An Unusual Case of Back Pain in a Healthy Soccer Player

A previously healthy 11-year-old girl presents to a pediatric emergency department located in the mid-Atlantic region with 4 days of worsening lower back pain and 3 days of fever with a maximum temperature of 101°F. She describes her pain as constant and achy, rating it an 8/10 in severity. The pain is worsened by lying flat and extends from the lumbar spinal region toward the sacrum. She denies difficulty walking or recent trauma; however, she plays soccer and has multiple bruises. She denies numbness, tingling, bowel habit changes, or problems urinating. She has tried heat packs and acetaminophen/ibuprofen, which have provided some relief. Her history is notable for a tick bite 3 weeks ago, which was embedded in her skin and removed.On admission, her vital signs are as follows: temperature, 99.1°F; heart rate, 105 beats/min; respiratory rate, 20 breaths/min; and blood pressure, 118/60 mm Hg. Her physical examination is notable for a petechial rash on her right inner thigh and bilateral shins, with right-knee bruising and tenderness to palpation on lumbar paraspinal muscles with no bony spinal tenderness.Her initial laboratory evaluation reveals a normal white blood cell (WBC) count of 885 000/mm3, hemoglobin level of 11.5 g/dL, and thrombocytopenia with platelet count of 53 000/mm3. Her complete blood count differential (CBC) test reveals 60% neutrophils with an absolute neutrophil count of 595 000/mm3, 6.0% bands, 25% lymphocytes with absolute lymphocyte count of 2300/mm3, 2% monocytes, and 3% metamyelocytes. She has elevated inflammatory markers with an erythrocyte sedimentation rate of 91 mm/h (range, 4–25 mm/h), ferritin level of 1131 ng/mL (range, 13–150 ng/mL), and C-reactive protein (CRP) level of 21 mg/dL (range, 5% chance) of developing TLS. Aggressive fluid hydration is essential for management of TLS to improve renal blood flow and excretion of potassium and uric acid, while allopurinol is used to prevent the formation of uric acid.22–24Our patient began induction chemotherapy with intrathecal cytarabine, steroids, vincristine, dexrazoxane, daunorubicin, and pegaspargase. Her pain subsequently improved, and oxycodone was discontinued. TLS laboratory test results were monitored closely, and allopurinol was discontinued because uric acid and electrolyte levels were normal. Given her CNS involvement, she required additional doses of intrathecal chemotherapy on days 4, 8, and 10 of induction. Cerebrospinal fluid studies showed no evidence of CNS leukemia during this time. On day 29, bone marrow aspiration and flow cytometry were performed for surveillance of leukemia, revealing hypocellular marrow with no evidence of residual leukemia. Our patient has now completed consolidation, interim maintenance, and delayed intensification chemotherapy, with each stage lasting 6 to 8 weeks. Our patient is currently receiving maintenance chemotherapy, which she will continue for the next year.Back pain is a common symptom seen in the adolescent population, with common differential diagnoses including muscle sprain, trauma, spondylolisthesis, or scoliosis.Red-flag symptoms of back pain include focal point tenderness, pain associated with abnormal neurological examination findings, nightly pain that awakens the patient from sleep, and pain that is associated with constitutional symptoms.Risk stratification is the first step toward determining prognosis for patients with ALL. Individuals with high-risk ALL are usually at least 10 years old and have a WBC count greater than 50 × 109 cells/L or may have CNS or testicular involvement.