Modification of Kiel and working formulation classifications for improved survival prediction in non-Hodgkin's lymphoma.

The total survival of 203 patients with non-Hodgkin's lymphoma (NHL) was analyzed according to the working formulation (WF) and "expanded" Kiel classifications. The original Kiel classification consisting of low grade (LG) and high grade (HG) forms corresponded well to the LG and HG forms of the WF. When an expanded Kiel containing an intermediate grade (IG) composed of the original LG diffuse group was devised, this gave a much better separation of survival of the three grades as compared with the WF where the survival of IG and HG forms were nonsignificantly different. The main reason for this difference was the inclusion of the so-called centroblastic diffuse form in the HG Kiel, but in the IG according to the WF. In a "modified" WF analysis where this histologic entity was placed in the HG subgroup, the three survival curves then gave excellent separation like the expanded Kiel classification. Since the centroblastic diffuse form (and its analogous forms according to other classifications) has a poor prognosis, it is important that it be so recognized and treated accordingly with aggressive therapy. We propose either our expanded Kiel or modified WF classification of the three grade forms as an excellent predictor of survival.