[Richter's syndrome and acute transformation: two terminal haematological complications of chronic lymphoid leukaemia (author's transl)].

Two cases of CLL terminating in Richter's syndrome and in blastic crisis raise the problem of the physiopathological signification of these unusual complications. Richter's syndrome is described as a "histiocytic" lymphoma or a Hodgkin's disease supervening on a CLL. It does not seem that these two pictures have actually to be distinguished since clinical and haematological aspects are not different, and histopathologic studies show always atypical aspects with difficulty of an accurate diagnosis. Cases of blastic crisis of CLL are very uncommon. They correspond to the transformation of a CLL in acute lymphoblastic leukaemia. These two terminal complications of CLL suggest they may be interpreted as two pictures of the transformation of the same initial B cellular clone. This hypothesis, highly probable for the Richter's syndrome, has been actually demonstrated for the acute transformation of CLL.