Submandibular Gland Tumors

As in all salivary gland tumors surgery is the primary modality of treatment. When the diagnosis is established preoperatively as benign PA by FNAB, then an extracapsular excision of the sub-mandibular gland is indicated (Figures 9.6 and

9.7). Pleomorphic adenomas should be treated in the same manner as for the parotid gland (see chapter 8). There is some evidence that the capsule of PAs in the submandibular gland is thinner than in the parotid (Webb and Eveson 2001), and it is important to maintain a margin of normal tissue around the tumor. If the entire gland and tumor is not removed but the PA merely enucleated, there is a higher risk of recurrence (Laskawi et al. 1995). In this dissection it is easy to maintain a little extra fat and connective tissue over areas where the PA may approach the surface of the gland (Figure

9.8). In a series of 15 PAs of the submandibular gland 20% were in the surface of the gland

Submandibular Incision With Name

Figure 9.6a. The incision for submandibular gland tumor removal lays approximately 1-2 finger-breadths below the lower border of the mandible and is placed in a natural skin crease.

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Figure 9.6b. The submandibular gland is separated from its duct, which is indicated by the sharp scissors. The arrow points to the tumor in the hilum.
Submandibular Gland Tumor

Figure 9.7. Another case of submandibular pleomorphic adenoma dissected to the duct. The larger tumor at the hilum is indicated by the arrow.

Figure 9.6c. Surgical specimen with arrow indicating PA.

Figure 9.6d. Histopathology shows pleomorphic adenoma of submandibular gland.

(Laskawi et al. 1995) (Figure 9.9). The marginal mandibular branch of the facial nerve lies between the platysma superficially and the capsule of the submandibular gland (superficial layer of the deep cervical fascia) deeply and can be preserved either by dissecting it along its course and retracting it superiorly or by ligating and cutting the anterior

Figure 9.7. Another case of submandibular pleomorphic adenoma dissected to the duct. The larger tumor at the hilum is indicated by the arrow.

facial vein inferior to the nerve and using traction on the tied distal end of the vessel to retract the nerve out of the field (the Hayes Martin maneuver). The incidence of transient palsy of the marginal mandibular branch of the facial nerve is 7% in excising benign tumors and 21% in excising malignant tumors, with only 1 case (<1%) of permanent palsy in this series (Preuss, Klussmann, and Wittekindt et al. 2007). The facial artery is sacrificed if it passes through the gland itself, but if not its numerous small branches including the submental branch can be clipped and the main vessel preserved.

In recurrent PA the disease will frequently be multinodular as in the parotid, and as 45% of these cases involve the subcutaneous tissue under the previous operative scar, excision of the scar with a margin of the surrounding skin is recommended as part of the en bloc excision (Laskawi et al. 1995).

Where a definite diagnosis of a benign tumor is not established preoperatively or when a low-grade malignant tumor is diagnosed, an en bloc resection of level I is safest. If the final histologic diagnosis is benign no important structures have been sacrificed, only the gland and tumor plus fat with lymph nodes. If the tumor is a low-grade malignancy, then no further surgery is indicated. In the case of a high-grade tumor a selective or radical neck dissection can be completed at the same time (Figure 9.10).

Figure 9.8c. High-power axial CT scan shows the tumor marked with a circle.

Figure 9.8a. Axial CT shows tumor projecting beyond the gland surface.

Myelohoid Muscl Scan

Figure 9.8d. Operative picture showing the tumor marked by palpation.

Figure 9.8b. Coronal CT confirms the surface Figure 9.8e. Intraoperative view of extracapsular dissec-involvement. tion preserving soft tissue over the tumor surface.

Figure 9.8f. Surgical specimen.

In undertaking the level I dissection the cervical skin flap is lifted in a subplatysmal plane and the marginal mandibular branch of the facial nerve is preserved. The anterior belly of the digastric muscle is identified and its fascia dissected free. The fascia is dissected off the mylohyoid muscle, freeing the fat and nodes from the digastric, mylo-hyoid, and inferior border of the mandible. The posterior edge of the mylohyoid muscle is retracted to identify the lingual nerve, which is preserved if it is uninvolved by cutting the branch to the gland and allowing the nerve to retract into the mouth. The duct is sectioned and the facial vein and artery tied off or dissected free as indicated to release the specimen. In low-grade N0 tumors a neck dissection is usually not indicated, but the excision can be extended to encompass lymph node levels II and III as a supraomohyoid neck dissection. If lymph nodes are clinically involved, then a type I modified radical neck dissection is required.

In high-grade tumors or advanced low-grade tumors with extracapsular infiltration and involvement of the skin, muscle, or mandible extended resections with incorporation of these structures will be necessary to obtain clear margins. These resections will be dictated by the size and extent of the tumor. In N0 cases selective neck dissection levels I-III or I-IV will be used and modified radical neck dissections for clinically positive necks. In the case of ACC, widespread infiltrative growth beyond the palpable tumor makes obtaining clear margins challenging. The propensity for perineural inva sion with ACC will necessitate sacrifice of involved nerves, for example, lingual, hypoglossal, and facial, tracing the nerves proximally using frozen section guidance to determine clearance. Unfortunately, "skip" metastases can occur along the nerve and a negative frozen section is no guarantee of success. ACC is more prone to metastasize hematogenously than through lymphatics such that a selective neck dissection is usually sufficient.

