[Monoclonal gammapathy of undetermined significance and autoimmune disease: description of three cases in Senegal].

Monoclonal gammapathy of undetermined significance (MGUS) has rarely been reported in African literature. The purpose of this article is to describe 3 cases of MGUS observed in women aged 63, 54, and 44 years in Senegal. All three patients had previously documented autoimmune disease, i.e., auto-immune thrombopenia, multiple auto-immune disease (comprising Sjögren's syndrome, polymyositis and vitiligo), and Sjögren's syndrome. Diagnosis of MGUS was made thanks to routine protein electrophoresis that demonstrated a monoclonal peak in the gammaglobulin area in all patients. Serum protein binding showed the IgG lambda subtype in one case and IgG kappa subtype in two cases. Medullogram findings were unremarkable with nondystrophic plasma cell rates ranging from 1 to 4%. Bisphophonate therapy was undertaken along with the recommended treatments for the associated autoimmune diseases, i.e., prednisone, hydroxychloroquine, and methotrexate. Treatment was successful in all three patients with stabilization of the associated diseases and of the monoclonal peak on subsequent electrophoresis. As of this writing, the mean duration of follow-up was 3 years. MGUS that has been uncommon in the African hospital setting should be screened for in all older patients or in patients presenting infection (especially due to virus) or autoimmune disease (as in the three cases presented herein). More systematic use of serum protein electrophoresis should reveal an increased incidence of MGUS. Diagnosis of MGUS requires regular clinical and laboratory surveillance due to the risk for complications of malignant hemopathies, especially multiple myeloma.