Chronic myeloid leukemia as a secondary malignancy after ALK-positive anaplastic large cell lymphoma

SummaryThe development of Philadelphia chromosome–positive chronic myelogenous leukemia (CML) in the adolescent population is very rare. CML occurring as a secondary malignancy in individuals treated for anaplastic large cell lymphoma (ALCL) is also rare. We present the case of a 16-year-old adolescent boy who developed a right orbital mass that was diagnosed as ALCL with the t(2;5)(p23;q25) chromosomal aberration. Four years after receiving treatment for ALCL, he presented with a swollen leg and a white cell count of 431 000. Peripheral blood and bone marrow evaluation revealed a myeloproliferative disorder. Cytogenetic and molecular studies demonstrated the presence of t(9;22). We present the histopathologic, molecular, and cytogenetic findings of this patient's initial presentation with systemic ALCL as well as his secondary presentation with CML 4 years later. Therapy-related CML and non–therapy-related secondary CML are discussed as potential explanations of this highly unusual clinical presentation.