Pemphigus and myasthenia gravis

Various forms of true pemphigus have been reported to occur with myasthenia gravis, with and without thymoma, more frequently than can be ascribed to chance. A57-year-old woman with myasthenia gravis in remission developed pemphigus foliaceus. No roentgenologic evidence of a thymoma was present. Antinuclear antibodies caused interference with indirect immunofluorescent determination of pemphigus antibody. Indirect immunofluorescent studies showed no evidence for cross-reactivity between intercellular substance antibody and thymic components, as is found in the case of antiskeletal muscle antibodies with thymic myoid cells. The concurrence of these two diseases may involve the failure of a subgroup of thymic-dependent lymphocytes to suppress underlying autoimmune phenomena.