stage 4 diffuse b cell lymphomastage iv large b cell lymphomastage 4 large cell lymphomastage 4 diffuse large cell lymphomastage 4 b cell lymphoma prognosisb cell lymphoma diagnosisaggressive large b cell lymphomapictures of b cell lymphomalarge b cell lymphoma prognosisb cell malignant lymphomadiffuse large b cell lymphomab cell lymphocytic lymphoma