--- title: "Malignant Salivary Gland Tumors" description: "ENT notes on Malignant Salivary Gland Tumors - Causes, WHO Classification, Symptoms, Investigations and Treatment." source: "The ENT Resident" author: "Dr. Mausumi Das" canonical_url: "https://www.theentresident.com/ent-notes-lectures/malignant-salivary-gland-tumors" categories: ["Oral Cavity and Salivary Glands"] video: "https://www.youtube.com/watch?v=raJAxBdBC8c" image: "https://media.theentresident.com/og-images/malignant-salivary-gland-tumors.png" --- # Malignant Salivary Gland Tumors ENT notes on Malignant Salivary Gland Tumors - Causes, WHO Classification, Symptoms, Investigations and Treatment. Watch the full video lecture on YouTube: https://www.youtube.com/watch?v=raJAxBdBC8c ## 🧬 Malignant Salivary Gland Tumors Malignant salivary gland tumors are **uncommon head and neck malignancies** with diverse histology, variable clinical behavior, and complex management strategies. Understanding their **risk factors, histogenesis, clinical presentation, staging, classification, investigations, and treatment** is essential for ENT examinations and clinical practice. --- ### 📌 Incidence & Epidemiology of Malignant Salivary Gland Tumors - Incidence: **~0.5 per 1 lakh population per year** - Account for **< 5% of all head and neck cancers** - Less common than **benign salivary gland tumors** - Incidence increases **after the 5th decade of life** --- ### ⚠️ Risk Factors for Malignant Salivary Gland Tumors **1️⃣ Radiation Exposure (Most Important)** - **Atomic bomb survivors** - Increased risk of **mucoepidermoid carcinoma** - **Therapeutic head & neck radiation** - Especially childhood cancers > What is the usual latent period between radiation exposure and development of Malignant Salivary Gland Tumors? **2️⃣ Occupational Exposure** Increased risk with exposure to: - Rubber - Nickel - Asbestos - Silica dust - Plumbing, woodworking, mining industries 📌 **Livestock feed processing** - Exposure to **mycotoxins** (produced by *Aspergillus*) - Highly carcinogenic **3️⃣ Viral Associations** (Not conclusively proven) - **Epstein–Barr virus (EBV)** → Undifferentiated parotid carcinoma - **Cytomegalovirus (CMV)** → Mucoepidermoid carcinoma **4️⃣ Nutritional Factors** - **Inverse relationship** with diet rich in **polyunsaturated fatty acids** - Higher PUFA intake → lower salivary gland cancer risk **5️⃣ Genetic & Molecular Alterations** - **Mucoepidermoid carcinoma** → *CRTC1–MAML2* gene fusion - **Adenoid cystic carcinoma** → *MYB–NFIB* gene fusion --- ### 🧠 Histogenesis of Malignant Salivary Gland Tumors 🔹 **1. Multicellular Theory** (Older) Each tumor arises from a **specific mature cell type** of the salivary gland. | Cell of Origin | Tumor Type | | --- | --- | | Acinar cells | Acinic cell carcinoma | | Intercalated duct cells | Adenoid cystic carcinoma, Polymorphous adenocarcinoma | | Excretory duct cells | Mucoepidermoid carcinoma, Salivary duct carcinoma, SCC | | Myoepithelial cells | Myoepithelial carcinoma, Basal cell adenocarcinoma | > ➡️ Multiple cells of origin → **multicellular theory** 🔹 **2. Reserve Cell (Stem Cell) Theory** (Most Accepted) - All tumors arise from a **single undifferentiated pluripotent reserve cell** - Normal salivary gland & tumors arise via **differentiation** - **Earlier differentiation error → higher grade malignancy** >➡️ Reserve Cell Theory explains wide histological diversity > What is the risk (%) of malignancy in Parotid, submandibular, sublingual and Minor salivary glands? 📌 **Smaller the gland → higher the malignancy risk** --- ### 🩺 Clinical Features of Malignant Salivary Gland Tumors #### 🔹 Parotid Gland - Painless pre-/infra-auricular swelling - **Deep lobe tumors** → soft palate / oropharyngeal bulge - **Accessory parotid tumors**: ~1% > What is the most common site of origin of malignant salivary gland tumor in Parotid? > What are the Features Suggestive of Malignancy in a parotid malignancy? #### 🔹 Submandibular Gland - Slow-growing painless swelling in submandibular triangle - May distort floor of mouth - Pain (30%), cervical nodes (25%) > What are the common nerves involved in malignant salivary