What Is The Most Common Parotid Tumor & How Do You Know If You Have It?

Salivary gland tumors are rare and consist of only 3- 5% of all head and neck tumors ^(1). Nearly 80% of all parotid tumors are benign ^(2).

The most common parotid gland tumor is pleomorphic adenoma consisting of around 42% of all the benign tumors of the parotid followed by Warthin’s tumor, while the most common parotid gland malignant tumor is mucoepidermoid carcinoma comprising around 30% ^{(1), (2), (4).}

Pleomorphic adenoma is also known as a benign mixed tumor that is mostly found in females with a female to the male ration of 2:1 and affects individuals of 30-60 years of life. Approximately 80% of pleomorphic adenomas are found in the parotid gland and mostly, about 80-90% of these are found in the superficial part of the parotid gland. The tumor mass has sharp borders and is multilobulated. Although very rare, it also has a chance of transforming into a malignant type known as carcinoma ex pleomorphic adenoma that occurs in 0.15% of the cases ^(2).

Mucoepidermoid carcinoma is the most common malignant tumor of the salivary glands that occurs in 60% of the cases in the parotid gland.

This tumor arises from both the epidermoid and mucus-secreting cells; therefore, it has a cystic component also due to its mucin content.

Clinically, there is a higher chance of misdiagnosis due to its cystic component ^(2).

Parotid gland tumors are mostly found in females, except for Warthin’s tumor. These tumors occur mostly in the fifth decade of life and are mostly found in the Caucasians. Parotid tumor commonly presents itself as a painless mass in about 81% of the cases that are appreciated by accident while washing face or shaving. Pain is seen in only 12% of the cases and facial paralysis in only 7% of the cases of benign tumors. The facial nerve paralysis is mostly seen due to a malignant parotid tumor; however, the most common cause of facial nerve paralysis is Bell’s palsy ^(5.)

On examination, the parotid mass is usually non-tender, solitary, and firm to touch. Malignant tumors are rock-hard to touch with skin fixation, ulceration, and fixation to other structures. Blood and pus may also be appreciated at the opening of the Stensen duct inside the mouth in malignant tumors. It is important to examine the skin, oral cavity, soft palate, tonsillar fossa, and neck for the correct diagnosis and differentiation of benign and malignant mass and further investigation through radiology ^{(4), (5).}

Parotid glands are a pair of salivary glands found in the front and beneath the ears. Along with the submandibular and sublingual glands, they form the major salivary glands. Minor salivary glands consist of around 600-1000 small glands that produce saliva. Parotid glands, in their unstimulated form, produce 10% of the saliva, but when stimulated they produce roughly 25% of the saliva in the mouth. The saliva produced by parotid glands is serious meaning that the saliva is more watery and thin. The parotid gland is made of different kinds of cells due to which it can be afflicted with various tumors and cancers ^(3).

The tumors of salivary glands are rare and account for only 3-5% of all the tumors of the head and neck region out of which only 0.5% are malignant. Parotid glands are the most common site of salivary gland tumors accounting for nearly 60-84.2% of all salivary gland tumors followed by submandibular glands (16%). The tumors of the sublingual glands are very rare but are mostly malignant. Approximately 80% of all parotid gland tumors are benign with the remaining being malignant tumors. As the salivary gland size decreases the propensity for malignancy increases with submandibular glands and sublingual glands consisting of about 50% and 90% malignant tumors, respectively ^{(1), (2).}

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Also Read:

• What are Parotid Tumors or Parotid Mass: Causes, Symptoms, Treatments, Prognosis, Complications