The first of the three types is “enhanced-fibrinolytic-type DIC”, as represented by the DIC associated with aortic aneurysms. Underlying diseases causing enhanced-fibrinolytic-type DIC include hemangiomas and vascular malformations (e.g., Kasabach-Merritt syndrome
[27[1][2],
28], Klippel-Trenaunay-Weber syndrome
[29][3], blue rubber bleb nevus syndrome
[30,31,32][4][5][6]), acute promyelocytic leukemia
[13,33[7][8][9][10],
34,35], prostate cancer
[36[11][12],
37], and severe coronavirus disease 2019 (COVID-19) (
Table 1)
[38,39,40,41,42,43,44][13][14][15][16][17][18][19]. In enhanced-fibrinolytic-type DIC, multiple fibrin clots produced by marked coagulation activation dissolve one after another due to the marked activation of fibrinolysis. As a result, ischemic organ damage due to multiple microthrombi is rarely seen as a clinical manifestation
[45][20]. In contrast, severe bleeding symptoms are more likely to occur with the dissolution of hemostatic thrombi. Characteristic laboratory findings include a low platelet count, a normal-to-prolonged prothrombin time (PT), and a shortened-to-prolonged activated partial thromboplastin time (APTT). In other words, diagnosing or excluding DIC based on PT and APTT alone is not possible. Both thrombin-antithrombin complex (TAT) (or prothrombin fragment 1 + 2 [F
1+2]), a marker of coagulation activation, and PIC, a marker of fibrinolysis activation, are significantly increased. Due to the enhanced fibrinolysis, the FDP/D-dimer ratio is increased. In other words, FDP levels increase markedly while D-dimer levels show only a mild to moderate increase (
Table 2). In addition, levels of PAI-1, a fibrinolytic inhibitor, are normal or only mildly elevated
[46][21]. Concentrations of α
2PI are markedly decreased, and especially when it is less than 50%, caution should be taken against major bleeding. Fibrinogen levels are also markedly decreased in typical cases, not only because of the consumption associated with the dissolution of multiple microthrombi, but also because of the degradation of fibrinogen by plasmin.