A 9-year-old girl with ankle, knee, and shoulder pain.

History of the present illness This patient was in good health until September 2009, when she fell while running. At that time she felt a “pop” and developed right ankle pain followed by limping. Two weeks after the injury she went to her primary care physician, who obtained radiographs of her ankle, which were normal per the family. The patient continued to have right ankle pain and subsequently developed right knee pain. In November 2009 she was evaluated by an orthopedist and reported a temperature of 100.2°F the previous week. On examination she was noted to have an antalgic gait favoring the right side, right ankle swelling, and tenderness to palpation of the right ankle, the right knee, and bilateral distal femurs. Radiographs of her bilateral legs with attention to her right knee and ankle were obtained and did not reveal any bone abnormality. The orthopedist’s impression was a Salter-Harris I fracture of the right distal tibia and a right patellar tendon strain; she was treated with a long cam walker. The patient returned to the orthopedic clinic 2 weeks later and was no longer having pain. The cam walker was discontinued and the patient was instructed to resume activity as tolerated. In December 2009, the patient’s knee pain returned and she was seen again in the orthopedic clinic. At that visit she was noted to have occasional limping and avoidance of physical activity. She was given a knee brace and crutches in addition to pain medication. Laboratory evaluations revealed an elevated white blood cell (WBC) count of 14.3 1,000/ l (normal range 4.5– 13.5), a hemoglobin level of 11.9 gm/dl (normal range 11.0–14.6), a platelet count of 432 1,000/ l (normal range 150–400), an erythrocyte sedimentation rate (ESR) of 60 mm/hour (normal range 0–22), and a rheumatoid factor (RF) of 30 IU/ml (normal range 0–20). The patient continued to have intermittent pain through mid-December. The pain did not wake her at night, nor did she experience morning stiffness. While she did have some improvement of her pain on naproxen, further diagnostic imaging was pursued. Magnetic resonance imaging (MRI) of her right knee without contrast showed mild distal femoral periostitis without any evidence of effusion, synovial enhancement, or marrow edema. Small lymph nodes were present in the popliteal fossa. The patient continued on her current therapeutic regimen of naproxen. The patient subsequently began to have right shoulder pain after a mechanical fall on the shoulder while using her crutches. Because the patient’s pain persisted into late December, she was prescribed a 5-day course of prednisone (15 mg daily) and referred to a pediatric rheumatologist. The patient was given an appointment to be seen in the clinic the following week and in the interim, a 3-phase bone scan was recommended. The bone scan revealed no abnormality within the knees; however, there was increased uptake on all 3 phases within the right distal tibia/ankle. After these results were reported, the patient was directly admitted to the hospital for further evaluation and management. Upon presentation to the hospital, the patient endorsed having temperatures ranging from 99– 101°F as well as a 3-pound weight loss. The patient had had some blood work done a week prior to admission to the hospital by her primary care physician that showed a normal WBC count of 7.1 1,000/ l, a hemoglobin level of 12.2 gm/dl, a platelet count of 461 1,000/ l, an elevated C-reactive protein (CRP) level of 104.8 mg/liter, and an ESR of 80 mm/hour.