Mucoepidermoid Carcinoma

Mucoepidermoid Carcinoma

The salivary glands are those glands whose primary function is to produce saliva. Cancer in the salivary gland is called salivary gland cancer. There are two types of salivary glands: major salivary glands comprising of three pairs of glands (parotid, submandibular, and sublingual glands) around mouth and throat and minor salivary glands, hundreds of which are found throughout the palate, nasal and oral cavity. Tumors in these glands may be benign or malignant. Most of these tumors develop in the parotid gland while others involve the submandibular glands and the minor salivary glands. Among the malignant types, mucoepidermoid carcinoma is the most common primary carcinoma of major and minor salivary glands, accounting for 5% to 10% of all salivary gland tumors and 30 % of all salivary carcinomas.

Other malignant lesions include adenocarcinoma, squamous cell carcinoma, malignant degeneration of a pleomorphic adenoma, and adenoid cystic carcinoma. Most (70%) salivary gland tumors originate in the parotid gland. The remaining tumors arise in the submandibular gland (10% to 20%), sublingual salivary glands and minor salivary glands.

Epidemiology

Mucoepidermoid carcinoma is the most common primary carcinoma of major and minor salivary glands, accounting for about one-third of all salivary carcinomas.

The epidemiology is not well documented and varies based upon geography and populations studied. The disease mainly occurs in people above 55 years of age. It is a rare cancer. All the salivary gland cancers together are less than 1% of cancers in the United States.

Signs and symptoms of mucoepidermoid carcinoma of parotid gland

At the initial stage, a painless slow growing mass appears. As the disease progresses in case of malignant tumors, the symptoms that may be observed are:

  • Tenderness
  • Ear pain, or pain in the neck or mouth
  • Pain or trouble with swallowing
  • Difficulty opening the mouth
  • Bleeding
  • Facial paralysis, numbness, paresthesia, or a loss of motor function.

Grading

Mucoepidermoid carcinomas are graded as using the types of cells visible. The grade depends on whether or not the tumor is more cystic or solid, and how abnormal the cells appear. The carcinomas are called:

  • Low grade
  • Intermediate grade
  • High grade

Risk factors or causes

Alcohol consumption and smoking are not associated with increased risk for developing salivary gland neoplasms. The main risk factor is previous radiation exposure.

Molecular biology

There is a chromosomal abnormality associated in mucoepidermoid carcinomas.

Cytological features and Differential diagnosis

Diagnosis by imaging

Ultra sound: This procedure with sound waves gives an image of the internal parts on a computer screen. This technique is used to detect lumps and swellings in salivary glands.

CT: The CT scan is a procedure by which images of the internal organs of the body can be obtained with a help of x-rays. A contrasting dye is injected in the veins so that the images are clearly understood. The images can be viewed with the help of a computer.

Magnetic resonance imaging (MRI): This imaging procedure is based on the use of radiowaves in the presence of a magnet. The images produced can be viewed with the help of a computer attached to the machine.

Biopsy: A biopsy must be done to diagnose and characterize the tumor. This can be a needle biopsy or examination of the tumor that has been removed. A pathologist will look at the tumor to see how aggressive it appears.

Staging:  This is based on how far the tumor has progressed.

Treatment

Treatment is planned based on stage of disease, tumor grade and location. Mostly surgery is performed to treat mucoepidermoid carcinomas. Radiation therapy can be used sometimes according to the condition of the tumor. Chemotherapy is used rarely.

Treatment for stage I and II mucoepidermoid carcinoma:

Surgical excision alone—parotidectomy (removal of parotid gland) without damaging facial nerve, removal of submandibular gland or wide local excision of affected minor salivary glands.

Treatment for stage III and IV mucoepidermoid carcinomas:

Radical excision and neck dissection or postoperative radiation therapy is the likely treatment. Facial nerve should be preserved in all these operations, but may be sacrificed only when tumor is directly involved with the nerve.

Postoperative irradiation of major salivary gland tumors is indicated in cases of tumors that are larger than 3 cm or are high-grade, or if they include facial nerve invasion, involved margins, perineural or perilymphatic extension, or evidence of lymph node involvement.

Prognosis

Prognosis depends on many factors including clinical stage and histological grade of mucoepidermoid carcinoma. The 5-year survival rate for the low-grade mucoepidermoid carcinoma is 92–100 % indicating that prognosis is good if the disease is diagnosed early. However, for high-grade mucoepidermoid carcinoma the 5-year survival rate decreases to 0–43%.

References

  1. Ryan JT, El-Naggar AK, Huh W, Hanna EY, Weber RS, Kupferman ME. (2011) Primacy of surgery in the management of mucoepidermoid carcinoma in children. Head Neck. Jan 31. doi: 10.1002/hed.21675.
  2. Chenevert J, Barnes LE, Chiosea SI. (2011) Mucoepidermoid carcinoma: a five-decade journey. Virchows Arch.;458(2):133-40.
  3. Miguens SA Jr, Uchoa Vasconcelos AC, Figueiredo MA, Soares Yurgel L, Salum F, Cherubini K. (2010) Mucoepidermoid carcinoma: a retrospective study.Minerva Stomatol.;59(6):325-32.
  4. Verma J, Teh BS, Paulino AC. (2011) Characteristics and outcome of radiation and chemotherapy-related mucoepidermoid carcinoma of the salivary glands. Pediatr Blood Cancer. 2011 Jan 28. doi: 10.1002/pbc.22978.
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.