Acquired, non‐amyloid related factor X deficiency: review of the literature

Summary.  Factor X (FX) deficiency is a rare coagulopathy due to congenital deficiency (Stuart–Prower disease) or in association with primary amyloidosis. Acquired and isolated FX deficiency occurring in the absence of a plasma cell dyscrasia has only been infrequently described. After recently diagnosing and treating a case of acquired, isolated FX deficiency, we embarked upon a review of the literature to help guide clinicians who may face this clinical situation. The literature was reviewed to identify cases of isolated, acquired FX deficiency unrelated to congenital deficiency, use of vitamin K antagonists, or amyloidosis. There were 34 cases of acquired FX deficiency identified, occurring in association with malignancy, drug exposure and infection. The majority of described cases (38%) were preceded by a non‐specific respiratory viral illness. The initial presentation was variable, ranging from no bleeding to life‐threatening haemorrhage. Twenty per cent of patients had musculoskeletal bleeding resembling patients with haemophilia. Both the prothrombin time and the activated partial thromboplastin time were markedly prolonged in nearly all patients. In 26% of patients, a specific FX inhibitor was identified. Numerous therapies have been utilized in patients with acquired FX deficiency including high‐dose glucocorticoids, plasma exchange with fresh frozen plasma and intravenous immunoglobulin. In 18% of patients, the coagulopathy resolved spontaneously. All patients achieved a complete recovery. Acquired factor X deficiency is a rare disorder, commonly associated with a preceding viral illness and a circulating FX inhibitor. Although multiple treatment modalities have been described with variable success, in many cases, it is a self‐limited condition.