Integumentary System — MCQs
The main function of Vitamin C in the body is
A female patient of 26 years, presents with oral ulcers, photosensitivity and skin malar rash in face sparing the nasolabial folds of both side.
A 70-year-old man comes to the emergency department because of a skin rash and severe itching. He appears ill; there is a generalized skin rash that is scaly, erythematous, and thickened. His palms, soles, and scalp are also involved. Which of the following is the most likely diagnosis?
A patient presents with focal alopecia areata. All of the following are associations of alopecia areata except:
Melanocytes are present in which of the following layers of the epidermis?
What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
Langerhans cells in skin fall under which category?
A lady with 50% TBSA burn with involvement of dermis and subcutaneous tissue came to the emergency department. The burns will be classified as:
Stratification-specific keratins present in gingival epithelium are:
Merkel cells are found in which of the following tissues?
Integumentary System Indian Medical PG Practice Questions and MCQs
Question 1: The main function of Vitamin C in the body is
- A. Cofactor for hydroxylation reactions in collagen synthesis (Correct Answer)
- B. Regulation of lipid synthesis
- C. Involvement as antioxidant
- D. Inhibition of cell growth
Explanation: ***Cofactor for hydroxylation reactions in collagen synthesis*** - Vitamin C (ascorbic acid) serves as an essential **cofactor** for **prolyl hydroxylase** and **lysyl hydroxylase** enzymes. - These enzymes catalyze the **hydroxylation of proline and lysine** residues in collagen, forming **hydroxyproline** and **hydroxylysine**. - This hydroxylation is crucial for the **stability and cross-linking** of collagen triple helix structure. - Deficiency leads to **scurvy**, characterized by defective collagen synthesis, bleeding gums, poor wound healing, and bone abnormalities. - This is the **primary and main function** of Vitamin C in the human body. *Involvement as antioxidant* - While Vitamin C does act as a **water-soluble antioxidant**, protecting cells from oxidative damage by free radicals, this is a **secondary function**. - It can donate electrons to neutralize reactive oxygen species and regenerate other antioxidants like Vitamin E. - This protective role is important but not the main function compared to its role in collagen synthesis. *Regulation of lipid synthesis* - Vitamin C is **not directly involved** in the primary pathways of lipid synthesis or metabolism. - It may play a minor role in **carnitine synthesis** (needed for fatty acid oxidation), but this is not a major function. - Other nutrients like B vitamins play more significant roles in lipid metabolism regulation. *Inhibition of cell growth* - Vitamin C does **not inhibit normal cell growth**; it is essential for cell health, differentiation, and tissue repair. - While high doses may have some anti-proliferative effects in certain cancer cell lines in vitro, this is not a physiological function in the healthy body.
Question 2: A female patient of 26 years, presents with oral ulcers, photosensitivity and skin malar rash in face sparing the nasolabial folds of both side.
- A. Sturge weber syndrome
- B. Dermatitis
- C. Psoriasis
- D. SLE (Correct Answer)
Explanation: ***SLE*** - The combination of **oral ulcers**, **photosensitivity**, and a **malar rash** that spares the nasolabial folds is highly characteristic of **Systemic Lupus Erythematosus (SLE)** [1]. - SLE is an autoimmune disease with diverse clinical manifestations involving multiple organ systems. *Sturge weber syndrome* - This is a neurocutaneous disorder characterized by a **port-wine stain** (nevus flammeus) typically on the face, neurological abnormalities like seizures, and ocular involvement. - It does not present with oral ulcers or photosensitivity as primary features. *Dermatitis* - **Dermatitis** is a general term for skin inflammation, often presenting with redness, itching, and sometimes blisters. - It does not typically involve the specific constellation of oral ulcers, photosensitivity, and a malar rash that spares nasolabial folds. *Psoriasis* - **Psoriasis** is a chronic autoimmune disease primarily affecting the skin, characterized by red, scaly patches (plaques) [2]. - While it can cause nail changes and sometimes joint pain, it does not present with photosensitivity, oral ulcers, or the characteristic malar rash described.
Question 3: A 70-year-old man comes to the emergency department because of a skin rash and severe itching. He appears ill; there is a generalized skin rash that is scaly, erythematous, and thickened. His palms, soles, and scalp are also involved. Which of the following is the most likely diagnosis?