Postoperative radiation therapy is administered for high-grade tumors, positive margins, positive nodes, and perineural spread if re-resection is not possible. Chemotherapy has not been shown to improve survival in salivary gland cancer.

Prognosis will depend on the histologic grade and the stage of the tumor. Some authors (Anderson, Thrkildsen, and Ockelman et al. 1991) have found a crude 10-year survival of 50% with 10% local recurrence and 39% of cases having metastasized at the time of diagnosis. In the series reported by Rapidis et al. (2004), 8 of 14 patients died during follow-up with a survival rate of 38.5%, but 11 of 14 of these patients presented with stage III or IV disease. Bhattacharyya (2004) analyzed 370 cases of submandibular gland cancer from the SEER database and reported a 59.7% 5-year survival; however, this figure is high, as 42.2% of his cases were ACC with a mean survival of 99 months. In the same series the patients with squamous cell carcinoma had a mean survival of 52 months. Younger age, low-grade histology, and the use of radiation therapy were factors in improving survival. Weber, Byers, and Petit et al. (1990) found a 69% 5-year survival, with extracapsular infiltration and lymph node metastases indicating a poor prognosis. Stages TI-TIVA had a case-specific 5-year survival of 88% compared to 55% for T4B, and 5-year survival of 86% for negative nodes compared to 30% for positive nodes.

Most published series have found a survival benefit conferred by radiation therapy, with 75% of patients receiving adjuvant radiation in one study (Camilleri et al. 1998). Storey, Garden, and Morrison et al. (2001) report actuarial locoregional control of 88% at 5 and 10 years; however, the corresponding disease-free survival rates were 60% and 53% due to 36% of patients with locore-gional control developing distant metastases.

Figure 9.9a. Submandibular gland attached only by its duct. The pleomorphic adenoma is large and hangs beneath the gland attached only by the enveloping fascia of the capsule.
Parotid Swelling Old Man
Figure 9.10a. 82-year-old man with pain and swelling of the right submandibular region.
Submandibular Gland Tumor

Figure 9.9b. Surgical specimen with arrows pointing to the large PA, which has no real attachment to the gland.

Figure 9.10b. CT scan confirms a submandibular gland mass diagnosed as malignant on fine needle aspiration biopsy.

Figures 9.10c and 9.10d. Intraoperative figures showing level I excision combined with a selective neck dissection in view of high-grade cytology.

Figures 9.10f and 9.10g. Hematoxylin and eosin stain (f) and Alcian Blue stain (g) confirm a diagnosis of high-grade mucoepidermoid carcinoma.

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Figure 9.10e. Operative specimen.

Figure 9.10h. One year postoperative view of the patient. He died 3 years postoperatively with distant metastases of the lung.

Nonetheless the median survival time for patients with locoregional control was 183 months compared to 19 months for those patients without locoregional control. In a similar study of adjuvant radiation therapy, cancer-specific survival was 79% and 57% at 5 and 10 years, with local control of 85% and 74%, respectively. Twenty percent of patients (all ACC) developed distant metastases (Sykes et al. 1999). A retrospective study of 87 patients that compared patients who received either initial enucleation of the gland (subcapsular dissection) with no evidence of residual primary or nodal disease followed by postoperative radiation therapy; or who had evidence of gross residual primary or nodal disease, grossly positive margins, or piecemeal removal following initial treatment who underwent definitive surgical resection followed by postoperative radiation therapy, found no difference in locoregional control, disease-specific survival, or overall survival (Kaszuba,

Zafero, and Rosenthal et al. 2007). This suggests patients without evidence of gross residual disease post-enucleation might be satisfactorily treated with radiation therapy without further surgery.

In a series of 22 patients with ACC of the submandibular gland, disease-free survival at 5 years of 57% and 10 years of 41% and overall survival of 70% and 37%, respectively, were found (Cohen, Damrose, and Huang et al. 2004). These authors concluded that early diagnosis, wide surgical intervention, and postoperative radiotherapy were associated with a favorable prognosis, while not surprisingly large tumor size, positive surgical margins, perineural invasion, and local recurrence were negative prognostic factors.

In comparing submandibular gland cancers to parotid cancer a poorer overall prognosis was associated with submandibular gland tumors (Hocwald, Korkmaz, and Yoo et al. 2001). In addition, the likelihood of developing distant metastasis is greater in the submandibular gland than the parotid (Schwenter et al. 2006); however, this may be due to the higher percentage of ACC. In one large series of 370 cases only 12 (3%) presented with distant metastases, but 24.9% were found to have positive regional nodes (Bhattacharyya 2004). Interestingly, in this retrospective review extrag-landular extension and nodal positivity did not affect survival. Goode, Auclair, and Ellis (1998) in a study of 234 cases of MEC of the major salivary glands stated that MECs with equal histopathologic grade had a better prognosis when their tumors were in the parotid gland rather than in the sub-mandibular gland. This finding was confirmed in a Swedish study of 2,465 major salivary gland tumors (Wahlberg, Anderson, and Bjorklund et al. 2002). High-grade MEC is also more common in the submandibular gland, with 32 of 82 cases (39%) occurring in this gland (Bhattacharyya 2004).

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