下顎骨における歯原性嚢胞を伴う動脈瘤様骨嚢胞：診断上の課題-症例報告

Aneurysmal bone cysts (ABCs) are rare, benign, expansile lesions of the jaws, often associated with odontogenic cysts like dentigerous cysts, presenting diagnostic challenges due to their variable radiographic and histopathological features. This case report describes an ABC associated with a dentigerous cyst in the mandible, initially misdiagnosed as central giant cell granuloma (CGCG). A 19-year-old male presented with an asymptomatic semi-erupted right mandibular third molar (#48), and panoramic radiography revealed a multilocular radiolucent lesion (22.9 × 46.5 × 20.4 mm) in the posterior mandible and ascending ramus, with features including curved and coarse septa, hazy bone pattern, possible root resorption, mild cortical expansion on CBCT, focal perforation, and posterior displacement of the mandibular nerve canal. Initial incisional biopsy suggested CGCG due to multinucleated giant cells and fibrous stroma, but excisional biopsy confirmed an ABC with sinusoidal spaces alongside a dentigerous cyst lined by nonkeratinized stratified squamous epithelium. This case highlights the critical role of CBCT and excisional biopsy in diagnosing ABCs associated with dentigerous cysts, distinguishing them from CGCG and other lesions through integrated clinical, radiographic, and histopathological evaluation.