Children with acute lymphoblastic leukemia (ALL), the most common childhood malignancy, usually present at diagnosis with signs of bone marrow failure. Pallor, fatigue, anemia, fever, neutropenia, and thrombocytopenia are frequent signs. Skeletal manifestations on imaging studies are found in 20-36% of cases [1,2]. These include metaphyseal bands, periosteal new bone formations, lytic lesions, osteosclerosis, osteopenia, and mixed osteolysis and sclerosis [1][2][3]. Generalized osteopenia and vertebral complications have, however, reported in ALL [4]. Our experience with such a child is of interest.She was an 8-year-old female, who was admitted to our Center because of anemia, leukopenia, and thrombocytopenia. Three months earlier, she had experienced a sharp back pain and for this reason was admitted to a local hospital. Radiography and computed tomography of her spine showed collapse of L2, and diffuse severe osteoporosis. Laboratory data were normal, except for the blood sedimentation rate (62 mm/hr). A working diagnosis of juvenile rheumatoid arthritis was entertained, and a plaster cast was applied for a month. When it was removed, the child continued to suffer from diffuse pain and had difficulty in walking. For this reason, physiotherapy was administered for 2 months but her general condition worsened; diffuse bone pain forced her to stay in bed. Because of an altered blood cell count (hemoglobin 8.5 g%; white blood cell 3,000/mm 3 ; platelets 130,000/mm 3 ), the child was transferred to our Center. She was pale, had a very restricted range of motion in her lumbar spine and pain on motion forced her to remain supine. Diffusely enlarged lymph nodes, and both hepato-and splenomegaly were present. Leukemia was suspected and a FAB L1 ALL was confirmed by bone marrow examination. Serum levels of parathormone, calcium, phosphorus, and magnesium were normal, while the calcitonin was 54.4 ng/ml (normal range: 3.1-13.7 ng/ml). The 24-hr calciuria and phosphaturia values were 92 mg/24 hr (normal range: 100-300 mg/24 hr) and 234.6 mg/24 hr (normal range: 400-1,300 mg/24 hr), respectively. Renal and liver function findings were normal. Total-body X-ray films showed lumbar kyphosis and marked rarefaction of trabeculae and spongiosa of the vertebral bodies. The bodies of T4, T7, T9, T10, and L1-4 were collapsed indicating previous fractures (see Fig. 1). A corset was applied and physiotherapy was ruled out. Chemotherapy was started; during the induction phase, prednisone was preferred to dexamethasone, which is known to be more toxic to bone metabolism. Supplementation with oral calcium and vitamin D was ruled out. A prompt clinical and laboratory response followed. DISCUSSIONOsteoporosis in children at the onset of ALL probably has a multifactorial basis. Direct ALL involvement or an indirect effect through osteoclast activating factor, produced by lymphoblasts have been proposed [5]. Low concentrations of activated vitamin D3 and osteocalsin have been considered as possible causes of these alterations in bone metaboli...