Resolution of Factor X Deficiency in Primary Amyloidosis Following Splenectomy

A 57-year-old man with primary amyloidosis was initially seen with hematuria, cutaneous bleeding, and hepatosplenomegaly. Factor X was determined to be 10% to 16% of normal plasma values. Administration of vitamin K-dependent factor concentrate transiently improved in vitro clotting tests but did not alter the clinical course. Following a splenectomy, bleeding ceased and factor X levels returned to normal, remaining so despite discontinuation of factor concentrate infusion. Amyloid fibrils extracted from the patient's spleen were determined to be derived from λV1 light chains. The importance of splenectomy as an effective therapeutic modality is discussed.