A 10-year-old girl presents with fever, anaemia, leukocytosis, and a painful swelling of the mid-shaft of the femur. X-ray shows an onion-skin periosteal reaction. Biopsy shows small round blue cells with little cytoplasm in sheets. The diagnosis is:

• A Osteosarcoma
• B Osteomyelitis
• C Metastatic neuroblastoma
• D Ewing's sarcoma ✓

Explanation

Ewing's sarcoma is the second most common primary malignant bone tumour in children and adolescents. It characteristically involves the diaphysis of long bones and flat bones. The clinical picture mimics infection (fever, raised ESR, leukocytosis), and the onion-peel periosteal reaction on X-ray is classic. Histologically it shows small round blue cells with scanty cytoplasm; PAS-positive glycogen granules are present. The t(11;22) translocation is pathognomonic.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.