Subclassification of diffuse large B-cell lymphomas according to the REAL classification: Distinction of immunoblastic and non-immunoblastic subtypes / 대한내과학회지

ABSTRACT

BACKGROUND: Diffuse large B-cell lymphoma (DLBL) category in the REAL classification includes histologically heterogeneous subtypes in Working Formulation or Kiel classification. Some investigators insist that the prognosis of B-cell immunoblastic lymphoma (IBL) is worse than other types of DLBL. This study was performed to determine the clinical significance of histological subclassification of DLBL. METHODS: All non-Hodgkin's lymphomas diagnosed at 3 hospitals in Korea between 1989 and 1995 were reclassified according to the REAL classification. Medical records of 404 patients with DLBL were reviewed. Their pathologies were categorized into IBL or non-IBL according to Working Formulation. We compared clinical characteristics and treatment outcomes of IBL with those of non-IBL. RESULTS: Of 404 DLBL patients, 341 cases (84%) were classified as non-IBL and 63 cases (16%) as IBL. Male patients were more common in IBL than in non-IBL (76% vs. 62%). IBL presented more often with advanced stage (III or IV) and B-symptoms than non-IBL (57% vs. 42%, 40% vs. 27%, respectively). In other clinical characteristics, no significant differences were found between the two groups. Complete response rates were 59% in IBL and 68% in non-IBL (p=0.137). With a median follow-up of 52 months (range 1-108 months), the median progression-free survival was 11 (95% confidence interval [95% CI] 8-14) months for IBL and 41 (95% CI 18-64) months for non-IBL (p=0.004). The median overall survival was 21 (95% CI 13-29) months for IBL and 72 months for non-IBL (p=0.002). A multivariate analysis for progression-free survival and overall survival showed that histological subtype (non-IBL vs. IBL) was a significant prognostic factor independent of International Prognostic Index (p=0.013 for progression-free survival, p=0.003 for overall survival). CONCLSUION DLBL includes heterogeneous subtypes with different prognosis. Subclassification of DLBL into IBL and non-IBL has prognostic significance. IBL needs to be separated from other types of DLBL.