Differential diagnosis and therapeutic limitations in a rare case of acquired factor X deficiency

Abstract

Acquired Factor X deficiency is a rare coagulation disorder, which predominantly presents with mucocutaneous bleeding, and is associated with systemic amyloid light-chain (AL) amyloidosis in the vast majority of cases. There are, however, rare case reports of its occurrence in the context of acute respiratory infection, various malignancies, and following exposure to certain medications. We report a case of an 82-year-old man who presented with a Non-ST segment elevation myocardial infarction, decompensated biventricular failure, Respiratory Syncytial Virus (RSV) pneumonia, active haemoptysis, and a profound coagulopathy. Initial laboratory studies were consistent with acquired isolated Factor X deficiency (prolonged Prothrombin Time and Activated Partial Thromboplastin Time, correction with mixing studies, factor X level < 3%), however Congo red staining for AL amyloidosis on abdominal fat biopsy was negative. The patient was acutely managed with prothrombinex therapy with partial but temporary reversal of their coagulopathy and resolution of their bleeding. Unfortunately, solid organ biopsy was deemed unsafe and the patient passed away from recurrent sepsis before a formal diagnosis of the underlying aetiology could be made. This article describes a diagnostic approach to coagulation factor deficiencies and AL amyloidosis, and their limitations in the coagulopathic patient. It further reviews the correlation between severity of bleeding complications and Factor X coagulant activity. Lastly, it outlines potential treatment options for acquired Factor X deficiency; such as coagulation factor replacement, plasma exchange, and targeted amyloidosis therapies.