Diagnostic approach for the rare anterior variant of mandibular bone depression often misdiagnosed as tumorous lesions

Background/purpose: This study analyzed the clinical and imaging features of lingual mandibular bone depression (LMBD) in the anterior mandible, aiming to prevent misdiagnosis and unnecessary surgical procedures. Materials and methods: The patients who visited a university dental hospital for painless radiolucency in the anterior mandible from January 2010 to December 2022 were retrospectively reviewed. Twelve cases of LMBD in the anterior mandible that are confirmed by biopsy or long-term follow-up were identified. Two oral and maxillofacial radiologists evaluated the imaging features. Additionally, 12 cases were manually collected from case reports published between 2001 and 2022. Clinical and histopathologic data were obtained from both groups and clinical information were compared using Fisher's exact test. Results: The clinical information of the patients and that from the case reports showed no statistically significant differences, except for the clinical impression (P = 0.005). The imaging features of anterior LMBD included the absence of lingual cortical expansion and soft tissue bulging, a mostly round cortical border, and muscle-level attenuation, as observed on multidetector computed tomography (MDCT). Occasionally, the progression of LMBD led to thinning of the labial cortex. Conclusion: If non-specific clinical features are present, MDCT is recommended to distinguish anterior LMBD from tumorous lesions that require surgical intervention.