[The morphological and morphometric study of amianthoid transformation of the costal cartilage in health and in keeled chest deformity in children]

Amianthoid transformation of costal cartilage matrix in children with pectus excavatum and pectus carinatum

Background

It is unclear if amianthoid transformation (AT) of costal cartilage extracellular matrix (ECM) has an impact on the development of pectus excavatum (PE) and pectus carinatum (PC).

Methods

AT foci were examined in intrasurgical biopsy specimens of costal cartilages of children (8–17 years old) with PE (n = 12) and PC (n = 12) and in age-matching autopsy control samples (n = 10) using histological and immunohistochemical staining, atomic force and nonlinear optical microscopy, transmission and scanning electron microscopy, morphometry and statistics.

Results

AT areas were identified in the costal cartilage ECM in children with normal chest, PE and PC. Each type of the AT areas (“canonical”, “intertwined”, “fine-fibred” and “intralacunary”) had a unique morphological pattern of thickness and alignment of amianthoid fibers (AFs). AFs were formed via lateral aggregation of collagen type II fibrils in the intact ECM. Foci of the AT were observed significantly more frequently in the PE and PC groups. The AT areas had unique quantitative features in each study group.

Conclusion

AT is a structurally diverse form of ECM alteration present in healthy and pathological costal cartilage. PE and PC are associated with specific AT disorders.

[Costal cartilage changes in children with pectus excavatum and pectus carinatum]

Pectus excavatum (PE) and pectus carinatum (PC) in children are the most common congenital deformities that cause complications in the thoracic organs; however, the role of chondrocytes and cartilage canals in the pathogenesis of these conditions remains unexplored.

OBJECTIVE

To investigate qualitative and quantitative changes of cartilage lacunae and canals in the costal cartilages in children with PE and PC compared to those with normal chests.

SUBJECT AND METHODS

Costal cartilages were investigated in 10 children with normal chests (a control group), in 12 children with PE, and in 12 children with PC. Tissue fragments were fixed in 10% neutral formalin and embedded in compacted paraffin. Sections were stained with hematoxylin and eosin. Slides were examined by light microscopy. Cartilage lacunae, hyper- and hypolacunar zones, and cartilage canals were morphometrically examined, followed by statistical data analysis.

RESULTS

There was a significant decrease in the number of cartilage lacunae and in the frequency of hyperlacunar zones and an increase in that of hypolacunar zones in the PE and PC groups. There were no significant differences in these parameters between the PE and PC groups; however, there was a tendency to the smallest number of cartilage lacunae and canals in the PC group and that to the preponderance of empty lacunae in the PE group. Only the PC group showed also negative correlations between the proportions of empty lacunae and the age of children.

CONCLUSION

The pathogenesis of PE and PC in children is related to the impaired trophism of costal cartilages due to the smaller number of cartilage channels containing vessels and lacunae with chondrocytes. The development of PE and PC is associated with specific costal cartilage morphological changes that suggest that PE and PC are different manifestations of the same disease, namely connective tissue dysplasia.

[Costal cartilage structural and functional changes in children with a funnel or keeled chest]

Congenital chest wall deformities (CCWDs) in children are severe diseases leading to cosmetic defects and diseases of the respiratory and cardiovascular systems. The most common of these deformities are funnel-shaped (pectus excavatum, FD) and keeled (pectus carinatum, KD) ones. The pathogenesis of CCWDs and the role of costal cartilage structural and functional changes in their pathogenesis have now been not well studied, which makes it difficult to elaborate pathogenetic approaches to correcting these diseases. Analysis of the literature has shown that structural and functional changes occur in the matrix and chondrocytes from the costal cartilage in FD. Similar costal cartilage changes are observed in KD. It is still unknown exactly which pathological processes are present in the costal cartilage and how they result in the development of one or other type of CCWDs. The role of amianthoid transformation (AT) of costal cartilages in these processes is also unknown. It is not improbable that it is AT drastically changing the native cartilage matrix, which is one of the key mechanisms leading to changes in its properties and to the subsequent development of FD or KD.