There are three histological tumor growth patterns common to ACC: cribriform, tubular, and solid. The cribriform growth pattern is most common and appears as a “Swiss cheese” pattern in histological stains. The cribriform and tubular growth patterns are less aggressive. Tumors exhibiting a solid pattern are more likely to spread and have a worse prognosis.
ACC most commonly arises in the salivary glands or other areas within the head and neck region. Symptoms of ACC of the salivary glands may include numbness of the lower lip and/or other facial areas; nerve impairment causing Weakness of certain facial muscles; ongoing pain; and/or other associated abnormalities. The specific symptoms observed vary between patients and depends on both the size of the tumor and specific salivary gland and nerve(s) affected by the malignancy.
The lacrimal gland is the gland that produces tears. Symptoms of lacrimal gland ACC include a bulging eye (proptosis) or changes in vision. Although lacrimal gland ACC appears to occur predominantly during adulthood, there have been some reports of the disease in children and adolescents. Some researchers indicate that this form of ACC assumes a somewhat less aggressive course when it occurs among the young.
ACC may also arise in certain skin regions (primary cutaneous ACC). Such malignancies primarily develop on the scalp and external ear canal, potentially resulting in pain, discharge of pus and/or blood, and/or other symptoms. The development of isolated or multiple reddish (erythematous) nodules or plaques that vary in size typically characterize ACC of the skin. ACC of the skin is due to abnormal cell growth and tends to invade local soft tissue and bone aggressively. Other primary sites of tumor development include the arms or legs, and trunk. Although associated symptoms may vary, findings may include pain, increased sensitivity, or perceiving Pain from stimuli not normally associated with pain. In addition, individuals with involvement of the scalp may experience hair loss in the area of tumor growth. ACC of the skin can be aggressive and may be associated with infiltration of nerves and, in rare cases, result in distant metastases. In addition, many affected individuals have local recurrences may develop months or years after surgical removal of the initial lesion.
ACC may also arise within certain organs of the lower or upper respiratory tract, breast, esophagus, cervix (females), and prostate gland (males). Descriptions of these forms of ACC are provided in the following paragraphs.
ACC of the lower respiratory tract most frequently develops in mucous glands of the trachea, particularly the upper third. In individuals with tracheal ACC, tumor growth gradually causes obstruction of the windpipe, resulting in difficult or labored breathing; hoarseness; and/or a high-pitched, respiratory sound upon the intake of breath (stridor). Additional symptoms may include a general feeling of ill health (malaise), weight loss, pain, recurrent inflammation of the lungs (pneumonitis), and/or the coughing up of blood.
In ACC of the lower respiratory tract, the malignancy tends to infiltrate regional lymph nodes and may spread along nerves to bone, particularly the spine (vertebrae). More rarely, sites of metastases may include the lungs, liver, brain, kidneys, or other regions.
In some individuals, ACC may also arise in mucous glands of the voice box (larynx), which lies between the throat and the trachea. ACC of the larynx most commonly arises in the region beneath the glottis, which is the slit-like opening between the vocal cords. In addition, these tumors may regionally invade the vocal cords. Tumor growth in the subglottic region gradually results in difficulty breathing upon exertion, shortness of breath, and eventual airway obstruction. When the malignancy develops above the opening; between the vocal cords, it may eventually result in persistent hoarseness, change in speech, difficulty swallowing, and soreness of the throat. In some individuals with ACC of the larynx, a mass may be seen in the neck area. Because this malignancy tends to infiltrate nerves, some affected individuals may also experience associated Pain or discomfort. Laryngeal ACC may spread through the bloodstream, as well as via the nerves. Metastatic disease most typically occurs in the lungs; however, other sites may include bone or the brain.
ACC of the esophagus, which is extremely rare, has the same cellular structure and composition as ACC of the salivary glands and other areas of the body. As with ACC of the salivary gland, esophageal ACC is a slow-growing malignancy that may be prone to perineural invasion, local recurrences, and distant metastases. Initially, affected individuals may have problems swallowing solids. With increasing tumor growth, they may have difficulties swallowing soft foods as well as liquids, including even saliva in some cases. This typically results in regurgitation of food and liquids, with associated weight loss.
ACC may also arise in the breast. However, the disease course may be markedly different from primary ACC in other regions of the body. For example, ACC of the breast is considered a less aggressive malignancy that is not as likely to invade regional lymph nodes, metastasize, or locally recur. Compared to other forms of breast cancer, ACC is low-grade and progresses slowly. Researchers attribute such characteristics to several possible factors, such as slower overall tumor growth, relatively small tumor size, and an increased ability to remove all traces of such malignancies surgically. However, this malignancy tends to invade adjacent tissue and infiltrate nerves. In addition, although considered extremely rare, local recurrences may develop and metastatic disease may occur months or years after surgical removal of the primary tumor. The most common site of metastatic disease is the lung. Other, more rarely reported areas of metastasis include lymph nodes, soft tissue, bone, brain, and kidneys. Incomplete removal of the primary tumor contributes to rare cases of local recurrence and metastasis. Less than 0.1% of all breast carcinomas are diagnosed as ACC.
According to reports in the medical literature, only one breast is affected. To date, no cases have been reported in which both breasts developed ACC. ACC of the breast is characterized by the excessive growth of two specific cell types (luminal and basaloid) in specific patterns.
Patients develop a slowly enlarging, moveable mass that may cause Tenderness or pain, unlike some other forms of breast cancer. Tumors tend to develop in the region of the nipple or areola (the pigmented, circular area of skin surrounding the nipple). Findings associated with other malignancies in this region include bloody discharge, indentation of the nipple, and/or tumor invasion of the chest muscle, appear to be uncommon in association with ACC.
In females, ACC may also arise in the cervix, particularly after menopause. Initial symptoms include a watery or bloodstained discharge or vaginal bleeding in association with a relatively large cervical mass. ACC of the cervix frequently recurs locally, spreads to lymph nodes/vessels and perineural spaces, and metastasizes to distant organs. ACC accounts for 0.1% of all cervical cancer cases and is very aggressive.
In males, ACC may arise in the prostate gland. This rare form of ACC is considered a subtype of prostate adenocarcinoma, a common form of prostate cancer. Symptoms may include poor flow of urine, increased frequency of urination, and/or difficulties beginning urination due to enlargement of the prostate gland and associated obstruction of the urinary tract.
Rarely, ACC may arise in other regions of the body. The specific symptoms and clinical course may vary from person to person, depending upon the primary tumor site, size, nature, progression, and other factors.