[Overlap syndromes in rheumatology].

Overlap syndromes in rheumatology present a challenging problem reflecting clinical and immunogenetic heterogeneity of rheumatic disorders. Current statistics refers 25% of the connective tissue diseases to "overlap syndromes". There are three main groups of them, viz. (1) overlap forms of systemic connective tissue diseases, (2) mixed connective tissue disease (Sharp's syndrome), (3) undifferentiated rheumatic disease. Characteristics of these groups are presented based on the published studies and the original data on 100 patients with the most frequent forms of systemic connective tissue pathologies, such as systemic sclerodermias with polymyositis/dermatomyositis (68 patients) and rheumatoid arthritis (32 patients).