Changes over the course of time in histological subclassification of Hodgkin's disease in Denmark

Primary diagnostic lymph node biopsies from 317 patients with Hodgkin's disease pathologic stage (PS) I or II in the prospective randomised trial of the Danish National Hodgkin Study and from 174 patients with Hodgkin's disease stage III or IV examined and treated at the Finsen Institute, Copenhagen, Denmark, were reviewed. The original diagnosis of Hodgkin's disease was made during the period 1971-1983 and was a result of a consensus among three members of a panel of pathologists. In the current study, the histological material was re-examined in order to critically consider and exclude cases which are not histologically diagnostic but microscopically bear resemblance to Hodgkin's disease, to obtain a uniform subclassification in accordance with recent new points of the Rye classification, to examine possible changes in incidence over the course of time and to examine the NS subclassification according to the BNLI proposals. Two cases (0.4%) were reclassified as not being Hodgkin's disease, and 489 cases (99.6%) were reclassified as Hodgkin's disease in the subgroups: LP 7.5% (16.7%), NS 65.1% (54.7%), MC 21.9% (26.4%) and LD 1.2% (1.2%) (the numerals in brackets state the original subgroups). In 9.7% of the cases, the subclass could not be assessed, because the biopsies were too small for subclassification. The difference between the original and the present subclassification could be explained partly by a change in the criteria for the different subgroups and partly by interobserver disagreement. In the histologically reclassified material, the Rye classification lost its prognostic significance. It was not possible to demonstrate a gradual change over the course of time in the relative number of cases in each subgroup.(ABSTRACT TRUNCATED AT 250 WORDS)