Two periosteal reactions

Correct answer: D. Chronic osteomyelitis with proliferative periostitis (Garré)

• A. Ewing sarcoma is the genuine mimic and deserves to be known, because it can also produce onion-skin periostitis. It is distinguished by PAIN, fever, raised inflammatory markers and a permeative, destructive lesion — none of which is present here, and all of which the stem deliberately excludes.
• B. Osteosarcoma also produces a periosteal reaction, but the classic pattern is SUNBURST or spiculated rather than layered, and it is accompanied by symmetrical widening of the periodontal ligament space. It also occurs in an older age group and would not be explained by a carious non-vital molar.
• C. Fibrous dysplasia produces ground-glass bone blending imperceptibly into normal bone, with no periosteal layering and no associated non-vital tooth.
• D. CORRECT. CHRONIC OSTEOMYELITIS WITH PROLIFERATIVE PERIOSTITIS, historically GARRÉ osteomyelitis, is a disease of CHILDREN AND YOUNG ADULTS, almost always at the LOWER BORDER OF THE MANDIBLE, driven by a low-grade infection — typically a carious non-vital first molar, exactly as here, or a pericoronitis. The periosteum responds by laying down successive parallel layers of new bone, producing the ONION-SKIN appearance. The management point is the important one: treat the SOURCE. Extract or root treat the offending tooth and the periosteal bone remodels over months without any need for surgery on the swelling itself.

Note: The lesson generalises: a periosteal reaction is a pattern, not a diagnosis. ONION-SKIN in a child with a carious tooth → proliferative periostitis. ONION-SKIN with pain and fever → exclude Ewing sarcoma. SUNBURST with widened PDL spaces → osteosarcoma until proven otherwise.

Correct answer: C. Chondrosarcoma produces a malignant CARTILAGINOUS matrix and favours the ANTERIOR MAXILLA, while osteosarcoma produces malignant OSTEOID and more often affects the mandible

• A. The age relationship is the reverse of this. Chondrosarcoma is a tumour of ADULTS, typically the third to sixth decades. It is OSTEOSARCOMA that has a peak in adolescents and young adults, alongside a second peak in older patients with Paget disease or prior irradiation.
• B. Both are relatively RADIORESISTANT, and chondrosarcoma is notably poorly responsive to both radiotherapy and chemotherapy. That is precisely why WIDE SURGICAL RESECTION with clear margins is the mainstay of treatment and why margin status dominates the prognosis.
• C. CORRECT. The defining difference is the MATRIX the malignant cells produce — chondroid in chondrosarcoma, OSTEOID in osteosarcoma — and that histological criterion is what separates them, since their radiographic appearances overlap substantially. In the jaws, chondrosarcoma favours the ANTERIOR MAXILLA, along with the nasal septum and the condylar and coronoid regions, while osteosarcoma more often affects the MANDIBLE. Both can show a mixed radiolucent-radiopaque pattern, a sunburst reaction, and SYMMETRICAL WIDENING of the periodontal ligament space — that last sign being a red flag for either.
• D. A sunburst periosteal pattern can occur in EITHER tumour, which is exactly why the radiograph alone does not settle the diagnosis and biopsy does.

Note: Symmetrically widened periodontal ligament spaces around several teeth is a finding that should never be dismissed. The differential is short and serious: osteosarcoma, chondrosarcoma, and SCLERODERMA — which is not malignant but is systemic and produces the same appearance through collagen deposition.