Monoclonal gammopathy

This code signifies the presence of a monoclonal immunoglobulin (M-protein) in the blood or urine, without meeting the diagnostic criteria for multiple myeloma, Waldenström's macroglobulinemia, or other B-cell lymphoproliferative disorders. It represents a pre-malignant or indeterminate condition where a single clone of plasma cells produces an abnormal protein.

Apply this code when documentation confirms monoclonal gammopathy of undetermined significance (MGUS) or other unspecified monoclonal gammopathy. This typically follows laboratory findings of an M-spike on serum protein electrophoresis (SPEP) or immunofixation (IFE), in the absence of end-organ damage attributable to a plasma cell dyscrasia.

• Do not use this code if the patient has a definitive diagnosis of multiple myeloma (C90.00-C90.02) or Waldenström's macroglobulinemia (C88.0).
• Ensure documentation specifies "undetermined significance" or similar phrasing to differentiate from active malignant conditions.
• This code is often a primary diagnosis when the patient is being monitored for progression to a more serious plasma cell disorder.