Benefits of maxillectomy with internal dissection of the masticator space by transmandibular approach in the surgical management of malignant tumours of the upper gingiva and hard palate: a clinical review of 10 cases

Abstract

The aim of this study was to review patients with tumours extending to the posterior portion of the upper gingiva and hard palate, and to evaluate the postoperative outcomes. Ten consecutive patients with tumours in the upper gingiva and hard palate, who underwent maxillectomy with internal dissection of the masticator space by the transmandibular approach, were reviewed retrospectively. Among the 10 patients, the pathological diagnosis was squamous cell carcinoma in seven, adenoid cystic carcinoma in one, malignant melanoma in one, and osteosarcoma in one. Loco-regional control was achieved in eight of nine patients (88.9%). Three patients had residual moderate trismus. Cosmetic issues were not noted in any patient. En bloc resection of the maxilla with the internal portion of the masticator space and neck through the parapharyngeal space by the transmandibular approach is a useful and satisfactory technique for the excision of a tumour with involvement of the posterior portion of the upper gingiva and hard palate.

Oral cancer represents about 1–3% of all human cancers, and is the sixth most frequent cancer worldwide. Oral cancer continues to show a poor prognosis and remains a lethal disease for more than 50% of cases diagnosed annually. Ten percent of all oral cancers occur in the oral cavity subsites of the upper gingiva and hard palate. Oral cancers of the upper gingiva and hard palate often have similar clinical presentations and management because of their adjacent anatomies; however the relative rarity of these cancers compared to those at other primary sites has resulted in only small case series lacking survival or other outcome analyses.

Several reports have revealed that patients with a tumour extending to the retromaxillary region, oropharyngeal soft palate, or infratemporal fossa have poor survival outcomes. One of the reasons for the poor prognosis in these cases is thought to be recurrence in the parapharyngeal space or the masticator space. Some lymph vessels of the maxilla are known to pass through the parapharyngeal space and flow out into the upper jugular lymph nodes. Therefore, in previous reports we have suggested the necessity of en bloc resection of the maxilla and neck through the parapharyngeal space by the transmandibular approach in patients with a tumour that extends to the retromaxillary region. Moreover, the masticator compartment of the infratemporal fossa is an obvious source of local recurrence in maxillary malignant tumours with posterior extension to the infratemporal fossa.

Anatomically, the masticator space is delineated by the superficial layer of the deep cervical fascia. At the base of the mandible, the superficial layer of the deep cervical fascia splits into two layers. The outer layer encloses the masseter muscle, extends over the zygomatic arch, and attaches to the temporalis muscle and the lateral orbital wall. The inner layer extends deep into the medial pterygoid muscle and attaches to the skull base medial to the foramen ovale ( Fig. 1 A ). These two layers fuse along the anterior and posterior borders of the mandibular ramus, enveloping the space. This space includes the mandibular nerve and its branches, internal maxillary artery and its branches, adipose tissue, and masticatory muscles ( Fig. 1 B).

Fig. 1
Anatomy of the masticator space. (A) Coronal line diagram showing the superficial layer of the deep cervical fascia splitting into two layers at the base of the mandible. The outer layer (labelled 1) encloses the masseter muscle, extends over the zygomatic arch, and attaches to the temporalis muscle and the lateral orbital wall. The inner layer (labelled 2) extends deep to the medial pterygoid muscle and attaches to the skull base medial to the foramen ovale. (B) Axial line diagram showing the outer and inner layers fusing along the anterior and posterior borders of the mandibular ramus and enveloping the space. The masticator space includes the mandibular nerve and its branches, internal maxillary artery and its branches, adipose tissue, and masticatory muscles. Note the close relationship of the masticator space to the pre-styloid parapharyngeal space (black dots) medially. MP, medial pterygoid muscle; M, masseter muscle; LP, lateral pterygoid muscle; T, temporalis muscle; FO, foramen ovale; P, parotid gland; ECAR, external carotid artery; ICAR, internal carotid artery; JUG, jugular vein; STY, styloid process.

Oral cancer adjacent to the masticator space can deeply invade the masticator space components simply because of the anatomic vicinity, and is staged as T4b. At this site, surgical resection using a conventional approach is often difficult, resulting in unsatisfactory survival. In particular, a tumour with involvement of the posterior portion of the upper gingiva and hard palate sometimes relapses at the infratemporal fossa in the internal portion of the masticator space. In such cases, some authors have reported the transmandibular approach to be an effective technique for maxillectomy with internal dissection of the masticator space.

The aim of this study was to review our patients who had undergone a maxillectomy with internal dissection of the masticator space by the transmandibular approach and to evaluate the postoperative outcomes.

Patients and methods

Patients

From 2004 to 2012, 10 consecutive patients with involvement of the posterior portion of the upper gingiva and hard palate ( Fig. 2 ), underwent maxillectomy with internal dissection of the masticator space by the transmandibular approach; these patients were reviewed retrospectively ( Table 1 ). Staging was performed using clinical data recorded at the time of initial assessment of each patient according to the TNM classification system of the American Joint Committee on Cancer (AJCC), sixth edition.

Fig. 2
Computed tomography image showing a tumour extending to the posterior portion of the upper gingiva and hard palate, pterygoid plates, and masticator space.

Table 1
Demographic characteristics and treatment summaries of 10 patients undergoing en bloc resection of the maxilla with the internal portion of the masticator space and neck through the parapharyngeal space by transmandibular approach.
Patient Age, gender Site Pathological diagnosis (TN stage) Procedure Reconstruction Survival
1 37, F Hard palate Adenoid cystic carcinoma (T4bN0) Maxillectomy + SND Radial forearm free flap Alive 10 years with lung metastasis
2 52, M Maxillary gingiva Squamous cell carcinoma (T4bN1) Maxillectomy + mRND No reconstruction Alive without evidence of disease after 9.5 years
3 52, M Maxillary gingiva Squamous cell carcinoma (T4bN1) Maxillectomy + mRND Radial forearm free flap Alive without evidence of disease after 8.5 years
4 72, M Maxillary gingiva Squamous cell carcinoma (T4bN2c) Maxillectomy + bilateral mRND Radial forearm free flap Died of pneumonia after 3 months
5 76, F Maxillary gingiva Squamous cell carcinoma (T4bN2b) Maxillectomy + mRND → PORT Radial forearm free flap Alive without evidence of disease after 6.5 years
6 82, M Maxillary gingiva Squamous cell carcinoma (T4bN2b) Maxillectomy + mRND → PORT Radial forearm free flap Alive without evidence of disease after 4.5 years
7 63, M Hard palate Malignant melanoma (T4bN1) Maxillectomy + mRND Rectus abdominis flap Died of neck recurrence after 10 months
8 77, M Hard palate Osteosarcoma (T4bN0) Maxillectomy + SND No reconstruction Alive without evidence of disease after 2.5 years
9 78, M Maxillary gingiva Squamous cell carcinoma (T4bN1) Maxillectomy + mRND Pectoralis major myocutaneous flap Alive without evidence of disease after 2.5 years
10 78, F Maxillary gingiva Squamous cell carcinoma (T4bN0) Maxillectomy + SOHND Radial forearm free flap Alive without evidence of disease after 2 years
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Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Benefits of maxillectomy with internal dissection of the masticator space by transmandibular approach in the surgical management of malignant tumours of the upper gingiva and hard palate: a clinical review of 10 cases
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