Phenotypic APC resistance as a marker of hypercoagulability in primitive cerebral lymphoma.

Thrombosis is the most frequent complication and the second cause of death in patients with malignant disease. Primary central nervous system non-Hodgkin's lymphoma represents a rare pathology. Resistance to APC is usually linked to a factor V (FV) gene mutation changing an Arg 506 to a Gln in the APC cleavage site. Aim: In our study, we aimed at investigating the presence of activated protein C resistance (APC-r) and other markers of hypercoagulability in 25 selected patients with a diagnosis of primitive cerebral lymphoma who had suffered from an ischemic episode of TIA and/or stroke. Patients and methods: 25 selected patients with a diagnosis of primitive cerebral lymphoma and 50 healthy subjects acted as control group, were tested. We measured APC-r, natural clotting inhibitors, F1 + 2, aPTIF and PAI-1 according to international guidelines. Gcnomic DNA was extracted from peripheral white blood cells and in order to detect FV Leiden gene polymorphism. Results: Our results showed that 11 out of 25 patients had a poor response to APC (<= 0.70, which represents the cut-off point in our general population) without deficiencies in natural clotting inhibitors. All patients had high plasma levels of F1+2 and PAI-1 compared to those found in healthy subjects (2.65 +/- 0.75 nM/L vs 0.40 +/- 0.35 nM/L; 67.5 +/- 18.5 ng/mL vs 17 +/- 11.5 ng/mL, respectively). In 9 patients resistance to APC was not associated to a FV gene defect demonstrating that such phenomenon may occur also as an acquired condition. However, the patients with resistance to APC showed the highest plasma values in F1 + 2 and PAI-1. Conclusion: In cerebral lymphoma with hypercoagulability the resistance to APC is not caused by the FV Arg 506 -> Gln mutation (82%). APC resistance not caused by this FV gene defect may be an additional risk factor for thrombophilia in this selected population.