malignant sgt

• Types of Salivary Gland Tumors


  • Recognize the types of SGTs
  • Identify tissue of Origin of each tumor
  • Discuss the histology and management

  
• Mucoepidermoid Carcinoma


  Most common salivary malignancy accounting for 29% to 43% of tumors

  
• Mucoepidermoid Carcinoma


  • Parotid 45-70% of cases, Palate 18%
  • Histologically classified into low (slowly growing, painless) and high grade (rapidly growing +/- Pain)
  • Partially encapsulated
  • A higher grade correlates with a poorer outcome
  • Low-grade tumors have a protracted course & higher percentage of mucinous cells
  • Epithelial cells predominate in high-grade. The presence of four or more mitotic figures per 10 high-power fields, neural invasion, necrosis, intracystic component <20%, and cellular anaplasia indicate high-grade behavior
• Mucoepidermoid Carcinoma


  • Parotid>submandibular=minor glands
  • Any age but adults ++
  • Females > males

  
• Histopathology of Mucoepidermoid Carcinoma


  • Epidermoid epithelial cells
  • Intermediate epithelial cells
  • Mucous secreting epithelial cells

  
• Low Grade Mucoepidermoid Carcinoma


  • Composed of numerous mucus secreting cells arranged around microcystic structure with large & numerous intermediate cells and few epidermoid cells with minimal cellular atypia

  
• Intermediate Grade Mucoepidermoid Carcinoma

  • Contains mucus cells & microcystic spaces, but not as numerous as in low grade

  
• High Grade Mucoepidermoid Carcinoma


  • Clusters of proliferating epidermoid cells that are more solid with few mucous cells. Mistaken for SCC (mucin Staining)

  
• Prognosis of Mucoepidermoid Carcinoma


  Related to histological grade (low grade has benign clinical course but with wide metastasis, while high grade has aggressive course with local & distant metastasis into cervical lymph nodes). Intraoral (IO) tumors has poorer prognosis

  
• Treatment of Mucoepidermoid Carcinoma


  1. Stage I & II - Wide local excision

  2. Stage III & IV - Radical excision, +/- neck dissection, +/- postoperative radiation therapy

  
• Adenoid Cystic Carcinoma


  Second most common malignancy overall and the first most common malignancy of the submandibular gland. Characterized by slow growth, neurotropism, local recurrence, and distant metastasis

  
• Adenoid Cystic Carcinoma


  • Adults; Females>males
  • 5% of major gland tumors, but 25% of minor gland tumours
  • Slow growing, may ulcerate or be painful

  
• Histopathology of Adenoid Cystic Carcinoma

  Solid islands, cords, strands of darkly staining epithelial cells in a delicate fibrous connective tissue stroma, however much variation. Notable feature is perineural invasion

  
• Histologic Patterns of Adenoid Cystic Carcinoma


  • Cribriform, tubular, or solid, although the histologic patterns may coexist in the same tumor
  • Cribriform pattern has a glandular architecture and is reported to have the best prognosis
  • Solid pattern is more epithelial in nature and is associated with a poorer prognosis
  • Tubular pattern has a clinical prognosis of intermediate nature between the other two patterns

  
• Cribriform Pattern of Adenoid Cystic Carcinoma


  Characterized by pseudocystic spaces containing mucin (Swiss cheese pattern)

  
• Tubular Form of Adenoid Cystic Carcinoma


  Composed of smallest islands of cells with distinct duct like structure centrally

  
• Solid Pattern of Adenoid Cystic Carcinoma


  Shows little duct formation with large islands of small-medium cells with areas of central necrosis indicate aggressive form of the disease

  
• Perineural Invasion in Adenoid Cystic Carcinoma


  Spread may occur by emboli along the nerve lymphatics
• Treatment of Adenoid Cystic Carcinoma


  1. Complete local excision

  2. Tendency for perineural invasion: (facial nerve sacrifice)

  3. Postoperative XRT

  
• Prognosis of Adenoid Cystic Carcinoma


  • Local recurrence: 42%
  • Distant metastasis: lung
  • Indolent course: 5-year survival 75%, 20-year survival 13%

