A major new paper has appeared in Blood about splenic marginal zone lymphoma (aka SLVL). A pan-European group which includes my old unit in Bournemouth have studied chromosomal abnormalities in 330 cases. As we had found before, in our own series, there is a very high incidence of abnormalities (72%) and more than half of which had complex karyotypes. The most common abnormalities were gains of #3 or 3q and 12q, deletions of 7q and 6q, and translocations involving 8q/1q/14q.
SLVL is one of the differential diagnoses for CLL, but it is usually CD5 negative. In this study, however, a quarter of cases were CD5+. Those who were CD5+ were significantly more likely to have trisomy 3/3q, del 6q and trisomy 18 than the CD5-ve cases. However, there was no suggestion that the CD5+ cases were more clinically aggressive. In particular TP53 deletion was not associated with CD5 positivity.
AS has been reported previously some cases of SLVL are mutated and some unmutated. In this series 41% were unmutated and there was an association of these cases with del 7q, but this did not have any impact on overall survival. There was a biased use of IGHV genes. In particular, IGHV1-2 was associated with del7q.
On multivariate analysis the only factors associated with poorer prognosis were age over 65 and hemoglobin less than 12 g/dl - non disease-related factors consistent with the fact that most people die with SLVL, not because of it.