A round blue cell tumor found in the jaw or bone of a young patient is most consistent with which diagnosis?

Correct answer: A. Ewing sarcoma

• A. CORRECT — Ewing sarcoma is a malignant round blue cell tumor of bone typically occurring in children and young adults. Histologically, it consists of sheets of small, round, uniform blue cells. It most commonly affects long bones but can occur in the jaw.
• B. INCORRECT — Multiple myeloma is also a round cell malignancy (plasma cell tumor) but occurs in older adults and presents differently (punched-out radiolucencies, Bence Jones protein).
• C. INCORRECT — Osteosarcoma has a classic 'sun-burst' pattern radiographically and histologically shows malignant osteoid production, not round blue cell morphology.
• D. INCORRECT — Neuroblastoma is a round blue cell tumor but arises from the adrenal medulla or sympathetic chain, not typically primary bone/jaw.