Alveolar rhabdomyosarcoma with multiple bone marrow infiltration

A 15-year-old girl visited Hunan Provincial People's Hospital (The First Affiliated Hospital of Hunan Normal University, Changsha, China) in November, 2022, because of a 13-day history of lower back and leg pain. She had no previous medical history. Her symptoms did not alleviate after treatment with intravenous fluids and analgesics in a local hospital. Abdominal tenderness and muscle spasm were detected on physical examination. Laboratory test results showed a white blood cell count of 14·03 × 109 per L (reference range 4–10 × 109 per L), a neutrophil count of 9·6 × 109 per L (reference range 1·3–8·3 × 109 per L), a monocyte count of 0·78 × 109 per L (reference range 0·14–0·6 × 109 per L), and a platelet count of 85 × 109 per L (reference range 100–300 × 109 per L). PET-CT scan showed extensive and diffuse bone marrow involvement and a hypermetabolic subcutaneous nodule in the chest wall (figure). Therefore, lymphoma was considered as the initial diagnosis.