Cytogenetic differences between bone marrow and spleen in a case of agnogenic myeloid metaplasia developing blast crisis.

Chromosome studies of cells from bone marrow and spleen were performed in a patient with agnogenic myeloid metaplasia (MM) developing blast crisis after a chronic phase lasting for 6.5 years. The proportions of blast cells were roughly the same in bone marrow and spleen. In the bone marrow 43 % of the metaphases were abnormal with a marker chromosome whereas all spleen metaphases were normal. The results indicate that chromosomal changes associated with blast transformation in MM may occur in the bone marrow prior to such changes in the spleen and support the concept that bone marrow and spleen may constitute relatively separate pools of haemopoietic tissue in chronic myeloproliferative diseases.