Pectus Carinatum

► [Ventral protrusion of the sternum and its costal cartilages]

Pectus carinatum, or pigeon breast, is characterized by ventral protrusion of the sternum with bilateral flattening of the lateral walls of the chest. The incidence of this deformity is only 1/10th that of pectus excavatum, although in other series a pectus carina-

tum/excavatum distribution of 1.4:1 has been reported (Pena et al. 1981). Pectus carinatum is more common in boys than in girls, is usually diagnosed in children aged 4-5 years, and becomes more prominent during adolescence.

Although bronchopulmonary changes have been observed in both pectus carinatum and pectus exca-vatum, possibly reflecting a primary pulmonary defect, they are clinically relevant only in the latter condition, perhaps because of the superimposition of mechanical compression (Pena et al. 1981). In the majority of patients with pectus carinatum deformity the ventilatory function is preserved and the deformity is mainly a cosmetic and psychological problem (Ellis 1989). Furthermore, compared with pectus excavatum, treatment in pectus carinatum either is more often conservative or provides better results (Vidal et al. 1977; Ottolenghi and Vecchioni 1981).

Based on the location of the apex of the protrusion, three types of pectus carinatum have been described: superior, inferior, and lateral (Haje et al. 1999). The endochondral growth of the sternum and costal cartilage is regarded as a key element in the development of anterior chest wall deformities. In pectus carinatum superior type early fusion of the growth plates in the sternum leads to a disproportion between the arrested growth in the sternum and the normal growth in the costal cartilages. The result is that the sternum is abnormally short, with forward protrusion of its upper portion and inward depression of its inferior portion (Fig. 2.12 a,b). The costal cartilages are elongated and vertically oriented. A similar pattern of sternal deformity occurs in Cur-rarino-Silverman syndrome (premature closure of sternal sutures, OMIM 184800) (Currarino and Silverman 1958). Associated manifestations include mi-crognathia, cryptorchidism, and congenital heart defect. This sternal deformity is also characteristic of Noonan syndrome (OMIM 163950). The pathogenesis of pectus carinatum inferior type is more controversial (Fig. 2.13). Hypoplasia of the inferior segments of the sternum while the costal cartilages continue to grow can lead to forward protrusion of the inferior sternum, with lateral depressions (Harrison grooves) representing inward bending of the costo-chondral junctions. Alternatively, overgrowth of the lowest costal arches may produce comparable effects. In the lateral type of pectus carinatum, a developmental asymmetry of the sternum may result in rotation of the sternum along its longitudinal axis, thus producing the sternal protrusion and ultimately the contralateral parasternal depression at the level of the costal cartilages (Haje et al. 1999).

Fig.2.12a,b. Pectus carina-tum, superior type in a boy a at 2 months and b at 8 years of age. At 2 months the inferior sternal growth plates are closed, whereas the superior sternal body growth plate and the manubrium-sternal growth plate are narrowed. By 8 years of age complete fusion of all the growth plates has occurred; the sternum is short and anteriorly bowed

Superior Pectus Carinatum Fotos

Fig.2.12a,b. Pectus carina-tum, superior type in a boy a at 2 months and b at 8 years of age. At 2 months the inferior sternal growth plates are closed, whereas the superior sternal body growth plate and the manubrium-sternal growth plate are narrowed. By 8 years of age complete fusion of all the growth plates has occurred; the sternum is short and anteriorly bowed

Growth Plates Sternum

Fig. 2.13. Pectus carinatum, inferior type in a 5-year-old girl. Note short inferior segments of the sternal body (arrows) and ossified xiphoid process. The most superior sternal body segment was of normal height, while the inferior segments were found on MRI study (not shown) to be irregular and hypoplastic. (From Haje et al. 1999)

Fig. 2.13. Pectus carinatum, inferior type in a 5-year-old girl. Note short inferior segments of the sternal body (arrows) and ossified xiphoid process. The most superior sternal body segment was of normal height, while the inferior segments were found on MRI study (not shown) to be irregular and hypoplastic. (From Haje et al. 1999)

