[Clinical features of five cases of acquired factor V deficiency].

Acquired factor V deficiency is a rare disease that presents with various bleeding symptoms because of the acquired production of factor V inhibitors and decrease in factor V activity. We have experienced five cases of acquired factor V deficiency diagnosed on the basis of abnormalities in coagulation tests in the last 10 years. All five patients were older men, of whom one had no bleeding symptoms, and three had a history of renal failure and malignant tumors. In the cross-mixing test, two of three cases demonstrated an inhibitor pattern, but one case showed a deficient pattern. In all cases, steroid treatment improved factor V activity as well as prothrombin time and activated partial thromboplastin time. However, patients with intracranial hemorrhage had a poor prognosis. Although this disease is rare, careful management is necessary, especially in the absence of bleeding symptoms and where cross-mixing test does not show an inhibitor pattern.