The imaging features are of an aggressive process with both infective (i.e. osteomyelitis) and tumor (e.g. gnathic osteosarcoma) within the differential diagnosis. Recent tooth extraction and smooth periosteal reaction favors osteomyelitis. The patient went on to bone biopsy. 

Histopathology

MACROSCOPIC DESCRIPTION: "Right posterior mandible": Four white and pink hard bony pieces of tissue between 5-10mm. Specimen placed in decal.

MICROSCOPIC DESCRIPTION: Sections show decalcified bony fragments composed of woven bone trabeculae with intervening marrow fibrosis. Osteoblastic rimming is present. The paucicellular fibrous tissue contains bland spindle cells. No mitoses are identified. Occasional aggregates of mononuclear chronic inflammatory cells are identified. No acute or granulomatous inflammation is seen. There is no evidence of atypia or malignancy. Immunohistochemical results confirm the presence of scattered CD138 positive chronic inflammatory cells (plasma cell morphology distorted by decalcification process).

DIAGNOSIS: Right posterior mandible, biopsy: Reactive woven bone with medullary fibrosis; no definite tumor seen.

COMMENT: The histological features are non-specific and no definite tumor is seen. The differential diagnosis includes chronic osteomyelitis. Clinical and radiological correlation is recommended.

A diagnosis of osteomyelitis was made based on clinical, radiological, and pathological evidence and the patient proceeded to a long-term course of antibiotics.