A 38-year-old woman presents with a painless lesion on her right ear lobe (shown in the figure). She reports that her ears were pierced 5 months ago. Which of the following best explains the pathogenesis of this lesion?
1.Increased growth of capillary endothelial cells
2.Exuberant formation of granulation tissue
3.Clonal expansion of smooth muscle cells
4.Maturation arrest of collagen assembly
5.Increased turnover of extracellular matrix proteoglycans
Solution
Keloid is an exuberant scar that tends to progress beyond the site of initial injury and recurs after excision. Dark-skinned persons are more frequently affected by keloids than light-skinned people. Keloids are characterized by changes in the ratio of type III to type I collagen, suggesting a “maturation arrest” in the healing process. Further support for maturation arrest as an explanation for keloids and hypertrophic scars is the overexpression of fibronectin in these lesions. Keloids are unsightly, and attempts at surgical repair are always problematic. The other choices do not address the pathogenesis of keloids.