A patient reports a tingling sensation in the lower lip. Examination shows a painless, indurated swelling in the premolar region. A radiograph shows loss of the cortical border and a diffuse, radiating pattern of trabeculae within the lesion. What is the most likely diagnosis?

Correct answer: C. Osteosarcoma

• A. A dentigerous cyst is a well-corticated, EXPANSILE pericoronal radiolucency around the crown of an unerupted tooth. It displaces rather than destroys, and it does not cause paraesthesia.
• B. Hyperparathyroidism produces generalised loss of lamina dura, a ground-glass trabecular pattern and multilocular brown tumors, accompanied by raised serum calcium and PTH — not sun-ray spiculation or focal lip paraesthesia.
• C. CORRECT. Three findings together point to OSTEOSARCOMA. First, PARAESTHESIA of the lip (Vincent sign) indicates a lesion invading and compressing the inferior alveolar nerve — a red flag for malignancy. Second, a firm, INDURATED, painless swelling with cortical destruction indicates infiltrative growth rather than expansion. Third, the radiating 'SUN-RAY' or 'sun-burst' spiculation of periosteal new bone is the classic radiographic sign, often with symmetrical widening of the periodontal ligament space around involved teeth (Garrington sign).
• D. Ossifying fibroma is a benign, well-demarcated, often encapsulated lesion that displaces roots and expands the cortex smoothly. It has a defined border, no cortical destruction and no paraesthesia.

Note: PARAESTHESIA with a jaw lesion in the absence of trauma or recent surgery is a malignancy sign until proven otherwise — the differential is osteosarcoma, metastatic carcinoma, lymphoma, multiple myeloma and osteomyelitis. Investigate promptly with imaging and biopsy.