PÁGINA DEL RESIDENTE

 

What would be your diagnosis and treatment plan?

¿Cuál sería su diagnóstico y abordaje quirúrgico?

 

 

A 51 year-old female, ex-smoker of one packet of cigarettes a day for 25 years, with a background of breast fibroadenoma, attended our department as she was suffering from aphonia and slight dysphagia that had been evolving for 5 months. As the oral examination was normal, an examination by fiberscope was carried out that revealed an exophytic mass measuring 4x3 cm at the base of the tongue on the right side that reached the lateral wall of the pharynx, the right tonsil-palatoglossal fold and the epiglottic vallecula.

The cervicofacial computed tomography (CT scan) reported a mass in the soft tissue with a diameter of 3 cm on the right oropharyngeal wall. It was affecting the tonsils and it was extending forward to the base of the tongue and floor of the mouth. The mass protruded towards the pharynx lumen, stretching back to the parapharyngeal space that appeared partially obliterated. The most caudal portion of the mass reached the level of the valleculae and it was invading the glosso-epiglottic fold. The most likely diagnosis was thought to be epidermoid carcinoma. Swollen lymph nodes of less than 1 cm were in both the submandibular and jugular-digastric chains. They were insignificant radiologically but neoplastic infiltration could not be ruled out (Fig. 1).

Nuclear magnetic resonance (NMR) showed a mass with a 3.5 cm diameter that was polylobulated and at the base of the tongue. It was extending towards the floor of the mouth from the posterior third. Laterally, it was attached to the right lateral wall of the oropharynx, including the tonsillar fossa and the anterior and posterior tonsillar pillars. It reached back to the digastric muscle. Caudally it extended along the base of the tongue to the valleculae, to the right vallecula in particular and the glosso-epiglottic fold, leaving the left vallecula unaffected. The signal was intermediate on the T1-weighted sequences, and there was a larger hypersignal on the T2-weighted sequences with heterogeneous areas in the center of greater intensity when compared to areas of cystic-necrotic degeneration. The administration of gadolinium showed an intense and uniform contrast enhancement. The presumed diagnosis was of epidermoid carcinoma.

The gammagraphy with ¹³¹I ruled out the existence of lingual thyroid. The biopsy of the lesion revealed a non-keratinized squamous epithelium with foci of lymphoid tissue by the chorion, and atypical cell infiltrate, with abundant cytoplasm and nuclei of various shapes and sizes, and prominent nucleoli. The PAS technique showed some positive cells. The immunohistochemical analysis was positive for keratins AE-1 and AE-3 and negative for S-100 and GFAP.

 

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Mucoepidermoid carcinoma of the base of the tongue. A surgical approach by means of the median labiomandibulotomy

Carcinoma mucoepidermoide de base de lengua. Abordaje quirúrgico mediante labiomandibulotomía media

 

 

R. González-García¹, J. Sastre Pérez², V. Escorial Hernández¹, P.L. Martos¹, M. Mancha de la Plata¹, 
F.J. Rodríguez Campo², L. Naval Gías², S. Nieto Llanos³, F.J. Díaz González⁴

1 Médico Residente
2 Médico Adjunto
4 Jefe de Servicio
Servicio de Cirugía Oral y Maxilofacial
3 Médico Adjunto de Anatomía Patológica
Servicio de Anatomía Patológica
Hospital Universitario La Princesa, Madrid. España.

Dirección para correspondencia

 

 

Following the initial histological diagnosis of adenocarcinoma and of stage III tumor (T3NoMx), and as there was a possibility of having to included the epiglottis and all of the larynx in the surgical resection, the Head and Neck Tumor Committee decided on first administering radiochemotherapy. Al-Sarraf type chemotherapy was started followed by a concomitant dose of CDDP of 100 mg/m². The radiotherapy treatment consisted in the administration of 50 Gy in fractions. During the combined radiochemotherapy her general health deteriorated. She was hospitalized by the emergency services with nausea and vomiting. A general blood test showed a level of creatine of 2, and nephrotoxicity was diagnosed secondary to cisplatin together with gastrointestinal toxicity secondary to the combined radiochemotherapy. Grade III mucositis was observed in the head and neck. As there was no improvement in the tumor either clinically or radiologically two weeks after starting the treatment, the therapy was suspended and the surgical option was decided upon.

