[Monoclonal gammopathy related disorders].

Monoclonal gammopathy related disorders. The presence of a monoclonal immunoglobulin in serum or urine reflects the existence of an abnormal clone of B cells. In case of large tumor mass, patient need treatment. Sometimes, the clone is nearly undetectable, but gammopathy is associated with complications not directly related to tumor cells but to the presence of the monoclonal immunoglobulin. Most often, lesions result from the deposit of monoclonal immunoglobulin, organized or not. Other mechanisms include autoantibody activity, immune complex formation or deregulation of the complement system. Finally, in some cases, the physiopathology remains to be determined. The downstream complications of gammopathies are protean and can affect various organs, mainly the kidney, the skin and the peripheral nervous system. A delayed diagnosis may be life-threatening or functional. A rigorous clinical examination, and appropriate explorations are therefore necessary in order to put in place a suitable therapy, targeting most often the underlying clone.