A Case of Focal Osteoporotic Bone Marrow Defect of the Mandible

Abstract

Focal osteoporotic bone marrow defect （FOBMD） is a rare benign jaw lesion consisting of hematopoietic bone marrow, which results in a focal bone defect. The present report describes a case of FOBMD in the mandibular molar region of a male in his 70s. A panoramic radiograph showed the presence of an undefined round, thumb-sized radiolucent lesion in the left mandible. CT and MR images suggested a clinical diagnosis of primary intraosseous lipoma. The surgical specimen was a yellow soft-elastic fat tissue, and it was difficult to histopathologically distinguish focal osteoporotic bone marrow defects from primary intraosseous lipoma. However, the definitive diagnosis of FOBMD was established on the basis of the histopathological findings of remaining hematopoietic marrow and no capsule formation. The postoperative clinical course has been uneventful for 2 years.