A Rare Cause of Acquired Factor X Deficiency in an 87-Year-Old Female

Factor X deficiency is a rare coagulopathy that can be inherited or acquired. Acquired factor X deficiency has been associated with plasma cell dyscrasias, amyloids, and use of vitamin K antagonists. Of plasma cell dyscrasias, most cases in the literature have been associated with multiple myeloma with or without concomitant AL amyloidosis. Here, we present a rare case of acquired isolated factor X deficiency in an elderly patient with immunoglobulin A (Ig A) monoclonal gammopathy of undetermined significance (MGUS). Herein, we highlight a rare cause of acquired factor X deficiency, and we hope to contribute to the growing literature of plasma cell dyscrasias associated with factor X deficiency.

Response of factor X deficiency to darutumumab in the treatment of AL amyloidosis: a novel finding

We report a case of progressive light-chain amyloidosis (otherwise known as AL amyloidosis) with acquired factor X (aFX) deficiency with a complete haematological response and rapid normalisation of FX levels following daratumumab monotherapy. To our knowledge, this is the first case report documenting successful treatment with daratumumab of aFX deficiency secondary to AL amyloidosis. The patient responded well to this therapy, with excellent symptomatic and quality of life improvements as well as a reduction in bleeding manifestations. This case highlights the value in considering daratumumab treatment when AL amyloidosis is complicated by FX deficiency.