The parotid glands are the largest of the three major salivary glands, located just in front of each ear and extending down to the angle of the jaw. These glands produce serous saliva, which aids in digestion and keeps the mouth lubricated. A benign parotid tumor is a non-cancerous growth of cells within this gland, meaning it cannot spread to distant parts of the body. Despite the reassuring diagnosis, deciding whether to remove the growth is complex, requiring a careful balance of potential risks versus long-term complications.
Why Removal is Generally Recommended
A benign parotid tumor is typically recommended for surgical removal due to two main concerns: the potential for malignant transformation and the effects of local growth. The most common type, Pleomorphic Adenoma, carries a small but measurable risk of becoming cancerous over time, transforming into carcinoma ex pleomorphic adenoma. This risk increases significantly the longer the tumor remains in the gland, rising to approximately 10% after 15 years.
The constant, slow growth of the tumor presents a separate set of problems, even if it never turns malignant. As the mass enlarges, it can cause a noticeable lump or asymmetry on the face or jaw. Larger tumors can also exert pressure on nearby structures, potentially leading to discomfort or pain. Furthermore, a tumor that grows extensively deep into the gland tissue makes eventual surgery more difficult and increases the chance of damage to surrounding nerves.
Removing the tumor when it is small minimizes the extent of the surgery required and offers the best chance for a complete cure. The goal is to prevent the growth from reaching a size where it might compromise the delicate facial nerve or necessitate a more extensive operation. For most benign tumors, prophylactic surgical removal is seen as the most reliable way to eliminate the risk of future malignancy and prevent local complications.
When Watchful Waiting is Appropriate
While surgery is the preferred approach for many benign growths, a strategy of active surveillance, or watchful waiting, may be appropriate under specific circumstances. This approach is most commonly reserved for Warthin’s tumor, the second most frequent benign parotid tumor. Unlike Pleomorphic Adenoma, Warthin’s tumors have a very low probability of malignant transformation, making the immediate oncologic risk negligible.
Patient-specific factors also weigh heavily in the decision to observe the lesion rather than operate immediately. For elderly patients or those with serious co-existing medical conditions that make general anesthesia or lengthy surgery high-risk, avoiding an elective procedure may be the safer choice. Tumors that are very small and located in a favorable position, such as the tail of the parotid gland, may also qualify for observation if they are not actively growing.
Watchful waiting requires a strict protocol of regular monitoring. Patients must undergo periodic clinical examinations and follow-up imaging, typically with ultrasound or MRI, to track the tumor’s size and characteristics meticulously. If the tumor shows any sign of accelerated growth, or if the patient develops new symptoms, the management strategy will quickly shift back toward surgical removal.
Surgical Procedure and Potential Risks
The removal of a parotid tumor is a complex procedure performed by specialists, most often a head and neck surgeon, due to the intricate anatomy of the region. The facial nerve, which controls all the muscles of facial expression, runs directly through the middle of the parotid gland. The specific surgical approach, a parotidectomy, is determined by the tumor’s location. A superficial parotidectomy removes the outer portion of the gland, while a total parotidectomy removes both lobes.
The primary risk of this surgery is injury to the facial nerve, which can result in temporary or permanent facial weakness or paralysis. Surgeons use meticulous dissection techniques and often employ intraoperative nerve monitoring to identify and protect the nerve and its five main branches. Temporary facial weakness occurs in a significant number of patients, ranging from 18% to 65%, due to nerve stretching or manipulation, though this typically resolves over several weeks or months.
Permanent injury to a branch of the facial nerve, resulting in lasting facial drooping or asymmetry, is less common, with reported rates between 0% and 19%. Other common complications include numbness of the earlobe, which results from the unavoidable sacrifice of the greater auricular nerve. A potential long-term issue is Frey’s syndrome, where the patient experiences flushing or sweating on the cheek skin over the surgical site while eating, a condition known as gustatory sweating.
Understanding Long-Term Recurrence
While surgical removal is intended to be curative, a benign tumor may return years after the initial procedure. The recurrence rate for Pleomorphic Adenomas is generally low, typically between 1% and 5%, when the tumor is removed completely using a formal parotidectomy technique. However, recurrence rates can be significantly higher, up to 20% to 45%, if the initial surgery was a more limited excision that inadvertently left behind microscopic tumor cells.
The main factor contributing to recurrence is the microscopic rupture or breach of the tumor’s thin capsule during the initial operation. This leads to the spillage of tumor fragments into the surrounding tissue. These spilled cells can lie dormant for many years before growing into new tumor nodules, often presenting as multiple small masses rather than a single lump.
A recurrent parotid tumor is more challenging to treat because the previous surgery creates dense scar tissue. This scar tissue makes the subsequent operation more technically demanding. Repeat surgery on a recurrent tumor carries a higher risk of permanent facial nerve injury compared to the first operation due to the distortion of the normal anatomy.