Under general anesthesia with nasotracheal intubation, and following functional neck dissection on the right side, the mandibular symphysis was exposed by means of a vertical cutaneous incision. The neck incision was continued to the lip midline and a midline lip splitting incision was then performed. An incision was made into the periosteum, and it was detached just enough to allow placing the osteosynthesis material. Three four hole non-bridging miniplates were then adapted, and the ones for the ends were placed below the apex and at the base of the mandible. Fixation was carried out with 7 mm screws. The miniplates were then fixed, the fixtures were released at one end and the mandibular osteotomy was carried out with a reciprocating saw under continuous saline irrigation. A median glossotomy was then carried out, and the mucosa and muscles of the floor of the mouth were sectioned. The tumor mass was resected with macroscopically healthy margins. It appeared to have a pedicle, as it was attached by a narrow base, and the epiglottis and larynx were preserved. The intraoperative pathologic examination reported a tumor mass with no infiltration of the margins. The defect was repaired by means of direct closure, and neither regional nor microvascularized free flaps were needed. Following closure of the median glossotomy and of the floor of the mouth layers following the incision with resorbable sutures, the mandibular segments were joined and fixed with the miniplates, and the screws that had previously been removed were inserted. The skin was sutured with 4-0 monofilament material. (Fig. 2)

The macroscopic examination revealed a whitish exophytic tumor measuring 3.3 cm in diameter, that was well-circumscribed microscopically and that did not extend to the resection margins. It was made up largely of intermediate sized cells that had slightly irregular nuclei, prominent nucleoli and clear cytoplasm. Other areas of the tumor cellularity had scant cytoplasm and a squamous pattern, and there were areas of very isolated glandular structures in which mucinous cells could be identified. The tumoral cells were arranged in irregular nest shapes or thick cords in stroma with abundant fibroblasts and areas with a myxoid appearance, and in some areas there were cystic structures that made up less than 20% of the tumor, but neither necrosis nor nuclear anaplasia were observed. Isolated perineural invasion was observed focally. The mitotic index was less than 4 mitoses per 10 high power fields. The tumor was situated on the chorion of the tongue, but at no point did it continue to the epithelium or lining of the tongue. The definitive pathologic diagnosis was of low-grade mucoepidermoid carcinoma of the minor salivary glands at the base of the tongue (Fig. 3). The neck nodes were negative for metastatic infiltration. Radiation therapy treatment was subsequently administered.

 

Discussion

Although a rare entity, the mucoepidermoid carcinoma (MEC) together with the cystic adenoid carcinoma, represents the most common malignant tumor of the salivary glands. It affects mainly adults during the fourth and sixth decades in life. MEC affects the major and minor salivary glands equally, although low-grade MEC is more frequently found in the minor salivary glands. Although more common in the minor salivary glands of the mouth, it has been reported that in 10% of patients it can appear in the maxillary sinuses, nasopharynx, nasal cavity, oropharynx, vocal cords, larynx and trachea.^1,2 With regard to this case, and given the localization in the oropharynx and base of the tongue, the differential diagnosis should be carried out with other entities such as the thyroglossal duct cyst, lingual thyroid, hyperplastic lymphoid tissue, lymphangioma, fibroma, lipoma, dermoid cyst, squamous cell carcinoma, lymphoma and other minor salivary gland tumors.³

With regard to prognosis, Plambeck et al.⁴ described global survival rates of 91,9 and 89,5% at 5 and 10 years. This rate fell to 63,5 and 52,0% at 5 and 10 years in patients with stage III and IV. The presumed diagnosis, based on the initial biopsy was of adenocarcinoma of minor salivary gland origin. Both imaging studies showed nodal enlargement of not more than 1 cm in the submandibular and jugular-digastric chains. Sheahan et al.⁵ reported a percentage of occult neck metastasis (N0 necks) of 40%, and that CT and NMR were not useful for detecting occult neck disease. They concluded that neck dissection is indicated for patients with highgrade salivary gland adenocarcinoma of the head and neck. As a result of this information, homolateral functional neck dissection was carried out. This proved to be the right decision following the definitive histological diagnosis of MEC. With regard to tumor size, neck dissection for T2 MEC and above has quite rightly been indicated as a necessary requirement given the potential risk of regional metastasis.⁶ Clinical stage and tumor grade have been reported as the most important prognostic factors in MEC. Other elements have been demonstrated as being independent prognostic factors: being above the age of 40, fixed tumors, T stage, N stage and histological grade.⁷ The existence of disease-free surgical margins represents in itself a prognostic factor for these tumors, and obtaining wide surgical exposure is essential for obtaining these margins. Given the oropharyngeal localization, this particular case required a surgical approach using a median labiomandibulotomy.

The labiomandibulotomy was first described in 1836 by Roux⁸ and it was re-introduced in 1929 by Trotter⁹ who extended the approach of his predecessor by means of a median translingual pharyngotomy. Since it was first described, the median mandibulotomy has been modified several times, especially the osteotomy technique and posterior fixation. In 1961 the median labiomandibular glossotomy was popularized by Hayes Martin,¹⁰ and Cohen et al¹¹ described the modification of the mandibular osteotomy line by means of creating a midline step and by extracting a central incisor.