  
• Acinic Cell Carcinoma


  This tumor has a low-grade behavior and has the best survival rate of any salivary malignancy. Parotid gland was the most common site of origin. Second most common parotid and pediatric malignancy

  
• Acinic Cell Carcinoma


  • Gross pathology: Well-demarcated, most often homogeneous

  
• Histopathology of Acinic Cell Carcinoma


  Classic multicystic pattern. Stained by PAS. Cells heavily stained. Origin: Intercalated duct & reserve cells. Occurs mainly in the parotid gland, also known as blue dot tumor

  
• Acinic Cell Carcinoma


  Lesion is characterized by a benign histomorphologic picture but by occasional malignant behavior

  
• Treatment of Acinic Cell Carcinoma


  Complete local excision, +/- postoperative XRT
• Prognosis of Acinic Cell Carcinoma

  1. year survival: 82%, 10-year survival: 68%, 25-year survival: 50%
• Histopathological Patterns of Acinic Cell Carcinoma


  • Solid (most common), Papillary, Follicular

  
• Malignant Mixed Tumors


  Carcinoma ex-pleomorphic adenoma: Carcinoma developing in the epithelial component of preexisting pleomorphic adenoma

  Carcino-sarcoma: True malignant mixed tumor—carcinomatous and sarcomatous components

  Metastatic mixed tumor: Metastatic deposits of otherwise typical pleomorphic adenoma

  
• Carcinoma ex-Pleomorphic Adenoma


  • Malignant degeneration can occur in 3% to 7% of pleomorphic adenomas. The risk of malignant degeneration is estimated at 1.5% in the first 5 years and 9.5% after 15 years
  • Histologic findings include those of benign pleomorphic adenoma with carcinomatous degeneration
  • A typical clinical history includes a longstanding salivary mass that begins to rapidly enlarge, often to substantial size, although many patients have no history of a prior tumor
  • Fixation of mass to surrounding tissue, ulceration & regional lymphadenopathy. Local recurrence

  
• Gross Pathology of Carcinoma ex-Pleomorphic Adenoma


  Poorly circumscribed, Infiltrative, Hemorrhage and necrosis

  
• Histology of Carcinoma ex-Pleomorphic Adenoma


  Malignant cellular change adjacent to typical pleomorphic adenoma. Carcinomatous component: Adenocarcinoma or Undifferentiated

  
• Treatment of Carcinoma ex-Pleomorphic Adenoma

  Radical excision, Neck dissection (25% with lymph node involvement at presentation), Postoperative XRT

  
• Prognosis of Carcinoma ex-Pleomorphic Adenoma


  Dependent upon stage and histology

  
• Clear Cell Tumor


  Include: Clear cell carcinoma & Epimyoepithelial carcinoma. Low grade tumor (predominantly in minor SG) as submucosal mass in palate. Abundant clear cells

  
• Treatment of Clear Cell Tumor


  Local excision with High recurrence

  
• Squamous Cell Carcinoma of Salivary Glands


  Limited to major salivary glands (SM). Obstructive sialadenitis is predisposing factor. Well to moderately well-differentiated with no evidence of mucin production. 1.6% of salivary gland neoplasms. 7th-8th decades. M:F = 2:1. Must rule out high-grade mucoepidermoid carcinoma, metastatic SCC to intraglandular nodes, or direct extension of SCC

  
• Polymorphous Low Grade Adenocarcinoma


  Low grade malignancy with low risk of recurrence & metastasis. Origin: Reserve cells in most proximal portion of salivary duct. Myoepithelial differentiated cells appear in this neoplasm. Exclusive in minor salivary glands (palate)[second most common malignancy of MSG]

  
• Polymorphous Low Grade Adenocarcinoma


  • Firm, elevated, non-ulcerated nodular swelling. 1-4 cm, slow growth in long duration (yrs). Metastasis in 10% of patients

  
• Morphologic Diversity of Polymorphous Low Grade Adenocarcinoma


  Solid, glandular, cribriform, ductular, tubular, trabecular, cystic

  
• Treatment of Polymorphous Low Grade Adenocarcinoma


  Complete yet conservative excision