[Mitral valve prolapse and pectus excavatum. Expressions of connective tissue dystrophy?].

Pectus excavatum is a common malformation in diseases of elastic tissue (Marfan, Ehlers-Danlos...). When observed apparently alone it may represent a minor form of dystrophy, implying the same risk of a cardiac lesion. Abnormalities of the thoracic skeleton and echocardiographic mitral valve prolapse is a well established association, suggesting a common disorder of connective tissue. However, there is no absolute proof that this is a statistically significant association. Histological connective tissue changes relating these two markers have yet to be found. Clinical and echocardiographic examinations and skin biopsies were performed in 17 patients with pectus excavatum. Mitral valve prolapse was detected in 65% of cases (associated in 1 out of 3 cases with tricuspid valve prolapse). In 53% of cases electron microscopy showed abnormal skin collagen and elastin. Collagen abnormalities were twice as common as those of elastin and could be associated. Mixed changes of thinning of elastin and collagen fibres of irregular calibre were particularly suggestive. Pectus excavatum would therefore seem to be the expression of a minor form of dystrophy of collagen and elastin tissues and a clinical marker of possible mitral valve prolapse.