Massive osteolysis of the mandible.

This report deals with a massive osteolysis, which is a rare disease characterized by the progressive dissolution of contiguous osseous structure, occurring in the mandible of a 46-year-old Japanese female. Histopathologic examination of the amputation material revealed that the mandibular body, ramus, condylar and coronoid processes were completely replaced by fibrous tissue, but inferior alveolar nerve and artery in the lesion were intact. A few small islands of osteoid tissue or immature fibrous bone were seen in the lesion. In the transitional area between the lesion and normal bone, active absorption of bone trabeculae was in progress and intertrabecular spaces were occupied by densely packed fibroblastic cells, however, angiomatous proliferation of vessels was not observed. A few bone trabeculae were surrounded by osteoclasts, but osteoclasts might not play a primary etiological role in massive osteolysis.