P071 Osteoid osteoma in children: About 15 cases

Abstract

Abstract Background Osteoid osteoma (OO)also called osteoblastoma, if the localization is in the spine, is a benign osteoblastic tumor of variable clinical expression, depending on the location of the lesion. It represents 2% to 3% of bone tumours and 15% of benign bone tumours in children. It affects mainly older children and adolescents and most often occurs in the lower limb, especially the femur. The diagnosis is radio-clinical. The aim of this study is to demonstrate the effectiveness of surgical removal of the tumor, the therapeutic difficulty in certain osteoarticular localizations and finally the radio-clinical evolution after surgery. Material & methods We report the radio-clinical outcomes of a series of 15 children (4 girls/11 boys; aged of 03–14 years) with OO operated in our department, over a period of 08 years (2011–2019). Results The OO is located in most of cases of the lower limbs: acetabulum (1 case); femoral neck (3 cases); femoral diaphysis (2 cases); tibial diaphysis (4 cases); distal metaphysis of the tibia (1 case); talus (1 case) and in the spine (3 cases: vertebral body of T3, the posterior arch of T12 and the sacrum S3). Nocturnal pain yielding to aspirin, was the main symptom. It was associated with lameness when walking in patients with location of OO in the lower limbs. Diagnosis was delayed in patients with localization of OO in the spine (after 3 years) and in the talus (after 2 years). Imaging (standard Rx, CT scan and MRI) allowed the diagnosis of OO in all cases (nidus and cocarde image) and assessed the loco-regional impact (compression of the spinal canal in the sacral location; eccentricity of the femoral epiphysis, in the acetabular location, scoliosis in the spinal location). Thirteen children received surgical treatment under fluoroscopic guidance, which consisted of: A surgical abstention was decided in 2 cases: an inaccessible location at the bottom of the acetabulum and the T3 thoracic vertebral body localization in a 6-year-old girl. 12 operated children have good outcomes. However, 03 children experienced post-therapy problems: lumbar pain radiating towards the left thigh in the girl with sacral location (S3) despite the large laminectomy; a relapse 7 months later in the child with the femoral neck localization; A valgus misalignment of the right knee after removal of the OO of the proximal metaphysis of the tibia with a relapse 3 months later. Conclusion OO is a rare, benign tumor. However, certain locations can lead to diagnostic difficulties, loco-regional, organic and functional repercussions and certain constraints on their therapeutic management. Modern imaging helps to improve the care of these patients, both in terms of early diagnosis (scintigraphy, CT scan and MRI) and therapeutic precision (photo-coagulation, radiofrequency ablation).