Co-occurrence of monoclonal gammopathy and myelodysplasia: a retrospective study of fourteen cases.

We report a series of 14 patients with myelodysplastic syndrome (MDS) accompanied by a monoclonal gammopathy unrelated to therapy. Twelve of these had monoclonal gammopathy of undermined significance (MGUS) and two had smoldering multiple myeloma. These cases represent 10.2 % of all MDS cases seen at our institution over a 14-year period (January 2000 to December 2013). The incidence of MGUS was determined to be significantly higher in MDS than in age-matched concurrent controls by χ(2) test. Absence of prior chemotherapy and simultaneous presentation of MDS and MGUS in most cases suggest true co-occurrence of the two disorders. MGUS was found in all WHO subtypes of MDS with a wide range of risk factors. However, 11 out of the 12 MDS cases accompanied with MGUS had relatively low karyotypic risks. In addition, serum M protein levels remained largely unchanged in 4 cases of MGUS for which serial determinations were performed. These findings indicate that MGUS may not affect the prognosis of MDS.