A 12-year-old Caucasian girl presented to our clinic with a history of worsening the left thigh pain for the last 3 months. She was previously healthy, with no history of trauma, and neither she nor her mother could recall any triggering factor for the onset of the pain. There was a decrease in the appetite but no weight loss or fever. At the time of initial evaluation, she was experiencing pain throughout the day and night. She quantified her pain as 8 out of 10 in the visual analog scale (VAS). She had stopped all physical activities completely and was walking with the aid of crutches. The thigh was slightly swollen and was very tender to light touch, with quadriceps atrophy, but no increase in local temperature. The active and passive ranges of motion of the hip and the knee were globally decreased, due to severe pain. The rest of the clinical examination was normal, in particular, no foci of infection were apparent elsewhere in the body, and no skin conditions were detected. She had no pets, no history of travel, and her familiar history was unremarkable. Her initial blood work revealed only a slight increase in the erythrocyte sedimentation rate (24 mm/h).
The initial radiographs of the left thigh showed a proximal third diaphyseal lesion of the left femur with aggressive appearance (Fig. 1). It was a centro-medullary, permeative lesion with ill-defined margins and a wide zone of transition. There was cortical thickening with areas of scalloping and cortical erosion, and circumferential onion skin appearance denoting moderately aggressive periosteal reaction. No Codman's triangle or sunburst appearance, indicating faster and more aggressive periostitis, were visible. MRI showed a 12-cm medullary lesion with hyposignal in T1-weighted and hypersignal in fat-suppressed T2-weighted images, with medullary enhancement after contrast injection. There were areas of cortical disruption, extensive periosteal reaction and perilesional soft tissue edema, but no soft tissue invasion (Fig. 2 and 3).
Needle biopsy was performed 2 weeks after the initial presentation for microbiological and pathological evaluation, and no evidence was found for infection or tumor (Fig. 4). Serology for Bartonella, Brucella, Salmonella, Tularemia, Coxiella and Mycobacterium tuberculosis were negative. The patient was kept under observation by the tumor team. She was taking acetaminophen for pain relief and the clinical picture remained unaltered for the next month. A second biopsy was obtained through a mini-open approach again, showing no evidence of tumor or infection. At this point, the diagnosis of CRMO was considered, and a scintigram was obtained, which showed unifocal heterogeneous uptake at her left femoral diaphysis, with no other suspicious hot spots. She was then started on 250 mg naproxen t.i.d. with 20 mg omeprazole, 10 mg prednisone daily and a single dose of 30 mg pamidronate. Her VAS score showed initial improvement, from 8 to 3, with pain affecting her only on weight-bearing and no pain at night.
She was maintained on this regimen for 6 months. During this period, she also experienced isolated episodes of pain on her right thigh and on her left ankle, with no abnormal findings on the radiographs. After an 18-month follow-up, she demonstrated progressive improvement of her left thigh pain that occasionally recurred with less and less frequency. Although she was walking without crutches, she was still restricted from physical activity.