[Monoclonal gammopathy of undetermined significance (MGUS): interpretative shades of analysis and sometimes serious clinical consequences].

The etiological assessment of a monoclonal gammopathy is currently standardized, the decisional algorithms allowing a sufficiently precise classification to consider the care, wait or therapeutic. The purpose of this review is to recall the difficulties concerning the interpretation of certain biological investigations and to point out the potential complications of monoclonal gammopathies labeled as "benign". The cooperation between clinicians and biologists is in all cases essential, allowing to propose on a case-by-case basis the best adapted explorations.