Background: Tissue factor (TF), the principal initiator of the extrinsic coagulation pathway, is expressed by many tumors and can be released into the bloodstream on plasma microparticles (MPs). Experimental studies indicate that TF may facilitate hematogenous metastasis by promoting tumor cell-induced microvascular thrombosis, but clinical data supporting this hypothesis is sparse. Case Reports: Here, we report 2 unusual cases of rapidly progressive solid malignancies (gastric and urothelial carcinoma). In both patients, cancer cell dissemination with diffuse bone marrow involvement was either strongly suggested by leukoerythroblastic changes on peripheral blood smear or directly proven by positive findings on aspiration cytology. Furthermore, laboratory evidence of thrombotic microangiopathy (TMA) and disseminated intravascular coagulation was accompanied by new-onset severe pulmonary hypertension and a hemolytic uremic syndrome-like disorder in the gastric and the urothelial carcinoma patient, respectively. TF-specific procoagulant activity of isolated plasma MPs, as assessed by single-stage clotting assay, was dramatically increased in both patients compared to healthy controls (21- and 55-fold), and primary tumor samples stained strongly positive for TF by immunohistochemistry. Conclusion: TMA was likely caused by TF-triggered tumor cell embolization in both patients. Further clinical evidence is thus provided that TF directly links coagulation activation to cancer cell dissemination.