Salivary Gland Neoplasms

Posted by e-Medical PPT Monday, December 19, 2011
Mucoepidermoid Carcinoma
Most common salivary malignancy accounting for 29% to 43% of tumors
Mucoepidermoid cancer is histologically classified into low and high grade. A higher grade correlates with a poorer outcome
Low-grade tumors have a 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.

Adenoid Cystic Carcinoma
Adenoid cystic carcinoma is the most common malignancy of the submandibular gland
Adenoid cystic carcinoma is characterized by slow growth, neurotropism, local recurrence, and distant metastasis.
Exhibits a predilection for neurotropic spread, often leading to recurrences at the skull base after surgical and radiation treatment
Three distinct histologic patterns, cribriform, tubular, or solid, although the histologic patterns may coexist in the same tumor
The cribiform pattern has a glandular architecture and is reported to have the best prognosis.
The solid pattern is more epithelial in nature and is associated with a poorer prognosis.
The tubular pattern has a clinical prognosis of intermediate nature between the other two patterns.

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

Carcinoma ex-Pleomorphic Adenoma 
Malignant degeneration can occur in 3% to 7% of pleomorphic adenomasThe 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

Diagnosis
Malignant salivary neoplasms present as a painless mass in approximately 75% of patients. Rarely,  patients are initially seen with pain or facial nerve palsy.
A palpable mass arising in a salivary gland, associated with pain, and/or nerve paralysis is more likely to be malignant than benign.
It is believed that episodic pain suggests continued obstruction, whereas constant pain is more suggestive of malignancy.
Trismus, cervical adenopathy, fixation, numbness, loose dentition, or bleeding also suggest the presence of malignancy.

Fine Needle Aspiration Biopsy
Traditionally, FNA has been performed preoperatively for histologic confirmation of malignancy and to aid in operative planning, such as planning for elective neck dissection
They found that FNA had a 90% sensitivity for malignancy if non-diagnostic biopsies were excluded...

Treatment – The Primary
Total parotidectomy may be necessary for tumor extension into the deep parotid lobe or when the tumor primarily arises in the deep lobe. This can be performed with preservation of the facial nerve
Occasionally, patients may require extended parotidectomy, which includes resection of the masseter muscle or the ascending portion of the mandible.
Facial nerve sacrifice is not routinely advocated. Nerve preservation in primary salivary malignancy is recommended if the nerve is functioning normally before surgery. Every attempt to dissect the tumor from the individual branches should be undertaken. If tumor is completely encasing the nerve branches, neural sacrifice is limited to the involved branches.

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