Diffuse large B-cell non-Hodgkin lymphomas: the clinical relevance of histological subclassification

In the REAL classification the diffuse large B-cell non-Hodgkin lymphomas ( NHL) are grouped together, because subclassifications are considered to lac k both reproducibility and clinical significance. Others, however. claim th at patients with an immunoblastic NHL have a worse prognosis than patients with other types of diffuse large B-cell NHL. Therefore, we investigated th e prognostic and clinical significance of histological subclassification of diffuse large B-cell NHL in a uniformly treated series of patients. For th is retrospective study, all patients diagnosed as having an immunoblastic ( IB) B-cell NHL by the Lymphoma Review Panel of the Comprehensive Cancer Cen ter Amsterdam (CCCA) between 1984 and 1994, and treated according to the gu idelines of the CCCA, were analysed. Patients with a centroblastic polymorp hic subtype (CB-Poly) or centroblastic (CB) NHL by the Lymphoma Review Pane l who were treated in the Netherlands Cancer Institute during the same peri od according to CCCA guidelines were used as reference groups. All patients ' records were reviewed. Clinical parameters at presentation, kind of thera py and clinical outcome were recorded. All available histological slides we re separately reviewed by two haemato-pathologists. One hundred and seventy -seven patients were included in the study: 36 patients (20.3%) with an IB NHL, 69 patients (39%) with a CB-Poly NHL and 72 patients (40.7%) with a CB NHL. The patients with an IB NHL tended to be older and presented more oft en with stage I or II and one extranodal site than patients with a CB and C B-Poly NHL, None of the subtypes showed a clear preference for localization in a particular site. The patients with IB or CB-Poly NHL showed a signifi cantly worse prognosis than patients with CB NHL, with a 5-year overall sur vival for patients with CB NHL of 56.3% and for patients with IB or CB-Poly NHL 39.1% and 41.6% respectively. The 5-year disease free survival was 53. 2% for the patients with CB, 32% for the patients with CB-Poly and 26.9% fo r the patients with IB NHL. A multivariate analysis showed that histologica l subtyping was of prognostic significance independent of the International Prognostic Index. This finding merits further exploration in prospective s tudies in order to judge the value of subclassification of large B-cell NHL as a guideline in therapy choice.