Pectus Excavatum

► [Inward depression of the lower portion of the sternum]

Pectus excavatum, or funnel chest, is usually an isolated anomaly. However, it can also occur in association with other skeletal and nonskeletal defects or in the context of heritable disorders of the connective tissue, including Marfan syndrome and Ehlers-Dan-los syndrome. Moreover, the occurrence of idiopath-ic scoliosis in patients with anterior chest wall deformity is higher by a factor of 10 than in the general population (Waters et al. 1989). Pectus excavatum is usually present at birth and is progressive during growth. Its prevalence is 8 per 1000 births, with a male-to-female ratio of about 2:1. The degree of sternal depression varies from a shallow cup to a deep funnel (Fig. 2.7). Regardless of the degree of lower sternum depression, the manubrium remains at the normal level. Pectus excavatum has been classified into a broad and a localized type, according to the clinical extent of the sternal depression. In pectus excavatum broad type (Fig. 2.8) the costal cartilages are involved to a greater extent, with inward bending beginning at the level of the costochondral junctions. Impaired growth of the posterior portions of the cos-tochondral junctions coupled with relative overgrowth of the anterior unaffected portions, is probably responsible for the inward bending of the sternum and thus for the development of the broad type

Pectus Excavatum
Fig. 2.8. Pectus excavatum, broad type. Note the significant sternal depression beginning at the level of the costochondral junctions. (From Haje et al. 1999)
Female Pectus Excavatum
Fig. 2.9. Pectus excavatum, localized type. The sternal depression is more focal than in the broad type. The costochondral junctions are minimally involved. The limits of the sternum and most inferior costal arches are marked with dashed lines. (From Haje et al. 1999)

of pectus excavatum (Haje et al. 1999). In pectus excavatum, localized type (Fig. 2.9) impaired growth at the posterior costal growth plate and anterior portions of the sternum are likely to combine to determine the sternal deformity (Haje et al. 1999). Anterior prominence of the lowest ribs can accompany both varieties of pectus excavatum.

Depending on the severity of the deformity and subsequent narrowing of the thoracic cavity, restrictive pulmonary disease may result. A relationship between pectus excavatum and exercise limitation has been reported in some patients. Right ventricular performance may also be adversely affected by this anomaly (Mocchegiani et al. 1995). Pectus excavatum may be associated with segmental bronchomalacia. The psychological impact of this aesthetically unat-

Fig. 2.10 a, b. Isolated thoracic dysostosis in a 5-year-old boy. a Posteroanterior and b lateral chest films show that the ribs are short anteriorly, and wavy and underdeveloped posteriorly. The upper thorax is constricted, giving the chest cage a triangular (bell-shaped) configuration. A pectus excava-tum deformity is evident. Observe the pulmonary infiltrate in the posterior basilar segment of the left lower lobe. (Reprinted, with permission, from Rabushka et al. 1973)

Pectus ExcavatumPectus Excavatum
Fig. 2.11. Schwartz-Jampel syndrome in a 7-year-old boy. Observe mild depression of lower sternum

tractive deformity can be considerable (Ellis 1989) and is the single most common reason for requesting surgical repair (Myers 1991).

Congenital isolated pectus excavatum (OMIM 169300) has long been recognized as an anomaly occurring on a familial basis (Nowak 1936). Autosomal dominant inheritance with instances of male-tomale transmission has been reported (Leung and Hoo 1987). An autosomal dominant association of Pierre Robin sequence (micrognathia, glossoptosis, cleft palate) with pectus excavatum and rib/scapular anomalies (OMIM 602196) has been reported in a family over five generations (Stalker and Zori 1997). The severity of the pectus deformity varied from moderate to severe. The rib defects included single dysplastic rib and eleven pairs of ribs, while the scapular defect consisted of hypoplasia of the inferior subscapular area. Another association probably transmitted by an autosomal dominant inheritance comprises pectus excavatum, macrocephaly, short stature, and dysplastic nails (OMIM 600399) (Zori et al. 1992). Isolated malformation of the thoracic cage, known as thoracic dysostosis (OMIM 187750), involves short and deformed ribs similar to those of Melnick-Needles syndrome and pectus excava-tum, resulting in a constricted, bell-shaped thorax (Fig. 2.10 a,b). Pulmonary function can be adversely affected in this condition (Rabushka et al. 1973). Anterior chest deformity, including pectus excavatum and carinatum, is a cardinal feature of Marfan syndrome (OMIM 154700), a disorder characterized by joint laxity, scoliosis, increased height, disproportionately long limbs and digits, and arched palate. Pectus excavatum occurs in about 70% of patients affected. Compared with isolated pectus excavatum, the deformity associated with Marfan syndrome manifests later in life, is progressive (Golladay et al. 1985), and tends to recur after surgical repair (Arn et al. 1989). Certain features of this disorder, including those with high diagnostic value, such as the doli-chostenomelia and arachnodactyly, as well as the anterior chest wall deformities, can be explained as excessive longitudinal growth of the parent bones. Excessive longitudinal growth might in turn be related to a defect in the fibrous elements of the periosteum (McKusick 1956). The pulmonary function in these patients may be compromised by a restrictive venti-latory defect caused by pectus excavatum and scolio-

sis (Streeten et al. 1987). Obstructive respiratory disease that is most prominent during sleep and caused by upper airway collapsibility and/or increased laxity of the pharyngeal wall may be a complication (Cistul-li and Sullivan 1995; Verbraecken et al. 1995). Pectus excavatum also sometimes accompanies those malformation spectra in which a marfanoid habitus is observed,including marfanoid mental retardation,X-linked type (OMIM 309520) (Lujan et al. 1984) and dominant type (OMIM 248770), microcephaly and glomerulonephritis (OMIM 248760), marfanoid hy-permobility syndrome (OMIM 154750), cutis laxa-marfanoid syndrome (OMIM 150240), and homo-cystinuria (OMIM 2362000) (Visy et al.1991).A shield chest with pectus carinatum superiorly and pectus excavatum inferiarly is characteristic of Noonan syndrome (male Turner-like syndrome, OMIM 163950), an autosomal dominant disorder characterized by short stature, broad forehead, triangular face, ptosis, low-set ears, pterygium colli, low posterior hairline, and congenital heart defects. Kyphoscoliosis, vertebral anomalies (Klippel-Feil,fusion),and limb defects (cubitus valgus, genu valgum, syndactyly, campto-dactyly) are frequent radiologic manifestations. Pectus excavatum also occurs in German syndrome (OMIM 231080), an association of 'arthrogryposis,' hypotonia-hypokinesia sequence, and lymphedema (German et al. 1975) and in the 3M syndrome (OMIM 273750), a dwarfing condition with narrow facies, broad thorax with thin and horizontal ribs, clin-odactyly, and normal intelligence (Miller et al. 1975). Although the most typical thoracic deformity in Schwartz-Jampel syndrome (OMIM 255800) is pectus carinatum, pectus excavatum can also be encountered (Fig. 2.11).

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