gland tumor in Submandibular Gland? #### 🔹 Minor Salivary Glands - Can arise anywhere - Painless submucosal swelling - Central ulceration - Ill-fitting dentures (important clue) - Pain / paresthesia (~25%) > What is the most common site of origin of malignant salivary gland tumor in Minor Salivary Glands? --- ### 🧪 TNM Staging (Salivary Gland Tumors) **T Staging** - **T1:** ≤ 2 cm, no extraparenchymal extension - **T2:** > 2–4 cm, no extraparenchymal extension - **T3:** > 4–6 cm and/or extraparenchymal extension - **T4a:** Tumor invades Skin, mandible, ear canal, and/or facial nerve - **T4b:** Tumor invades Skull base, and/or pterygoid plates, and/or encases carotid artery **N Staging** - **N1:** Single ipsilateral node ≤ 3 cm, no extranodal extension - **N2a:** Single ipsilateral node > 3–6 cm, no extranodal extension - **N2b:** Multiple ipsilateral < 6 cm - **N2c:** Bilateral/contralateral < 6 cm - **N3a:** > 6 cm, no extranodal extension - **N3b:** Any node with extranodal extension **M Staging** - **M0:** No distant metastasis - **M1:** Distant metastasis --- ### 🧬 Classification of Malignant Salivary Gland Tumors **22 malignant salivary gland tumor types**, common ones include: - Mucoepidermoid carcinoma - Adenoid cystic carcinoma - Acinic cell carcinoma - Polymorphous adenocarcinoma (formerly PLGA) - Salivary duct carcinoma - Myoepithelial carcinoma - Carcinoma ex-pleomorphic adenoma - Squamous cell carcinoma - Neuroendocrine carcinomas - Lymphoepithelial carcinoma - Sialoblastoma --- ### 🔸 Acinic Cell Carcinoma - Low-grade tumor (~3%) - 90% parotid - Female predominance - Encapsulated, solid/microcystic patterns - Rare facial nerve or nodal involvement --- ### 🔸 Polymorphous Adenocarcinoma - Minor salivary glands (palate) - Low-grade, indolent - Late recurrence (10–15 years) - Mimics pleomorphic adenoma & adenoid cystic carcinoma --- ### 🔸 Adenocarcinoma (NOS) - Aggressive - Perineural invasion - Facial nerve involvement (~20%) - Poor prognosis --- ### 🔸 Carcinoma ex-Pleomorphic Adenoma - Malignancy in pre-existing pleomorphic adenoma - Risk increases with duration - Poor prognosis --- ### 🔍 Investigations of Malignant Salivary Gland Tumors **A. Imaging** - **Ultrasound**: First line + FNAC guidance - **CECT**: Large tumors, nerve involvement, nodes - **MRI**: Best soft-tissue delineation, perineural spread - **PET-CT**: Staging (false positives in Warthin’s & pleomorphic adenoma) **B. Cytology** - **FNAC** – initial test - **Core biopsy** – if FNAC inconclusive --- ### 🛠️ Treatment of Malignant Salivary Gland Tumors #### 🔹 Surgery (Mainstay) **A. Parotid** - Superficial parotidectomy - Total / Radical parotidectomy > What are the indications of Superficial parotidectomy & Total / Radical parotidectomy in Malignant Parotid Tumors? > What are the indications of Facial nerve resection in Malignant Parotid Tumors? --- **B. Submandibular Gland** - Early, N0 → Gland excision + Level I - Advanced → Levels I–III or comprehensive neck dissection --- **C. Sublingual & Minor Salivary Glands** - Wide local excision - N-block resection for large tumors - Elective neck dissection often indicated --- **🔹 Neck Management** - **Clinically N+** → Modified radical neck dissection - **Pathologically N+** → Adjuvant radiotherapy - **Clinically N0** → Elective neck treatment if high-risk --- #### ☢️ Adjuvant Radiotherapy in Malignant Salivary Gland Tumors **Indications:** - T3–T4 tumors - High-grade histology - Perineural / vascular invasion - Positive margins - Multiple nodes --- #### 💊 Chemotherapy in Malignant Salivary Gland Tumors - Limited role - Palliative - Best response in adenocarcinoma NOS - Drugs: Cisplatin, Doxorubicin, Cyclophosphamide --- ### 📌 Exam Pearls - **Smaller gland → higher malignancy risk** - Facial nerve palsy = malignancy until proven otherwise - MRI best for perineural spread - Surgery is the cornerstone of treatment - Radiotherapy is adjuvant, chemotherapy mostly palliative --- ## About This Note This free ENT note on Malignant Salivary Gland Tumors was written by Dr. Mausumi Das and is paired with a corresponding video lecture. 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