Symptoms Of Adenoid Cystic Carcinoma

Introduction

Overview of adenoid cystic carcinoma (ACC)

Adenoid cystic carcinoma (ACC) is a rare type of cancer that arises in mucus-producing cells known as glandular cells. It usually originates in salivary glands or other regions of the head and neck. However, it can develop in other parts of the body. ACC is characterised by an abnormal growth of cells that surround glands, known as epithelial cells. Under a microscope, these cells appear to form clusters or cords that invade tubes or gland-like structures in the affected organs. These structures are often filled with mucus or contain abnormal fibrous membranes. ACC is considered a low-grade cancer, which is a term used to describe cancer cells that resemble normal cells under a microscope. Low-grade malignancies tend to grow and spread more slowly than high-grade cancer cells.¹ 

Background of adenoid cystic carcinoma

Definition and rarity of ACC

Adenocarcinoma is an umbrella term describing any form of cancer that begins in the glands; ACC is mostly found in the salivary glands of the head and neck. In rare cases, it can also occur in the brain, breast, lung, uterus, prostate glands in males and other locations in the body. ACC accounts for less than 1 out of every 500 new cases of cancer diagnosed every year.   Even though this cancer can begin at locations other than the salivary gland, ACC is sometimes classified as a disease of the minor salivary gland. ACC is described and classified based on how it appears under a microscope. ACC cells can be classified into:

• Cylindroma: tube-shaped tumour cells
• Cribriform: “swiss cheese” appearance; a tumour with gaps in between the cells
• Solid adenoid cystic carcinoma²

General symptoms of ACC

Initial symptoms of adenoid cystic carcinoma vary from patient to patient and also depend on the size and location of the tumour. Some adenocarcinomas may present as painless masses in the mouth and face. Tumours in the lacrimal gland (glands situated above and on the outer part of the eyelid that secrete tears), may impair vision, whereas those affecting the windpipe and/or voice box may cause respiratory problems or changes in speech respectively.³ 

Head and neck symptoms

Pain or discomfort in the affected area

Adenoid cystic carcinoma can also arise in certain skin regions; If the mass is growing and suppressing nerves, especially in the ear canal, it causes significant pain and discomfort. Masses can also discharge pus and/or blood. These masses appear as reddish nodules (small firm lumps) near the skin surface and can vary in size. Other associated symptoms can include increased sensitivity to stimuli that previously would not be considered as painful.¹

Swelling or lump formation

Symptoms pertaining to ACC can include painless lump formation on the roof of the mouth, the bottom of the mouth or under the tongue. There can be a nodule or lump in front of the ear or underneath the jaw, which can result in pain or discharge pus and/or blood.²

Difficulty swallowing or changes in speech

In some cases, ACC may arise in the mucus-producing glands within the voice box (larynx). The larynx is between the throat and the windpipe (trachea). Tumour growth between the vocal cords may lead to persistent hoarseness, sore throat, changes in speech and difficulty swallowing. Some individuals who have ACC of the larynx may notice a mass in the neck area which may cause pain and discomfort. Difficulty swallowing food may also be due to ACC developing in the oesophagus (the tube that connects your mouth to your stomach), however, this is extremely rare. As the tumour grows, ACC patients may find swallowing soft foods, liquids and even saliva to be difficult. This often results in frequent regurgitation of food and subsequent weight loss.

Respiratory symptoms

Persistent coughing or wheezing

With tracheal ACC the most frequent symptoms observed in patients are coughing and wheezing. Hemoptysis, coughing up blood, can also occur.⁵

Shortness of breath or difficulty breathing

If the mucus-producing glands within the trachea develop cancerous ACC, the trachea will become obstructed and cause shortness of breath (dyspnea), laboured (uneven) breathing and abnormal breathing sounds whilst inhaling.⁴

Ocular symptoms

Changes in vision or double vision

The lacrimal gland in our eye produces tears. Tumours in the lacrimal sac are quite rare, and they typically obstruct the lacrimal drainage system. If there is a cancerous mass developing in this region, it can lead to changes in vision.

Eye pain or discomfort

Persistent pain, skin ulceration, and double vision that is not responding to general treatment are all highly suspicious of malignancy, as discussed in this case report.

Protrusion or swelling of the eye

Another symptom of lacrimal ACC is proptosis- bulging of the eye. This can be misdiagnosed as dacryocystitis (infection of the lacrimal sac) unless further imaging tests are done to rule out a lacrimal tumour.⁶ 

Salivary gland symptoms

Dry mouth or changes in taste

Dryness of mouth, also known as xerostomia, can sometimes be associated with ACC, though it is important to note that this is not exclusive to this condition. ACC 

affects the normal function of the salivary glands, and may result in reduced saliva production leading to a dry mouth. This can cause discomfort, and difficulty speaking and swallowing.

Dysguesia, changes in taste, can occur due to the cancer affecting the nerve endings of taste buds. Advanced adenoid cystic carcinoma is treated with surgical resection and radiotherapy combined. One study showed that postoperative radiotherapy for head and neck tumours may result in changes in taste and dry mouth.⁷ 

Swelling or lumps in the salivary glands

ACC of the salivary gland can result in the formation of painless lumps in the mouth, face or neck. Lumps can also form on the roof of the mouth and under the tongue.

Neurological symptoms

Facial numbness or weakness

Adenoid cystic carcinoma of the salivary glands can present as numbness of the upper jaw, palate (roof of the mouth), face or tongue. There can also be nerve impairment which causes certain facial muscles to weaken and/or create other facial abnormalities.² 

Difficulty with facial movements

If tumour cells travel along large nerves before they are diagnosed, they can cause nerve dysfunction, such as facial weakness, numbness or tingling, and difficulty with facial expressions.

Headaches or seizures (rare)

Systemic symptoms

Fatigue or weakness

Amongst the respiratory symptoms of ACC, if the cancer spreads to the lower respiratory tract, an individual could experience malaise, feelings of ill health and weakness.

Unexplained weight Loss

As ACC metastasises (spread of cancer)  to the oesophagus and the respiratory tract, patients can find swallowing food to be extremely difficult. This may also lead to frequent vomiting resulting in weight loss, and fatigue.¹

Summary

Adenoid cystic carcinoma is a rare malignant tumour of the epithelial cells lining the salivary gland. It is slow growing (indolent), and has a high rate of distant metastasis, meaning that the tumour is more likely to spread to distant organs from wherever it originates. It also has a high rate of recurrence, so close follow-up after treatment is extremely necessary. ACC can manifest in pain or painless lumps and swellings around the mouth and in the salivary glands, parotid (salivary glands in front of the ears) glands, lacrimal glands, mucosal glands of the trachea, and elsewhere. Due to its slow yet unpredictable growth, it can metastasise to distant organs such as the cervix in females and the prostate in males. As ACC spreads via perineural invasion, tumours suppressing nerves can cause damage to the facial muscles and ACC patients may experience facial numbness and weakness along with pain and increased sensitivity.