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 (mucinStaining)
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 submandibulargland. 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)
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
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