Mucoepidermoid Carcinoma

🧬 Mucoepidermoid Carcinoma

• Seen in both adults and children

• Accounts for ~ 5% of all salivary gland tumors

• Female preponderance

• Peak incidence: 5th decade (range: 3rd–8th decade)

Which is the only salivary gland tumor with male predominance?

Which is the most common salivary gland tumor overall?

Which is the most common malignant salivary gland tumor?

🧠 Definition of Mucoepidermoid Carcinoma

Mucoepidermoid carcinoma is a malignant epithelial tumor of salivary glands composed of variable proportions of three cell types:

1. Mucus secreting cells
2. Epidermoid (squamoid) cells
3. Intermediate cells

These cells form cystic and solid architectural patterns.

🧬 Histogenesis of Mucoepidermoid Carcinoma

• Arises from pluripotent reserve (stem) cells of the ductal system

• These reserve cells differentiate into:

  • Mucus cells
  • Epidermoid (squamous) cells
  • Intermediate cells

🧬 Risk Factors of Mucoepidermoid Carcinoma

• Prior radiation exposure (important association)

🔬 Pathology of Mucoepidermoid Carcinoma

Gross (Macroscopic) Features

• Well circumscribed tumor
• No true capsule
• Margins often infiltrative
• Cut section:
  • Pale grey to white
  • Multiple mucin filled cystic spaces

Microscopy (Histology)

1. Mucus-Secreting Cells

2. Epidermoid Cells

3. Intermediate Cells (Basaloid cells)

Describe the appearance of the cells found in histology of Mucoepidermoid Carcinoma.

🧪 Histological Grading of Mucoepidermoid Carcinoma

🔹 Low Grade Mucoepidermoid Carcinoma

• Predominantly mucus cells
• Numerous cystic spaces
• Abundant mucin
• Minimal cellular atypia
• Resembles benign tumors

🔸 Intermediate Grade Mucoepidermoid Carcinoma

• Mucus and epidermoid cells roughly equal
• Fewer and smaller cysts
• Increased pleomorphism
• Increased mitotic figures

🔺 High Grade Mucoepidermoid Carcinoma

• Predominantly epidermoid cells
• Solid nests and cords
• Minimal cystic spaces
• Marked nuclear pleomorphism
• High mitotic activity

🩺 Clinical Features of Mucoepidermoid Carcinoma

🔹 Low Grade Tumors

• Slowly enlarging

• Painless mass

• Often < 5 cm

• Cystic, mucoid content

• Not encapsulated

🔺 High-Grade Tumors

• Rapid growth

• Pain

• Facial nerve paralysis

• Trismus

• Dysphagia

• Ear discharge

• Numbness of adjacent areas

• Ulceration

• Regional lymph node metastasis

• Distant metastasis

What are the common sites of distant metastasis in Mucoepidermoid Carcinoma?

What is the most common gland involved in Mucoepidermoid Carcinoma?

What is the Most common intraoral site involved in Mucoepidermoid Carcinoma?

🔍 Investigations of Mucoepidermoid Carcinoma

1. Ultrasound

• First-line imaging

• FNAC guidance

1. Contrast-Enhanced CT / MRI

• MRI preferred (gold standard for soft tissue)

• Assesses:

  • Tumor extent
  • Deep lobe involvement
  • Bone erosion
  • Skull base invasion
  • Perineural spread (best seen on MRI)

1. FNAC

• Diagnostic confirmation

1. Chest X-ray

• Screening for distant metastasis

🛠️ Treatment of Mucoepidermoid Carcinoma

🔹 Primary Treatment: Surgery

Parotid Gland

• Low-grade, superficial lobe:

  • Superficial parotidectomy
  • Facial nerve preservation

• High-grade / deep lobe / > 4-5 cm:

  • Total conservative parotidectomy
  • Preserve facial nerve if uninvolved
  • Nerve sacrifice + grafting if involved

Submandibular / Sublingual Gland

• Complete excision of gland with margins

Minor Salivary Glands

• Wide local excision
• Adequate soft tissue + periosteal/bony margins
• Reconstruction as required

What are the indications of Adjuvant Radiotherapy in Mucoepidermoid Carcinoma ?

🔹 Neck Management

• Clinically N+ neck:

  • Radical neck dissection

What are the indications of Elective neck dissection in Clinically N0 neck?

💊 Chemotherapy in Mucoepidermoid Carcinoma

• Very limited role
• Mainly palliative

📊 Prognosis of Mucoepidermoid Carcinoma

• Low grade MEC: Excellent prognosis with adequate surgery

• Intermediate / High grade MEC:

  • Higher risk of:

    • Local recurrence
    • Nodal metastasis
    • Distant metastasis

  • Prognosis depends on grade and stage

📌 Exam Pearls

• Most common malignant salivary gland tumor
• Triad of cells: mucus + epidermoid + intermediate
• Low-grade MEC can mimic pleomorphic adenoma
• MRI best for perineural spread
• Histological grade determines prognosis