Extramedullary blast crisis in a patient with chronic myelogenous leukemia in complete cytogenetic and molecular remission on interferon-α therapy

We report the previously undescribed occurrence of extramedullary blast crisis in a patient with chronic myelogenous leukemia in complete cytogenetic and molecular remission on interferon-cc. Development of bilateral testicular swelling prompted a biopsy showing stromal infiltration with CD20 and TdT positive immature cells. On repeated examinations, the bone marrow remained BCR/ABL negative by RT-PCR analysis. However, the cerebrospinal fluid (CSF) contained atypical lymphocytes positive for the P210 BCR-ABL product. Following treatment with testicular irradiation, intrathecal methotrexate, systemic chemotherapy and an unrelated donor transplant, the patient showed no evidence of disease until 9 months post-transplant, when he relapsed in lymphoid blast crisis in both bone marrow and CSF. (C) 2000 Published by Elsevier Science Ltd.