ACC
Adenoid cystic carcinoma (ACC) is an uncommon form of malignant neoplasm that arises within secretory glands, most commonly the major and minor salivary glands of the head and neck. Other sites of origin include the trachea, lacrimal gland, breast, skin, and vulva. It is sometimes referred to as adenocyst, malignant cylindroma, adenocystic, adenoidcystic, ACC, AdCC.
It is the third most common malignant salivary gland tumor overall (after mucoepidermoid carcinoma and polymorphous low grade adenocarcinoma). It represents 28% of malignant submandibular gland tumors, making it the single most common malignant salivary gland tumor.
Symptoms depend on the site of origin of the tumor. In the sinonasal cavity they typically present with nasal obstruction, decreased sense of smell, epistaxis and eye tearing. Late findings can include proptosis. Advanced ACC sinus tumors may present with pain and/or nerve paralysis, for this neoplasm has a propensity to invade peripheral nerves.
The diagnosis is made by histologic analysis of a biopsy or resection specimen of the tumor mass. There are three major variant histologic growth patterns of ACC: cribriform, tubular and solid. The solid pattern is associated with a more aggressive disease course.
Patients typically survive for years with metastases because this tumor is generally well-differentiated and slow growing. Disease specific survival is 89% at 5 years but only 40% at 15 years, reflecting deaths from late-occurring metastatic disease. The lung is by far the most common site of metastasis, with the liver being the second most common site.
Surgical resection, whenever possible, is the mainstay therapy, often followed by radiation therapy. Recurrences are usually identified by radiographic imaging techniques, such as CT
