Bone tumor as the first clinical sign of acute leukemia is a rare event. We report a new case, a 14 years old girl who was admitted for a left radial tumour without adenopathy, hepatosplenomegaly or extra nodal involvement. Biological parameters were as follows: hematocrit 23%, white cell count 20,300/mm3 with normal differential distribution, platelet count 248,000/mm3. No blast cells were noted. Bone marrow cytological examination revealed 15% of vacuolated, slightly basophilic, PAS positive blasts. The immunophenotype performed by FACS analysis was positive for CD9, CD10, CD19, CD22, intra cytoplasmic Cμ and negative for CD34, CD20 and surface immunoglobulins. The histopathological examination of the tunor identified a lymphoid proliferation bearing the same immunophenotype: the EBV RNA in situ hybridization was negative. Though cytogenetic studies were inconclusive, a E2A PBX1 fusion transcript encoded by the (1;19) (q23;p13) translocation was detected by RT PCR and hybridization. The present case is of particular interest since the clinical pattern at diagnosis of such leukemia type has not yet been documented. Though the L3 like blasts morphology was reminiscent of a Burkitt lymphoma, the cytochemical reaction was well as the immunophenotype and the molecular biology confirmed the diagnosis of pre B ALL. This case illustrates the interest of using conjunction of cytology, immunology, molecular biology for the diagnosis of a t(1;19) (q23;p13) atypical pre B ALL.
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Favier, R., Firat, H., Adam, M. et al. A t(1;19) (q23;p13) ACUTE LYMPHOBLASTIC LEUKEMIA (ALL) REVELED BY A RADIAL BONE TUMOR 98. Pediatr Res 41, 763 (1997). https://doi.org/10.1203/00006450-199705000-00117