Primary progressive multiple sclerosis and generalized myasthenia gravis: an uncommon association.

The co-occurrence of myasthenia gravis (MG) and multiple sclerosis (MS) is rare, and in all the described cases MS had a relapsing-remitting course and the diseases had a benign clinical evolution. We describe herewith a patient with primary progressive MS (PPMS) and generalized MG with severe clinical course. This is the first report on a case of PPMS associated to MG. Studies on the histology and pathogenesis show that neurodegeneration is predominant over inflammation in PPMS, even if cellular and humoral immune-mediated mechanisms are thought to maintain a crucial importance in the development and progression of this form of disease. In the present case, the detection of cerebrospinal fluid IgM oligoclonal bands support the hypothesis of a possible role of antibody-mediated immunity in PPMS and suggest that humoral immunity may take part in the concomitant development of both MS and MG.