A 23-year-old man comes to the office due to a painful, growing lesion on his chest. The patient reports a laceration injury to the chest 6 months ago. A pink, firm plaque on examination is shown in the image below: Which of the following is most likely responsible for this patient's lesion?

Question

A 23-year-old man comes to the office due to a painful, growing lesion on his chest.  The patient reports a laceration injury to the chest 6 months ago.  A pink, firm plaque on examination is shown in the image below:  Which of the following is most likely responsible for this patient's lesion?

Quizplus · Accepted Answer

This patient with a painful, growing lesion at the site of a prior injury likely has a keloid. Keloids and hypertrophic scars consist of connective tissue rich in fibroblasts, myofibroblasts, and bundles of collagen fibers and result from excessive collagen formation during the remodeling phase of wound healing, which typically occurs between 3 weeks and 2 years after an injury. The abundant collagen fibers are arranged in a disorganized fashion in keloids and parallel in hypertrophic scars. Normally, during the proliferation phase of wound healing, fibroblasts proliferate, synthesize collagen and ground substance, and differentiate into myofibroblasts. These processes are promoted by transformation growth factor beta (TGF beta), which typically diminishes upon completion of wound repair, when the wound transitions to the maturation phase. In keloids, however, TGF beta is overexpressed, with little regulation. As a result, keloids extend beyond the borders of the original wound, do not regress, and often recur after resection. In contrast, hypertrophic scars are limited to the original wound borders and may regress spontaneously. Keloids can have a familial tendency, particularly in individuals of Asian or African ethnicity. They are often raised and painful/pruritic and are usually diagnosed clinically. (Choices A and B) Increased (vs decreased) activity of other factors that promote tissue growth and wound healing (eg, insulin-like growth factor 1, platelet-derived growth factor [PDGF]) are thought to contribute to keloid formation. (Choice C) In addition to increased fibroblast proliferation in response to TGF beta, a decreased (vs increased) fibroblast apoptosis rate may contribute to the greater number of fibroblasts (and subsequent increased collagen production) seen in keloids. (Choice E) Matrix metalloproteinases (MMP) contribute to tissue remodeling through degradation of the extracellular matrix, typically in a regulated fashion. Decreased MMP activity (leading to decreased extracellular matrix degradation) may contribute to keloid formation. In contrast, MMP overproduction is often present in chronic (ie, nonhealing) wounds. Educational objective: Keloids result from excessive collagen formation during the remodeling phase of wound healing, which occurs due to overexpression of transformation growth factor beta and excessive fibroblast proliferation. They typically present as raised, painful, and pruritic lesions that grow beyond the original wound borders. __________ References: The keloid disorder: heterogeneity, histopathology, mechanisms and models. (http://www.ncbi.nlm.nih.gov/pubmed/32528951)

A 23-Year-Old Man Comes to the Office Due to a Painful