In the salivary glands (lat. glandulae salivariae), as in all other tissues of the body, both benign and malignant tumors can develop. Within the benign (benign) salivary gland tumors, the monomorphic tumors are distinguished from the pleomorphic adenoma – colloquially called salivary gland mixed tumor – (ICD-10: D 11.0 – Benign neoplasm: parotid gland; D 11.7 – Benign neoplasm: other major salivary glands; D 10.3 – Benign neoplasm: other and unspecified parts of the mouth. Incl: Minor salivary glands unspecified) distinguished. Benign salivary gland tumors usually occur in the region of the major salivary glands such as the parotid (parotid gland), but may also affect the minor salivary glands.Pleomorphic adenoma is the most common tumor of the salivary glands, accounting for 45-75 percent. It occurs particularly in the area of the parotid gland. Mostly middle-aged people are affected. Women are more frequently affected than men. The tumor grows very slowly and does not cause damage to the facial nerve. This nerve, which runs in the parotid gland among other places, supplies the mimic muscles of the face and is often damaged in malignant tumors of the parotid gland, which can lead to failures of the muscles of the affected half of the face.Therefore, if the nerve is damaged, a malignant degeneration of a pleomorphic adenoma should always be considered.
Symptoms – Complaints
This tumor does not cause any symptoms. The diagnosis is often made by chance. Occasionally, affected patients notice swelling and present to their physician or dentist for this reason. The pleomorphic adenoma has a smooth surface and its consistency is described as impingement-elastic. The tumor is displaceable because it does not infiltrate into the surrounding tissue, which is a sign of its benign nature.
Pathogenesis (disease development) – etiology (causes)
Pleomorphic adenoma is thought to develop from neoplastic (new-forming) proliferating epithelial cells. There are no known risk factors for the development of this tumor.
Consequential diseases
This is a benign tumor that in some cases, approximately 1-5%, may malignantly degenerate, that is, the tumor becomes malignant. This is particularly observed in recurrent pleomorphic adenomas. In this case, a sudden increase in the size of a swelling that has already existed for some time often occurs. Sudden signs of facial damage may also be an indication of malignant degeneration. After removal, the tumor tends to recur, the new appearance of the tumor, in about ten percent of cases.
Diagnostics
A pleomorphic adenoma is suspected in the presence of a sliding, impinging tumor without damage to the facial nerve. Both sonography (ultrasound) and magnetic resonance imaging of the head (cranial MRI; cMRI) are used for imaging. Biopsy should not be performed even if benign pleomorphic adenoma is suspected, as this would destroy the capsule of the tumor and thus allow the tumor cells to enter the surrounding tissue, which in turn leads to multiple recurrences.
Therapy
In the presence of pleomorphic adenoma, removal of the affected gland is usually the treatment of choice because of the high recurrence rate (recurrence of the disease) and the risk of malignant (malignant) degeneration. In the area of the parotid gland, this is called a parotidectomy. Depending on the extent of the tumor, a lateral or partial parotidectomy or a total removal of the parotid gland is performed.In benign tumors, such as pleomorphic adenoma, the facial nerve is preserved so that the function of the facial mimic muscles is maintained. Intraoperative damage to the nerve is one of the risks of surgery, but is rare. Nevertheless, if the pleomorphic adenoma is removed, a safety margin must be maintained to minimize the risk of recurrence. If the tumor is injured intraoperatively, there is a risk of tumor cell distribution in the tissue, which would result in multiple recurrences. After removal of the parotid gland, patients may experience the so-called Frey syndrome, or gustatory sweating. In this case, the affected person experiences sweating in the area of the cheek when eating.This phenomenon is due to the fact that the nerves that previously supplied the salivary gland have now lost their target organ and mistakenly grow into the sweat glands of the skin, stimulating them to secrete sweat every time food is ingested. Today, however, there are numerous techniques to prevent this already intraoperatively, for example by sewing in a muscle flap, which thus prevents the nerves from growing into the sweat glands of the cheek.If Frey’s syndrome nevertheless occurs, this can now be treated by local therapy with botulinum toxin, among other methods.