Intraosseous Mucoepidermoid Carcinoma of the Anterior Mandible: A Case Report

Abstract

Intraosseous mucoepidermoid carcinoma (MEC) is a rare neoplasm, generally presenting in the posterior mandible and occurring in the 3rd-5th decade. This condition may mimic ameloblastoma both clinically and radiologically, with challenges in diagnosis. We present the case of a 51-year-old female who presented with a history of swelling over her jaw for one month. On examination, the mass involved the outer table of the mandible, from the right canine to the left first premolar. The swelling was hard, non-tender, with a nodular surface. A PET CT scan showed a multiloculated cystic lesion in the anterior mandible. An orthopantomogram (OPG) depicted a lytic lesion in the anterior mandible with outer table involvement and was suspected to be ameloblastoma. The patient underwent segmental mandibulectomy, neo-mandible reconstruction surgery with an osteomyocutaneous free fibular flap (from the right leg), and split skin grafting over the donor site. The patient recovered well. However, contrary to our suspected diagnosis, the final histopathological report showed features suggestive of mucoepidermoid carcinoma. Hence, mucoepidermoid carcinoma can be misdiagnosed as ameloblastoma due to similar clinico-radiological features. Histopathology is confirmatory and needs to be reviewed to confirm the diagnosis.

Keywords: ameloblastoma; mandibular tumor; mandibulectomy; misdiagnosis; mucoepidermoid carcinoma.

Figure 1. OPG X-ray showing multiloculated cystic lesion (red arrow) in the anterior mandible measuring 4.7 cm × 2.5 cm × 3.1 cm with no cortical breach

Figure 2. Images depicting the steps of surgery in tumor resection

(A) Tumor exploration, (B) segmental mandibulectomy, (C) surgical plating, and (D) surgical site closure

Figure 3. Images (A) and (B) depicting gross morphology of the resected tumor showing intraosseous cystic lesion. Note the septations within the cyst.

Figure 4. Patient presentation at follow-up after 3 months; A- Front view of the mandible, B- Lateral view of the mandible

Figure 5. Images (A) and (B) showing sections of mandible with overlying mucosa and an intraosseous cystic neoplasm

Figure 6. (A) Section showing neoplasm composed of varying mixture of pleomorphic squamoidal cells, intermediate cells, and mucinous cells forming glands; (B) section with Ki-67 immunostaining showing low proliferative index (<5%)