(a) overviewPleomorphic adenoma (pleomorphic adenoma) and mixed tumor (mixed, tumor) is the most common salivary gland tumors, is a critical
Pleomorphic adenoma (pleomorphic adenoma) and mixed tumor (mixed, tumor) is the most common salivary gland tumors, is a critical tumor, the pathology of polymorphic, existing neoplastic epithelial tissue, myxoid matrix and cartilage like tissue mixed, so named for the pleomorphic adenoma or mixed tumor. Pleomorphic adenoma is the most common tumor of salivary gland, which is more than 53.9% of all salivary gland tumors. This tumor can occur in any part of the salivary gland, mostly in the parotid gland. In the parotid gland tumors, pleomorphic adenoma account for 60-70%, can occur at any age, from newborn to 80 years of age can occur, but mostly in the age of about 40, the incidence of men and women is similar. Pleomorphic adenoma showed multiple primary tumors, multiple tumors showed one or more parts in the salivary gland and salivary pleomorphic adenoma occurrence. The malignant tumor, malignant transformation rate of about 5-10%.
(two) according to the clinical manifestations, combined with imaging examination, preoperative diagnosis can be more clear.
1 clinical manifestations: in the large salivary gland, pleomorphic adenoma is the most common in the parotid gland, followed by the submandibular gland, located under the very rare. The most common in the small salivary glands is the palate. Any age can occur, but 30-50 years old is more common, more women than men. The tumor grows slowly, often without symptoms, and the history is longer. The tumors were well circumscribed, medium texture, activities, but in the hard palate or mandibular posterior can be fixed without activity; palpation was nodular, more substantial. When the tumor growth period in the slow, sudden acceleration of growth, accompanied by pain, facial paralysis and other symptoms, should consider malignancy.
2 auxiliary examination
(1) B ultrasound: can be used as a routine method for the diagnosis of pleomorphic adenoma, in order to determine the size of the lesion, the location and the relationship with the surrounding anatomy. The results show that the surrounding area is clear, the internal echo is uniform, and the posterior wall is enhanced (Figure 4-6-5). Ultrasonic examination is difficult to determine.
(2) CT examination: tumor CT examination to determine the meaning of deep parotid, circular shape or nodular shape, most edges were clear, mass density close to or higher than the normal parotid gland, the density is uniform, with regular or irregular cystic areas, located in the central part of the central department or partial that mass could be seen around the more or less normal parotid gland; enhanced scan showed homogeneous enhancement. Minor salivary gland pleomorphic adenoma showed clear boundary of the circular, oval or lobulated soft tissue mass; mass density similar to adjacent muscle density, internal uniform density or low density cystic necrosis or calcification spots; enhanced tumor can strengthen change.
3 differential diagnosis
(1) chronic lymphadenitis: salivary gland showed painless mass, often sources of infection, such as inflammation, oral or pharyngeal facial. The masses are often multiple, sometimes large and small, the history of growth and decline, anti-inflammatory treatment is often effective.
(2) lymphatic tuberculosis: submandibular and posterior ear lymph nodes are common, gradually increased, there may be a history of growth and decline, anti tuberculosis treatment can be reduced. There may be a number of masses, a small number of patients with systemic tuberculosis or other systemic history of tuberculosis.
(3) cysts of the parotid gland: slow growth, smooth surface, soft texture, and sometimes wave motion, puncture fluid can be extracted or sebaceous. B ultrasound examination, there were no echo areas in the mass, and the posterior wall and posterior echo enhancement.
Adenoid cystic carcinoma (4) is one of the most common malignant tumors of salivary gland, which can occur at any age. Small salivary gland adenoid cystic disease more than large salivary gland. Sublingual gland malignant tumor, for adenoid cystic carcinoma. Adenoid cystic carcinoma of the salivary gland is the most common malignant tumor in the oral and maxillofacial region. Clinical manifestation: the tumor spreads along nerves, often have neurological symptoms, such as pain, paralysis, numbness wood or hypoglossal nerve palsy. Palatal tumor can spread to the base of the skull. Tumor infiltration is very strong, with the surrounding tissue without boundaries, and sometimes even jumping. The invasion of the tumor is strong, and it is easy to invade the distant metastasis of the blood vessel. The lung is the most common site of metastasis. The cervical lymph node metastasis rate is very low. Adenoid cystic carcinoma is mainly treated by surgery, combined with radiotherapy and chemotherapy.
(5) mucoepidermoid carcinoma (mucoepidermoid carcinoma) is the most common malignant tumor of the salivary gland, which can be seen at any age, mostly in the parotid gland and the palatine gland. Divided into two categories:
1) highly differentiated mucoepidermoid carcinoma is similar to pleomorphic adenoma with a painless mass and slow growth. The size of the tumor is different, the boundary can be clear or unclear, the texture is medium hard, then the surface can be nodular. Well differentiated mucoepidermoid carcinoma in the palate and retromolar sometimes cystic mucous membrane surface, pale blue. The visible during the surgery, the tumor often incomplete or no capsule and no obvious boundaries with the surrounding gland tissue. The sometimes meet nerve tumor adhesion, even tumor wrapped, but rarely appear symptoms of facial paralysis. The blood metastasis of lymph node metastasis is rare, more rare.
2) poorly differentiated mucoepidermoid carcinoma with rapid growth, pain. The boundary is not clear, and the surrounding tissue adhesion. Parotid gland tumors often involve facial nerve. The lymph node metastasis rate is high, and there may be hematogenous metastasis. The treatment of mucoepidermoid carcinoma with local excision is the main treatment method.
The treatment of pleomorphic adenoma is surgical resection, and the surgical procedure is the key to successful treatment. Can do simple tumor enucleation, namely enucleation, and do tumor normal tissue resection. The tumors located in the superficial lobe of parotid gland, tumor resection and generally do superficial lobe tumors located in the parotid gland; after the lower pole can be used, tumor and normal gland tissue regional excision; the tumors located in the deep lobe of the parotid gland, tumor resection of parotid gland and to do the surgery, should be the preservation of the facial nerve. Submandibular gland pleomorphic adenoma, together with submandibular gland and complete resection of the tumor. Small salivary gland tumors should be removed from the normal tissue of the marginal 0.5cm.
(four) prognosis: strict adherence to the principle of surgical treatment of pleomorphic adenoma, few recurrence after surgery. The first operation is the main factor affecting the prognosis.
(five) the latest progress and Prospect: the features of pleomorphic adenoma of salivary gland histology determines the nature of the tumor, but its biological behavior also reflects the characteristics of its recurrence, although the recurrence of human factors significantly, but the critical characteristics of recurrent tumor after all is decided by the biological characteristics of tumor cells. Although there are certain tumor cell proliferation activity of recurrence increased significantly, but still can not fully explain the change of tumor from primary to postoperative recurrence or canceration. The human factors can not be avoided, but why the same operation the same region of the tumor, while others rarely relapse or recurrence; mixed tumor recurrence and why in parotid and submandibular gland is not common, the tumor recurrence is related to the organizational environment, these problems still need further research.