[A series of 618 cases of monoclonal gammopathies of undetermined significance: predictive factors of disappearance of monoclonal component or evolution to malignant gammopathies].

INTRODUCTION: How to identify monoclonal gammopathies of undeterminated significance (MGUS) at risk for progression has been studied for the last years.

AIMS: To study the incidence of MGUS in a region with 300,000 inhabitants and factors which associate with a) monoclonal gammopathy disappearance (transient MGUS) b) evolution to malignant gammopathy.

METHODS: Study of 618 MGUS.

RESULTS: Incidence: 30/40 new cases a year with increase to 70 cases a years in the latest years of study. Age and gender: 71,4 y (32-100), male/female ratio 1.4. Associated pathology: infection 328, heart diseases 249, rheumatic diseases 211, liver diseases 108, cancer 80, neuropathy 43. Monoclonal proteins: IgG 407, IgM 78, IgD 2, biclonal 16, triclonal 1; no heavy chain 21, light chain Kappa 389. Variables (mean): monoclonal component: 14 g/l, ESR 32,5, bone marrow: 5,9% plasma cells beta2-microglobulin: 2,59 mg/l, albumin: 3,1g/l, bone survey: normal 39,5%. Evolution: transient MGUS 20 cases. Time to disappearance 2,6 months (1,4-4,6). Evolution to malignant gammopathy 24 cases, time to progression 3 years (IC 1,82-4,3).

RESULTS: Several factors were associatedç with malignant transformation: heavy chain IgA (p < 0,002), ESR (p < 0,001), age < 70 (p < 0,05), bone marrow percentage of plasma cells (p < 0,002) y ostheoporosis (p < 0,005). A MGUS follow up model is suggested.