[Osteoid osteoma of the inferior articular process of L5 associated with a bilateral spondylosis: a case report].

We report the case of an 8-year-old boy who presented an osteoid osteoma of L5 associated with bilateral spondylolysis involving the same vertebra. Diagnostic bone scintigraphy is highly contributive in children presenting back pain. For us, it is the first intention exploration in patients with isthmic lysis seen on the plain x-ray. Symptomatic spondylolysis is the most frequent cause of back pain in children and is much more frequent than vertebral osteoid osteoma. The presence of isthmic lysis associated with focal uptake on the bone scintigraphy is highly suggestive of symptomatic spondylolysis. In this context, magnetic resonance imaging should be performed for both diagnostic purposes and prognostic assessment. The degree of bone and soft tissue edema in the present case was unusual for symptomatic spondylolysis. Complementary computed tomography finally established the diagnosis of osteoid osteoma of the posterior vertebral arch. To our knowledge, the association of osteoid osteoma with bilateral spondylolysis on the same vertebra has not been described elsewhere. In children, the diagnosis of symptomatic spondylolysis can only be established after ruling out other causes of back pain. The diagnosis of osteoid osteoma must be kept in mind.