A Challenging Case of IgD Kappa Multiple Myeloma Associated With Primary Amyloidosis: Importance of Serum Free Light Chains in Monitoring Treatment Response and Disease Relapse

Abstract

Multiple Myeloma (MM) is a malignancy of B cells characterized by an atypical proliferation of plasma cells. IgD MM has a very low incidence (2% of total MM cases) and it´s characterized by an aggressive course and a worse prognosis than other subtypes. The serum free light chains (sFLC) are very important markers for monitoring patients with MM and other monoclonal gammopathies. When the sFLC are present in low concentrations, it is often difficult to detect them by conventional methods such as serum protein electrophoresis and serum immunofixation. This case is a good example of the utility of sFLC in the monitoring of treatment and relapse of patients with MM. The sFLC determinations detected when chemotherapy applied was not being completely effective and it predicted a relapse before new clinical findings were present. We report the rare case of a patient diagnosed of IgD MM with associated light chain kappa Primary (AL) Amyloidosis and characterized by clinical findings of very bad prognosis (high levels of sFLC kappa at diagnosis, high renal impairment and subsequent development of intracranial plasmacytoma), aggressive course and refractory to several lines of treatment.