[Life-threatening hypercalcemia as the initial presentation of childhood acute lymphoblastic leukemia].

Hypercalcemia in childhood acute lymphoblastic leukaemia (ALL) is a well-known but uncommon complication. Here, we report a case of B-ALL in which the first signs were life-threatening hypercalcemia associated with diffuse osteolytic lesions with no hematologic abnormalities. We draw attention to the difficulties formally establishing the ALL diagnosis. Bone marrow examinations must be repeated if necessary. Furthermore, biological, cytogenetic, and molecular aspects need to be investigated. Measurement of intact PTH can exclude hyperparathyroidism. PTHrP is possibly involved in hypercalcemia processes induced by tumor cells. The t(17;19) translocation and its E2A-HLF transcript fusion, which have been thought to be a poor prognostic factor, must be determined. Regarding severe hypercalcemia control, treatment is based on both underlying disease management and serum calcium level reduction with aggressive hydration and if necessary bisphosphonates.