Like pectus excavatum, pectus carinatum also occurs most commonly as an isolated anomaly, but it can also be seen in conjunction with other skeletal or visceral anomalies. In a series of 152 patients with pectus carinatum requiring surgical correction, associated musculoskeletal abnormalities were found in 34 (scoliosis in 23, Poland syndrome in 4, neurofibro-matosis type 1 in 2, Morquio disease in 2, vertebral anomalies, hyperlordosis, and kyphosis in 1 case each). A family history of chest wall deformities was present in 26% of the patients, and familial scoliosis in 12% (Shamberger and Welch 1987). Congenital heart defects (Iakovlev et al. 1990) and diaphragmatic hernias (Soylu et al. 2000) are associated with a higher frequency than is found in the general population. Multiple skeletal abnormalities, including pectus carinatum or excavatum, acetabular dyspla-sia, and bowed long bones, together with short stature, myotonia, expressionless face, myopia, ble-pharophimosis, joint contractures, and spinal mal-alignment, are manifestations of Schwartz-Jampel syndrome (OMIM 255800), an autosomal recessive disorder (Aberfeld et al. 1965; Schwartz and Jampel 1962). Early diagnosis and treatment with carba-mazepine can resolve myotonia and prevent the development of classic skeletal anomalies (pectus cari-natum, stiff joints, bowed bones) (Squires and Pran-gley 1996). Prune-belly sequence (OMIM 100100) displays several musculoskeletal abnormalities, including clubfeet, limb deficiencies, hip dysplasia, vertebral malformations, scoliosis, and pectus exca-vatum and/or carinatum (Loder et al. 1992). In Cof-fin-Lowry syndrome (OMIM 303600) either pectus carinatum or pectus excavatum may be seen, together with a short sternum and thoracic kyphosis. These deformities can also occur in Marfan syndrome (OMIM 154700) (Magid et al. 1990) and homocyst-inuria. In mucopolysaccharidosis type VII (OMIM 253220), a disorder with beta glucuronidase deficiency, pectus carinatum, gross thoracic kyphoscoliosis, and hip dysplasia are features (de Kremer et al. 1992). An association of pectus carinatum, joint laxity, and a characteristic facies (frontal bossing, low nasal bridge, malar hypoplasia, parrot-like nose, and arched upper lips) has been observed in a brother and sister (Guizar-Vazquez et al. 1980). Another asso ciation, SCARF syndrome (OMIM 312830), includes skeletal abnormalities, cutis laxa, ambiguous genitalia, retardation of mental development, and facial abnormalities. Distinguishing skeletal abnormalities are pectus carinatum, craniosynostosis, joint hyper-extensibility, and abnormally shaped vertebrae (Koppe et al. 1989). Sternum carinatum has been reported, together with scoliosis, long slender fingers, camptodactyly, cryptorchidism, hypertonia, myopia, and mildly dysmorphic facies, in children with the rare deletion of chromosome 2p11-p13 (Wenger and McPherson 1997). It can be also found in a number of chromosome imbalances and aneuploidies, including trisomy 14 mosaicism (Petersen et al. 1986). Pec-tus carinatum, together with brachycephaly, large and poorly structured ears, strabismus, mild scolio-sis, growth retardation, and severe hypoplasia of the right cerebellar hemisphere and vermis, has been described in a 4-year-old boy with congenital hypothyroidism (Mauceri et al. 1997). Pectus carinatum can also occur as a manifestation of Setleis syndrome (OMIM 227260), a rare autosomal dominant or recessive disorder characterized by a characteristic 'coarse' face, bitemporal 'forceps marks,' skin aplasia and discoloration, sparse hair, short palpebral fissures, conical teeth, and aberrant distal palmar creases (Tsukahara et al. 1995). Acquired, progressive pec-tus carinatum deformity has been described after cardiac surgery in infancy (Haje 1995).

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