Adenoid cystic carcinoma (ACC) is a relatively rare form of cancer that most commonly develops in the salivary glands or other regions of the head and neck. In some cases, ACC may arise in other primary sites, such as the skin; the breast; the neck of the uterus (cervix) in females, the prostate gland in males; or other areas.
The term "cancer" refers to a group of diseases characterized by abnormal, uncontrolled cellular growth that invades surrounding tissues and may spread (metastasize) to distant bodily tissues or organs via the bloodstream, the lymphatic system, or other means. Different forms of cancer, including adenoid cystic carcinoma, may be classified based upon the cell type involved, the specific nature of the malignancy, the tissues or organs affected, and the disease's clinical course.
ACC tumors are characterized by a distinctive pattern in which abnormal "nests" or cords of certain cells (epithelial cells) surround and/or infiltrate ducts or glandular structures within the affected organ. These structures are typically filled with a mucous-like material or contain abnormal fibrous membranes (hyaline membranes). Such characteristics are apparent during microscopic evaluation of the tumor cells. ACC is considered a low-grade malignancy that has a history of slow growth, but tends to be aggressively invasive and to infiltrate nearby lymph nodes as well as the "sheaths" or coatings surrounding nerve fibers (perineural spaces). This form of cancer may have a tendency to recur later at the site where it first developed (local recurrence) and to spread to distant bodily sites, particularly the lungs, potentially resulting in life-threatening complications.