[A radiolucent rarity - primary intraosseous mucoepidermoid carcinoma of the posterior mandible: From radiographic incidental finding to molecular pathological diagnosis]. / Eine radioluzente Rarität ­ Primär intraossäres Mukoepidermoidkarzinom des posterioren Unterkiefers: vom röntgenologischen Zufallsbefund zur molekularpathologischen Diagnose.

We report the case of a 64-year-old patient with incidental finding of a unilocular radiolucency in the posterior mandible on an apical radiograph. The biopsy (cystostomy) revealed the unusual finding of a primary intraosseous mucoepidermoid carcinoma; this is with 2­4% of ectopic manifestations of this entity a rarity. Molecular pathological analysis with a specific panel (SalvGlandDx) and FISH provided diagnosis-confirming evidence of the specific CRTC1-MAML2 fusion. Box resection, prophylactic osteosynthesis using a patient-specific reconstruction plate, neck dissection, and local coverage using a Bichat flap were performed according to the interdisciplinary tumor board decision. With tumor-free lymph nodes and R0 resection, adjuvant therapy was not required. Clinical and imaging follow-up over 24 months showed no evidence of locoregional recurrence. The presented case report emphasizes the central role of private dental practices in the early detection of oral malignancies. These should always be considered in the differential diagnosis of cystic lesions.