MGCS: where do we stand today?

Monoclonal gammopathies of clinical significance (MGCS) are a heterogeneous group of disorders characterized by the presence of an indolent B-cell or plasma-cell clone producing a toxic monoclonal immunoglobulin resulting in end-organ dysfunction. MGCS is a clinicopathologic diagnosis that requires the demonstration of a monoclonal immunoglobulin in the correct clinical setting. The most common MGCS syndromes are renal, neurologic, and cutaneous, although hematologic and multi-organ MGCS syndromes are also increasingly recognized. Therapy most commonly targets the underlying clonal population; immunoglobulin-targeting therapies as well as complement and cytokine antagonists have emerged for selected MGCS syndromes and may be temporizing in a subset of patients. Other chapters review renal and neurologic MGCS; this chapter focuses on hematologic and multi-organ MGCS syndromes.