Patho-anatomical features of so-called Ph1- chronic myeloid leukemia.

Chronic myeloid leukemia without the Philadelphia chromosome (Ph1-CML) is described and distinguished from chronic myeloid leukemia with the Philadelphia chromosome (Ph1+CML) on the basis of clinical and autopsy findings of four cases. Ph1-CML showed clinical, hematological, and patho-anatomical features which could be regarded as typical. Patho-anatomically Ph1-CML differed from Ph1+CML in the variable maturation of the leukemic proliferation in the bone marrow and extramedullary infiltrates. Up to the terminal phase Ph1-CML can be of an extremely mature cell type. However, it can also show myeloblastic transformation after an initially mature cell stage. Ph1-CML infiltrates are found in tissues and organs which Ph1+CML usually does not infiltrate or only to a low degree until a blastic crisis. On the basis of its course and clinical and patho-anatomical features Ph1-CML looks like an atypical chronic myeloid leukemia. However, it is better called an acute myeloid leukemia of the mature cell type.