Otolaryngology: Salivary Gland Cancer

Salivary Gland Cancer

Location

  • Parotid Gland: 70% – Most Common
  • Submandibular Gland: 8%
  • Minor Glands: 22%
    • Most Common Minor Site: Palatal Mucosa

Prognosis

  • Size: Mn
    • Large Glands: Most are Benign
    • Small Glands: Most are Malignant
  • Location:
    • Parotid Gland: 75-85% are Benign
    • Submandibular Gland: 57-63% are Benign
    • Minor Glands: 85% are Malignant

Presentation

  • Benign Tumors:
    • Mostly Asymptomatic & Often Found Incidentally
    • Painless Slow-Growing Mass
    • Aural Fullness
    • Dysphagia
    • Obstructive Sleep Apnea
    • Trismus
  • Malignant Tumors:
    • Painful Rapidly-Growing Mass
    • Progressive Facial Nerve Paralysis
    • Sialadenitis

Benign Tumors

  • Benign Tumors:
    • Pleomorphic Adenoma – Most Common Benign Tumor (84%)
    • Warthin’s Tumor – Second Most Common Benign Tumor (12%)
    • Cystadenoma
    • Lymphadenoma
    • Myoepithelioma
    • Oncocytoma
    • Sialadenoma Papilliferum
    • Ductal Papilloma
    • Basal Cell Adenoma
    • Sebaceous Adenoma
    • Canalicular Adenoma
  • Other Epithelial Lesions:
    • Sclerosing Polycystic Adenosis
    • Nodular Oncocytic Hyperplasia
    • Lymphoepithelial Lesions
    • Intercalated Ductal Hyperplasia
  • Soft Tissue Lesions:
    • Hemangioma – Most Common Type in Peds
    • Lipoma
    • Nodular Fasciitis
  • Borderline Tumor:
    • Sialoblastoma

Malignant Tumors Mn

  • Mucoepidermoid Carcinoma (MEC) ­– Most Common Malignant Tumor (34%)
  • Adenoid Cystic Carcinoma (AdCC) – Second Most Common Malignant Tumor (22%)
  • Adenocarcinoma – Third Most Common Malignant Tumor (18%)
  • Acinic Cell Carcinoma
  • Squamous Cell Carcinoma
  • Small Cell Carcinoma
  • Lymphoma
  • Metastasis:
    • Most Common Primary Source: Head & Neck Squamous Cell Carcinoma (SCC)
    • Second Most Common Primary Source: Head & Neck Melanoma

Salivary Gland Cancer – Common Tumors

Pleomorphic Adenoma (Benign Mixed Tumor)

  • Most Common Benign Tumor (84%)
  • Path: Mixture of Epithelial & Myoepithelial Cells with Chondromyxoid Stroma
  • In the Parotid Gland, Most Originate in the Superficial Lobe (80-90%)
  • May Have Satellite Nodules or Pseudopodia – Can Cause Recurrence After Excision
  • Can See Malignant Degeneration
    • 1.5% Risk in 5 Years
    • 10% Risk in 15 Years

Warthin’s Tumor (Papillary Cystadenoma Lymphomatosum/Adenolymphoma)

  • Second Most Common Benign Tumor (12%)
  • Most Common in Parotid Gland
  • May Be Bilateral (5-12%)
  • Associated with Cigarette Smoking

Mucoepidermoid Carcinoma (MEC)

  • Most Common Malignant Tumor (34%)
  • Path: Mixture of Cystic & Solid Elements
    • Three Cell Types: Mucous, Squamoid/Epidermoid & Intermediate
  • Mucin Can Impart a Bluish Color to the Tumor

Adenoid Cystic Carcinoma (AdCC)

  • Second Most Common Malignant Tumor (22%)
  • Even Distribution Across All Salivary Glands
    • Overall More Common in Minor Glands than Major Glands
  • Progression:
    • Notorious for Slow, Progressive Infiltrative Growth
    • Invades Nerve Roots & Can Spread by Perineural Lymphatics
    • Often See Late Presentation of Distant Mets Years Later
    • Most Common Site of Mets: Lung
  • Path: Tubular, Cribriform or Solid Growth Pattern

Salivary Gland Cancer – Diagnosis & Treatment

Diagnosis

  • Initial Evaluation: Imaging (MRI/CT)
  • Primary Diagnosis: Fine-Needle Aspiration (FNA)
    • Often Nondiagnostic – Many Tumors Require Demonstration of Invasion Beyond Capsule to Accurately Diagnose
  • Other Options if FNA Nondiagnostic:
    • Repeat FNA
    • Core Needle Biopsy – Higher Risk for Nerve Injury & Tumor Seeding
    • May Require Surgical Specimen for Definitive Diagnosis

Milan System for Staging Salivary Gland Cytopathology

  • Category:
    • Category I: Nondiagnostic
    • Category II: Non-Neoplastic
    • Category III: Atypia of Undetermined Significance (AUS)
    • Category IV: Neoplasm
      • 4i: Benign
      • 4ii: Salivary Gland Neoplasm of Uncertain Malignant Potential (SUMP)
    • Category V: Suspicious for Malignancy
    • Category VI: Malignant
  • Risk of Malignancy:
    • Category I: 25%
    • Category II: 10%
    • Category III:10-35%
    • Category IV:
      • 4i: < 5%
      • 4ii: 35%
    • Category V: 60%
    • Category VI: 90%

Treatment – Benign Tumors

  • Primary Treatment: Surgical Excision
    • Pleomorphic Adenomas Require a Surrounding Cuff of Normal Tissue
  • Extent of Excision:
    • Parotid Gland: Superficial Parotidectomy
    • Submandibular/Sublingual Gland: Gland Excision

Treatment – Malignant Tumors

  • Primary Tumor: Excision & Adjuvant Radiation Therapy
    • Superficial/Lateral Parotid Lobe (Low-Grade & Small): Superficial Parotidectomy
      • Larger Tumors May Require a Partial Deep-Lobe Resection
      • If High-Grade or with Lymph Node Metastases: Total Parotidectomy
    • Deep Parotid Lobe: Total Parotidectomy
    • Submandibular Gland: Gland Excision with Level Ib Lymph Node Excision
    • Sublingual Gland: Wide Local Excision (WLE) with Level I Lymph Node Excision
  • Lymph Node Management:
    • Clinically Negative: Selective Neck Dissection (Controversial)
      • Parotid Tumor: Levels I-IV
      • Submandibular/Sublingual Tumors: Levels I-III
      • *If LN Positive: Modified Radical Neck Dissection (MRND)
    • Clinically Positive: Ipsilateral MRND

Mnemonics

General Prognosis Based on Size

  • MM – Mini are Malignant
  • BB – Big are Benign

Most Common Malignant Tumors

  • M-A-lignant
    • #1: M – Mucoepidermoid
    • #2: A – Adenoid Cystic Carcinoma