mucoepidermoid carcinoma – most common malignant salivary gland tumor

After reading this post you will learn the following about Mucoepidermoid Carcinoma

• INTRODUCTION
• CLINICAL FEATURES
• HISTOPATHOLOGIC FEATURES
• VARIANTS OF TUMOR
• TREATMENT & PROGNOIS

INTRODUCTION

• MUCOEPIDERMOID CARCINOMA – As the name implies
  • Mucoepidermoid:- Composed of-
    1. Mucus-secreting Cells
    2. Epidermoid-type Cells
  • Carcinoma means malignant epithelial tumor
• The mucus and epidermoid cells are in varying proportions
• Columnar and clear cells are also seen
• Often demonstrate prominent cystic growth
• Most common malignant neoplasm in the major and minor salivary glands
• Accounts for 5% of all salivary gland tumors
• Most common site – Parotid Gland
• Intraorally, most common site is Palate

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CLINICAL FEATURES

• SEX – Slight female predilection
• AGE – Any age but occurs primarily in the third or fifth decades of life, with an average age of 47 years
• Most common malignant salivary gland tumor of children
• Pathogenesis uncertain, although radiation exposure may be one risk factor

• Low Grade Tumor
  • Slow growing
  • Painless mass
  • Rarely exceeds 5 cm in diameter
  • Not completely encapsulated
  • Often contains cyst filled with viscid mucoid material
  • Intraoral Sites – Palate (most common), buccal mucosa, tongue & retromolar areas

• High Grade Tumor
  • Rapidly growing swelling
  • Pain is early symptom
  • Facial nerve paralysis frequent in parotid tumors
  • Other Complains – Trismus, difficulty in swallowing, drainage from ear, numbness of adjacent areas, ulceration (specially in tumors involving minor salivary glands)
  • Not encapsulated, tends to infiltrate surrounding tissue, also many cases metastasize to regional lymph nodes
  • Distant Metastasis Common – Lung, bone, brain & subcutaneous tissue

HISTOPATHOLOGIC FEATURES

• Mucoepidermoid Carcinoma is composed of:
  • Mucus-producing Cells
  • Squamous  (Epidermoid) Cells
  • Intermediate Cells – More important in recognizing mucoepidermoid carcinoma. Highly prolific, basaloid cells. Thought to be a progenitor of both mucous and epidermoid cells

Table Showing Features Of 3 Cell Types Seen In Mucoepidermoid Carcinoma:-

• Some tumors also show variable numbers of clear cells
• Epidermoid, mucous & intermediate cells line cystic space or form solid masses or cords
• Epidermoid & mucous cells may be arranged in glandular pattern
• Cysts may rupture & release mucin. This mucin may pool in the connective tissue And evoke an Inflammatory Reaction

• Traditionally, mucoepidermoid carcinomas have been categorized into one of three histopathologic grades ( LOW/ INTERMEDIATE/ HIGH) based on the following:
  • Amount of cyst formation
  • Degree of cytologic atypia
  • Relative numbers of mucous, epidermoid, and intermediate cells

TABLE SHOWING CRITERIA FOR CATEGORIZING MUCOEPIDERMOID CARCINOMA INTO 3 HISTOPATHOLOGIC GRADES – LOW, INTERMEDIATE & HIGH GRADE TUMOR

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 Variants Of Tumor

• Sclerosing Mucoepidermoid Carcinoma  
• Intraosseous Mucoepidermoid Carcinoma

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TREATMENT & PROGNOSIS

• Low & intermediate-grade mucoepidermoid carcinomas of the parotid gland – Conservative excision with preservation of facial nerve, if possible, recommended
• Affected submandibular gland – Removed entirely
• If patient shows clinical evidence of cervical node metastasis/ T3 lesion – Radical neck dissection is performed
• Treatment for the minor glands – Primarily surgical
• For high grade tumors – Post-op Radiation & chemotherapy

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REFERENCES

• Shafer’s Textbook Of Oral Pathology
• Neville – Oral & Maxillofacial Pathology