Predictive factors for blastoid transformation in the common variant of mantle cell lymphoma

Approximately 20% of the mantle cell lymphoma (MCL) patients present with the blastoid variant at diagnosis. Blastoid changes may occur also during the course of the disease, but factors related to blastoid transformation are poorly understood. In the present study, the incidence and predictive factors for blastoid transformation were analysed among 52 patients who primarily had the common variant of MCL and one or more biopsies taken at the time of disease progression. Blastoid transformation occurred in 18 (35%) patients. The minimum estimated risk of transformation was 42% at 5 years of follow-up. At the time of transformation, all except two patients had systemic lymphoma with lymphatic blasts in the blood. The median survival time after blastoid transformation was 3.8 months compared with 26 months in patients without transformation (P<0.001). The respective survival times as calculated from the initial diagnosis of MCL were 31 and 60 months. Leucocytosis, an elevated serum lactate dehyrdogenase (LDH) level, and a high proliferative activity at diagnosis as assessed by the mitotic count and Ki-67 staining were associated with an increased risk of blastoid transformation, and elevated serum LDH and blood leucocytosis with a short time interval to transformation. We conclude that blastoid transformation is not uncommon during the course of MCL, and is associated with a poor outcome. An elevated serum LDH level, a high cell proliferation rate, and leucocytosis are predictive for a high risk of blastoid transformation in MCL.