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Questions and Answers
Which cell type in the epidermis is responsible for the production of melanin?
Which cell type in the epidermis is responsible for the production of melanin?
What is the primary function of the integumentary system?
What is the primary function of the integumentary system?
Which layer of the skin contains collagen, elastin, and reticulin?
Which layer of the skin contains collagen, elastin, and reticulin?
What is the main constituent of hair and nails?
What is the main constituent of hair and nails?
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Which cell type in the epidermis is involved in presenting antigens to helper T cells?
Which cell type in the epidermis is involved in presenting antigens to helper T cells?
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Which accessory structure is NOT part of the integumentary system?
Which accessory structure is NOT part of the integumentary system?
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What is the function of Merkel cells in the epidermis?
What is the function of Merkel cells in the epidermis?
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Which type of skin cancer is most frequently observed, accounting for approximately 85% of nonmelanoma skin cancers?
Which type of skin cancer is most frequently observed, accounting for approximately 85% of nonmelanoma skin cancers?
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What is the primary factor contributing to the increasing rates of nonmelanoma skin cancer in Canada and the US?
What is the primary factor contributing to the increasing rates of nonmelanoma skin cancer in Canada and the US?
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Which type of skin cancer is more likely to invade other tissue and cause death?
Which type of skin cancer is more likely to invade other tissue and cause death?
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What is the primary cause of UVR-induced DNA damage?
What is the primary cause of UVR-induced DNA damage?
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What is the function of p53 in response to excessive UV-induced DNA damage?
What is the function of p53 in response to excessive UV-induced DNA damage?
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What is the consequence of inactivated tumor suppressor genes in the context of cancer development?
What is the consequence of inactivated tumor suppressor genes in the context of cancer development?
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How many hits are required to inactivate the two alleles of a tumor suppressor gene?
How many hits are required to inactivate the two alleles of a tumor suppressor gene?
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What is the primary factor contributing to the increasing rates of nonmelanoma skin cancer in Canada and the US?
What is the primary factor contributing to the increasing rates of nonmelanoma skin cancer in Canada and the US?
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What is the primary cause of UVR-induced DNA damage?
What is the primary cause of UVR-induced DNA damage?
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Which skin infection is caused by dermatophytes and Candida albicans?
Which skin infection is caused by dermatophytes and Candida albicans?
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What is the impact of UVB rays on the skin?
What is the impact of UVB rays on the skin?
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Which type of skin infection is caused by pathogens like Staphylococcus aureus and Streptococci?
Which type of skin infection is caused by pathogens like Staphylococcus aureus and Streptococci?
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What is the process that converts 7-dehydrocholesterol in the skin into previtamin D3?
What is the process that converts 7-dehydrocholesterol in the skin into previtamin D3?
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What is the main function of cutaneously synthesized vitamin D3?
What is the main function of cutaneously synthesized vitamin D3?
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How is dietary vitamin D2 and D3 processed in the liver?
How is dietary vitamin D2 and D3 processed in the liver?
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What is the impact of sunscreen on the levels of 25-hydroxyvitamin D?
What is the impact of sunscreen on the levels of 25-hydroxyvitamin D?
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Which of the following skin disorders is characterized by T cell immune-mediated thick, silvery, elevated lesions?
Which of the following skin disorders is characterized by T cell immune-mediated thick, silvery, elevated lesions?
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What type of hypersensitivity reaction is urticaria (hives) caused by?
What type of hypersensitivity reaction is urticaria (hives) caused by?
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What is the primary factor influencing the development of acne vulgaris?
What is the primary factor influencing the development of acne vulgaris?
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Which skin disorder involves the development of papules, scales, plaques, and erythema?
Which skin disorder involves the development of papules, scales, plaques, and erythema?
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What is the primary characteristic of dermatitis?
What is the primary characteristic of dermatitis?
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What is the role of TNF-a in psoriasis?
What is the role of TNF-a in psoriasis?
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Which skin disorder is characterized by noninflammatory and inflammatory lesions such as blackheads, whiteheads, and cystic nodules?
Which skin disorder is characterized by noninflammatory and inflammatory lesions such as blackheads, whiteheads, and cystic nodules?
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What is the primary focus of the second article in the continuing medical education series mentioned in the text?
What is the primary focus of the second article in the continuing medical education series mentioned in the text?
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What is the main finding regarding orobol's impact on cutaneous squamous cell carcinoma (cSCC) in the mouse model mentioned in the text?
What is the main finding regarding orobol's impact on cutaneous squamous cell carcinoma (cSCC) in the mouse model mentioned in the text?
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What is the suggested clinical approach for preventing and treating the development and regrowth of cutaneous squamous cell carcinoma (cSCC) based on the findings related to orobol in the text?
What is the suggested clinical approach for preventing and treating the development and regrowth of cutaneous squamous cell carcinoma (cSCC) based on the findings related to orobol in the text?
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Which subset of helper cells is proposed as a repository of disease memory in sites of recurrent psoriasis?
