[Pediatric acute lymphoblastic leukemia presenting with bone and joint pain].

We report on three cases of pediatric acute lymphoblastic leukemia presenting with bone pain and arthralgia as initial symptoms. At the first visit, their primary signs were recurrent bone pain and arthralgia, without significant peripheral blood abnormalities. It took 2-4 months to confirm the diagnosis from the onset of arthralgia due to this atypical presentation of the disease. Definitive diagnosis was obtained by bone marrow examination, and in all cases, complete remission was achieved by chemotherapy. As a feature of imaging, MRI exhibited diffuse bone marrow signal changes in T1-weighted images, and FDG-PET showed extensive abnormal bone marrow uptakes. In cases 2 and 3, it was difficult to diagnose by bone marrow aspiration from the iliac bone, but definitive diagnosis was obtained by bone marrow aspiration from the tibia, in which FDG-PET showed increased uptake. FDG-PET was therefore considered useful for the selection of bone marrow aspiration sites. In cases presenting with recurrent migratory bone pain and arthralgia, we need to consider performing bone marrow aspiration and imaging, such as MRI and FDG-PET, for early diagnosis and treatment of leukemia.