Refractory T cell acute lymphoblastic leukemia with unusual karyotype and interesting immunophenotype.

Karyotype, immunophenotype, and molecular studies are important in the evaluation of Acute Lymphocytic Leukemia as these data provide diagnostic as well as prognostic information. We present a case of acute lymphoblastic leukemia with unusual cytogenetics, 45,XY,i(7q),der(9)t(3;9)(q12;p22),del(12)(p12), :der(18)t(3;18)(p14;q22),-3. This karyotype is hypodiploid, showing loss of chromosome 3, a very rare occurrence. Hypodiploidy and translocations are suggestive of a poor clinical outcome. Cytogenetics also showed a chromosome 12p deletion which has been implicated in the oncogenesis of some acute leukemias. Immunophenotype by flow cytometry was positive for CD7 and CD10, T, and precursor B cell markers respectively. Given the specificity of CD7 for T cell processes, it was felt that the flow cytometry was more suggestive of a T cell process. Gene rearrangement studies showing a T cell receptor rearrangement helped confirm the T cell lineage of this malignancy. Hypodiploidy and T cell phenotype are indicators of poor prognosis. Interestingly this patient was refractory to two conventional chemotherapeutic protocols and finally responded to an unconventional protocol of high dose Ara C, etopside, and L asparaginase.