause a person to develop specific types of cancers. There is ongoing research to learn more about the many factors that contribute to the development of cancer. Cancer is at least partly due to acquired (not inherited) damage or changes to the DNA in certain cells. For example, various studies have shown that chromosomal abnormalities and genetic deletions are present in samples of ACC. However, these genetic abnormalities are present only in the cancer cells, not in the cells with the genetic material that is passed on to offspring (the egg and sperm cells).
Source: GARD