The median labiomandibulotomy has been reported in the treatment for tumors of the oral cavity, oropharynx, parapharyngeal space, as it permits obtaining wide-field exposure. In a previous study by our group¹² this technique was analyzed in 21 patients that had epidermoid carcinoma (18) of the mobile tongue (4.7%), base of the tongue (38.1%), floor of the mouth (9.5%), oropharynx (33.3%) and clivus (14.2%). In this previous series, mucoepidermoid carcinoma was not diagnosed in any of the cases. In all the cases there was adequate exposure of the tumor, 2 patients suffered suture dehiscence with orocervical communication, 1 suffered osteoradionecrosis of the fracture line, 3 suffered infection of the osteotomy bed, and 2 had occlusal alterations. With regard to this series, other surgical options can be considered, such as a pull-through glossectomy for approaching tumors with a lingual or floor of the mouth localization. This would avoid osteotomies and lip-splitting techniques while ensuring proper tumor control.^13,14 It is our opinion that the surgical access for tumors situated at the base of the tongue and oropharynx is difficult, and the most important limiting factor is the mandible. The lack of adequate exposure can condition obtaining wide surgical margins. In these cases the transmandibular approach is suitable. With regard to our case, this technique was advisable given the posterior location of the tumor. The pedicled nature of the tumor could not be confirmed by the previous imaging studies, and as there was a possibility that there was considerable infiltration of the base of the tongue and oropharynx by the mass, with extension to the contralateral side and possible damage to laryngeal structures, an approach that allowed wide exposure was chosen.

Other techniques used for approaching tumors located in the oral cavity and oropharynx are the transhyoid pharyngotomy, lateral pharyngotomy and various forms of mandibulotomies. Mandibulotomies may be posterior to the mental foramen, lateral, anterior or midline. The latter can be subdivided into mandibulotomies of the midline or symphyseal, with the osteotomy line running between the two central incisors, and parasymphyseal with the line running between the lateral incisor and the canine tooth. In a comparative study between these two types of midline mandibulotomies, Dai et al¹⁵ did not find any differences that were statistically significant although, from a theoretical point of view, they advocated the midline parasymphyseal mandibulotomy as the insertions of the geniohyoid and genioglossal muscles were preserved and there were better results with regard to post-surgical sucking and swallowing function.

The global complication rate reported in the literature is around 20%, and this generally consists in occlusion disturbances, disorders relating to sensitivity in the area innervated by the lower dental nerve, temporomandibular joint pain, periodontal problems, wound infection and aesthetic changes due to the lip-splitting procedure. In an attempt at reducing the rate of complications with regard to periodontal disease, Bertrand et al¹⁶ proposed making a mucosal incision that was two to three teeth away from the area of the osteotomy, and that the mucosal closure should be carried out with transpapillary sutures and as hermetically as possible. These same authors reported unfavorable aesthetic results in 10% of cases, a rate that was higher than those of our group.^12,15 The removal of a central incisor has been proposed so as not to damage both adjacent roots as a result of the osteotomy, and to reduce the risk of periodontal disturbances. However, this procedure could lead to occlusal problems later on, and aesthetically this would be worse for the patient. We prefer not to perform any extractions at all, unless these is considerable periodontal disease. The use of fine saw blades and a fine chisel by the interdental space of the alveolar crest permits obtaining a clean cut, with a minimal amount of bone loss between the teeth, and the risk of periodontal disturbances is reduced.

With regard to mandibular osteosynthesis, the fixation procedures using wires have been replaced progressively with rigid fixation and mandibular compression plates, or semirigid fixation with miniplates, in order to reduce the rate of occlusion complications and those derived from the instability of the fracture site, such as infection and radionecrosis. All the cases in our series were treated by means of fixation with miniplates, with no evidence of pseudoarthrosis or consolidation delays. No complications were observed in the case presented six months after the surgery with regard to the osteotomy, in spite of the pre-operative radiochemotherapy and the post-operative adjuvant radiotherapy. In this sense, various authors^6,17,18 have not found a statistically significant correlation between radiotherapy and complications at the fracture site. Moreover Eisen et al¹⁹ compared the complications that appeared in patients who received postoperative radiation therapy to the osteotomy site, with the fracture sites of other patients that were shielded. Statistically significant differences were not found with moderate doses of radiation therapy.

Following the surgery, airway control is fundamental, precisely because of the location of these tumors. Carrying out a tracheostomy was obviated as the patient was kept under anesthesia and with nasotracheal intubation and connected to a respirator for 72 hours. Had the approach been carried out at the back of the floor of the mouth, ipsilateral to the lesion, the post-surgical risk of airway compromise would have been reduced. In our experience, the complication rate from orocervical fistulae as a result of this technique is greater than with a median glossotomy.

To conclude, the median labiomandibulotomy is an optimal approach for treating tumors of the oropharyngeal area and the parapharyngeal space, such as MEC, that provides an adequate surgical field enabling tumor excision with wide margins. The use of miniplates allows stable fixation of the mandibular osteotomy, with very few complications.

 

 

Dirección para correspondencia:
Raúl González García
C/ Los Yébenes 35, 8ºC
28047 Madrid, España.
raugg@mixmail.com

 

 

References

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