AKT-5050

A 13-year-old girl is brought to the GP by her father. She has been experiencing pain in her left leg which feels like it is originating from her bone just below her knee. She reports that the pain has been present for a few weeks and is persistent and achy, frequently worsening at night. During the examination, a bony lump is observed on her tibia, just below her knee joint. What investigation should this child be referred for within 48 hours?