WBR0294

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathophysiology
Sub Category	SubCategory::Dermatology
Prompt	[[Prompt::A 46-year-old African-American man presents to the physician's office for an abdominal lesion. He explains that he was involved in a fire accident 3 months ago and sustained a third-degree burn to the periumbilical area. As his wound was healing, he noticed the abnormal formation of scar tissue at the wound site (shown below). The patient also states that he has similar scar tissue that developed during healing of other wounds. What type of tissue is involved in the formation of this patient's scar? ]]
Answer A	AnswerA::Type II collagen
Answer A Explanation	AnswerAExp::Cartilage, vitreous body of the eye, and nucleus pulposus are all examples of type II collagen.
Answer B	AnswerB::Type III collagen
Answer B Explanation	AnswerBExp::Both hypertrophic scars and keloids are mainly formed of type III collagen.
Answer C	AnswerC::Type IV collagen
Answer C Explanation	AnswerCExp::Basement membranes, basal lamina, and lens are all examples of type IV collagen.
Answer D	AnswerD::Type VIII collagen
Answer D Explanation	AnswerDExp::Type VIII collagen is a less abundant type of collagen that is present in some endothelial cells, mast cells, and keratinocytes. Examples of type VIII collagen are not high yield for USMLE Step 1.
Answer E	AnswerE::Type X collagen
Answer E Explanation	AnswerEExp::Type X collagen may be present in cartilage. Examples of type X collagen are not high yield for USMLE Step 1.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The formation of hypertrophic scars and keloids results from the uncontrolled tissue repair and abnormal fibrous healing process of a wound. Patients with hypertrophic scars and keloids often present with cosmetic concerns, although the lesions may be pruritic or painful in the minority of cases. Although both hypertrophic scars and keloids are similarly the result of impaired repair process of the regeneration-regulating mechanism, they are clinically distinct and are managed differently. Thus, distinction between the 2 is crucial for optimal management. Educational Objective: Both hypertrophic scars and keloids are mainly formed of type III collagen. References: Shuttleworth CA. Type VIII collagen. Int J Biochem Cell Biol. 1997;29(10):1145-8. Shen G. The role of type X collagen in facilitating and regulating endochondral ossification of articular cartilage. Orthod Craniofac Res. 2005;8(1):11-7. Wolfram D, Tzankov A, Pülzl P, et al. Hypertrophic scars and keloids - a review of their pathophysiology, risk factors, and therapeutic management. Dermatol Surg. 2009;35(2):171-81. Image: "Keloid, Trunk.JPG" by user:Htirgan, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license. http://commons.wikimedia.org/ retrieved 1-Jan-2015. First Aid 2014 page 225]]
Approved	Approved::Yes
Keyword	WBRKeyword::Keloid, WBRKeyword::Hypertrophic Scar, WBRKeyword::Scar, WBRKeyword::Collagen, WBRKeyword::Type III collagen, WBRKeyword::Scar formation, WBRKeyword::Burn, WBRKeyword::African-American
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