Which subset of helper cells is proposed as a repository of disease memory in sites of recurrent psoriasis?
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Which T cell subset is found to play significant roles in the pathogenesis of psoriasis?
Which T cell subset is found to play significant roles in the pathogenesis of psoriasis?
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What is the emerging role of CD4 T cells in the clinical manifestations of psoriasis and associated comorbidities?
What is the emerging role of CD4 T cells in the clinical manifestations of psoriasis and associated comorbidities?
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Which T cell subset is linked to the action of IL-22 on keratinocytes in psoriasis?
Which T cell subset is linked to the action of IL-22 on keratinocytes in psoriasis?
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Which subset of helper cells is associated with the IL-23/Th17 axis in psoriasis?
Which subset of helper cells is associated with the IL-23/Th17 axis in psoriasis?
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Study Notes
Skin Disorders Overview
- The subcutaneous layer consists of fat cells organized into lobules by fibrous walls of collagen and large blood vessels.
- Clinical manifestations of skin dysfunction include various types of lesions such as nodules, tumors, vesicles, bullae, pustules, cysts, telangiectasia, scales, lichenification, keloid scars, excoriations, fissures, erosions, ulcers, and atrophy.
- Inflammatory skin disorders encompass dermatitis, which is a general term for skin inflammation characterized by pruritus, lesions with indistinct borders, and epidermal changes, and includes types such as atopic dermatitis, allergic contact dermatitis, non-allergic contact dermatitis, irritant contact dermatitis, stasis dermatitis, and seborrheic dermatitis.
- Hypersensitivity reactions, including allergic contact dermatitis, are mediated by immune mechanisms and result in manifestations such as erythema, swelling, pruritus, and vesicular lesions.
- Urticaria, or hives, is caused by type I hypersensitivity reactions to allergens, leading to endothelial cell contraction and fluid leakage from vessels, typically treated with antihistamines and steroids.
- Papulosquamous disorders involve the development of papules, scales, plaques, and erythema, including conditions such as psoriasis, pityriasis rosea, lichen planus, acne vulgaris, acne rosacea, and lupus erythematosus.
- Psoriasis is a chronic, non-contagious, autoimmune skin disorder characterized by T cell immune-mediated thick, silvery, elevated lesions, with evidence of dermal and epidermal thickening and altered skin cell growth and differentiation.
- In psoriasis, dendritic cells in the skin play a role in the immune response, presenting antigens to T cells, leading to the release of cytokines and chemokines, recruitment of neutrophils, and hyperplasia of keratinocytes.
- TNF-a is produced in excess amounts by activated T cells in people with psoriasis and psoriatic arthritis, leading to rapid skin cell growth and joint symptoms, with biologic medications targeting TNF-a and T cells.
- Acne vulgaris encompasses noninflammatory acne, caused by factors such as follicular plugging, excessive sebum production, and colonization of Propionibacterium acnes, as well as inflammatory acne, resulting from follicular wall rupture and deeper inflammation, which may cause scarring.
- Acne vulgaris is influenced by physiologic factors such as plugging of folliculosebaceous units, follicular hyperkeratinization, excessive sebum production, and inflammation secondary to the action of inflammatory products produced by P. acnes.
- The manifestations of acne vulgaris include noninflammatory and inflammatory lesions, such as blackheads, whiteheads, and cystic nodules.
T Cell Subsets and Their Roles in Psoriasis
- Different subsets of helper cells contribute to the pathogenesis of psoriasis, with the IL-23/Th17 axis playing a central role in amplifying inflammation and cutaneous manifestations.
- Th1 cells likely participate in the early stages of psoriasis pathogenesis by inducing CCL20 and IL-23 production by myeloid dendritic cells.
- Tissue resident Th22 and CD8 Tc17 cells are proposed as repositories of disease memory in sites of recurrent psoriasis, linked to prominent histological features of the disease due to the action of IL-22 on keratinocytes.
- IL-9-producing Th9 cells have been found to play significant roles in the pathogenesis of psoriasis.
- CD4 T cells recirculating between the skin and blood have an emerging role in the clinical manifestations of psoriasis and associated comorbidities.
- CCR4+ CD4 and CD8 T cells may amplify skin and systemic inflammation in psoriasis, respectively.
- Further investigations are needed to elucidate the connection between T cell responses in the skin and the comorbidities associated with psoriasis.
- The authors declare no competing interests in the research.
- The IL-23/T17 pathogenic axis in psoriasis is amplified by keratinocyte responses.
- Th17 and Th22 cells have been identified in psoriatic arthritis and psoriasis.
- A novel proinflammatory human skin-homing V𝛾9V𝛿2 T cell subset has been identified with a potential role in psoriasis.
- Laser capture microdissection and cDNA microarray analysis have identified locally expressed disease-related genes in focal regions of psoriasis vulgaris skin lesions.
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Description
Test your knowledge of skin disorders with this overview quiz. Learn about inflammatory skin conditions, hypersensitivity reactions, papulosquamous disorders, and more.
