Intraosseous mucoepidermoid carcinoma of the mandible

Abstract

Background: Mucoepidermoid carcinoma starts in the salivary glands and accounts for 5%-10% of all salivary gland tumours. Its intraosseous occurrence is rare and only accounts for 2%-3% of all mucoepidermoid carcinomas. This neoplasm often follows a long and indolent course. Also, given its ambiguous presentation and similarities to other dental pathologies, it often has a late diagnosis. In this instance, we present the case of a patient with an asymptomatic mandibular lesion, who underwent mandibular resection and reconstruction with fibula free flap.

Case report: A 32-year-old male patient reported discomfort when chewing, which was attributable to a self-detected mass localised in proximity to teeth 47 and 48. The lesion presented as a slight swelling without clear expression in the oral cavity mucosa. The rest of the physical examination revealed no abnormalities. Both the panoramic radiograph and computed tomography of the maxillary bones revealed lytic lesions in proximity to teeth 47 and 48, close to the mandibular angle. An incisional biopsy was performed, for which the pathological anatomy showed low-grade mucoepidermoid carcinoma. A resection was then performed, which involved a right hemimandibulectomy with ipsilateral cervical lymphadenectomy. The reconstruction was performed with a right fibula-free flap. Upon histological evaluation of the surgical specimen, an intermediate-grade mucoepidermoid carcinoma was found. The patient presented good post-operative evolution. Following a multidisciplinary assessment, the use of adjuvant radiation therapy was deemed necessary. The patient currently presents good evolution and has regular check-ups.

Conclusion: Intraosseous mucoepidermoid carcinoma is a rare salivary gland tumour. Given its low frequency, there are no studies that accurately describe its biological behaviour and prognosis.

Keywords: intraosseous lesions; mandibular neoplasms; mucoepidermoid carcinoma; salivary glands.

Figure 1.. Panoramic radiograph of the maxillary. A radiolucent cystic and osteolytic lesion localised in the retromolar trigone can be seen in proximity to teeth 47 and 48.

Figure 2.. CT with intravenous contrast. Both the soft tissue window (a) and bone windows (b–c), shows an osteolytic lesion with right mandibular body and ramus involvement, localised in the retromolar space behind tooth number 48. The lesion features soft tissue components and presents lingual cortical disruption. It shows the involvement of the adjacent inferior alveolar nerve canal. It measures approximately 29 × 23 × 11 mm in size.

Figure 3.. 3D Stereo-lithographic planning. (a) Lesion in red in relation to the inferior alveolar nerve and teeth. Cutting guides with adequate oncological margins and prefabricated angulation for their subsequent reconstruction were provided. (b and c) Cutting lines made on the right fibula for the incorporation of bone fragments, an accurate subsequent osteosynthesis and reconstruction of the new mandible.

Figure 4.. (a) Layout established for the free fibula flap approach. (b) Resected fibular fragment alongside the peroneal muscle and vascular bundle. The bone fragments were moulded and fixed to the titanium reconstruction plate. (c) Highlights the anastomosis of the peroneal veins to the facial artery, the external jugular vein, and the facial vein. It also shows its fixation to the remaining right mandible using a titanium reconstruction plate.

Figure 5.. Histopathology. Haematoxylin and eosin stain (10×). (a) Atypical epithelial proliferation consisting of mucinous, intermediate and squamous cells. The cells described form solid nests that line glandular spaces, some with cystic dilations and extracellular mucin. (b and c) Epithelial proliferation with similar characteristics and active compact bone tissue involvement.

Figure 6.. Second post-operative month. Both figures (a) and (b) show the correct lateral and anterior projection of the reconstructed mandible. The patient has on-going masticatory function rehabilitation exercises.