[Extramedullary blast crisis in chronic myeloid leukemia]

Out of 113 cases of blastic crisis (BC) of Ph'-positive chronic myeloid leukaemia (CML), 13 had extramedullary involvement, this being the first BC manifestation in 5 instances. The median interval between extramedullary BC and bone marrow BC in these last was 2 months. Lymph nodes were the commonest extramedullary site of BC (8 cases), followed by osteoperiosteal and central nervous system (CNS). Lymph node BC occurred as generalised lymphadenopathy in most cases. Osteoperiosteal BC was seen as severe bone pain on osteolytic areas, whereas CNS blast crisis occurred as meningeal leukaemia in one case and chloroma in another. Lymphoid phenotype of blast cells was found in only 2 instances. The median survival of the patients after the onset of extramedullary involvement was 3 months.