- A. erythroderma (exfoliative dermatitis) (Correct Answer)
- B. pemphigus vulgaris
- C. dermatitis herpetiformis
- D. rosacea
Explanation: ***erythroderma (exfoliative dermatitis)*** - Erythroderma is characterized by a **generalized erythematous (red), scaly, and thickened skin rash** covering more than 90% of the body surface, accompanied by **severe itching**. - This condition is often associated with a **systemic illness**, and the patient's description of "appears ill" further supports this diagnosis. *pemphigus vulgaris* - Pemphigus vulgaris typically presents with **flaccid blisters** and erosions, particularly affecting mucous membranes, which are not described here. - While it can be widespread, the primary lesion is a **blister** rather than diffuse erythema and scaling. *dermatitis herpetiformis* - Dermatitis herpetiformis is characterized by intensely **pruritic (itchy) papules and vesicles** typically found on the extensor surfaces (e.g., elbows, knees, buttocks). - It is strongly associated with **celiac disease** and does not present as a generalized scaly, erythematous thickening. *rosacea* - Rosacea primarily affects the **face**, causing **erythema**, flushing, papules, and pustules, often sparing the palms, soles, and scalp. - It is not characterized by generalized scaling, thickening, or severe itching over the entire body.
Question 4: A patient presents with focal alopecia areata. All of the following are associations of alopecia areata except:
- A. Atopy
- B. Exclamatory mark
- C. Nail pitting
- D. Geographic tongue (Correct Answer)
Explanation: ***Geographic tongue*** - **Geographic tongue** (benign migratory glossitis) is a benign inflammatory condition of the tongue and is generally not associated with alopecia areata. - While its exact cause is unknown, it's typically linked to genetic factors or sensitivities rather than autoimmune hair loss. *Atopy* - **Atopy**, including conditions like **eczema**, **asthma**, and **allergic rhinitis**, is a well-established association with alopecia areata, suggesting a shared immune dysregulation. - Patients with alopecia areata often have a higher prevalence of **atopic diathesis**. *Exclamatory mark* - The presence of **exclamatory mark hairs** (short, broken hairs that are narrower near the scalp) is a **pathognomonic sign** of active alopecia areata. - These hairs indicate ongoing inflammation and destruction of the hair follicles. *Nail pitting* - **Nail pitting**, characterized by small depressions in the nail plate, is a common finding in patients with alopecia areata, reflecting an immune-mediated attack on the **nail matrix**. - Other nail changes, such as **trachyonychia** (roughened nails), can also occur.
Question 5: Melanocytes are present in which of the following layers of the epidermis?
- A. Stratum Corneum
- B. Stratum Granulosum
- C. Stratum Basale (Correct Answer)
- D. Stratum Lucidum
Explanation: ***Stratum Basale*** - Melanocytes are found in the **stratum basale** (basal layer) of the epidermis, specifically at the epidermal-dermal junction [1]. - Their primary function is to produce **melanin**, a pigment that protects the skin from UV radiation [1]. *Stratum Corneum* - This is the **outermost layer** of the epidermis, consisting of dead, flattened keratinocytes [1]. - Its main function is to provide a **protective barrier** against the environment. *Stratum Granulosum* - This layer is characterized by cells containing **keratohyalin granules**, which are involved in the process of keratinization. - Melanocytes are not typically found in this layer; it is primarily composed of **keratinocytes in various stages of differentiation**. *Stratum Lucidum* - The stratum lucidum is a **clear, thin layer** found only in thickened skin such as the palms of the hands and soles of the feet. - It is composed of flattened, dead keratinocytes and lacks melanocytes.
Question 6: What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
- A. Amount of saline in graft
- B. Plasma imbibition (Correct Answer)
- C. New vessels growing from the donor tissue
- D. Connection between donor and recipient capillaries
Explanation: ***Correct: Plasma imbibition*** - **Plasma imbibition** is the initial process where the transplanted graft absorbs nutrients and oxygen from the recipient bed through diffusion. - This fluid uptake is crucial for the survival of the graft cells before revascularization occurs, typically within the first **24-48 hours**. - The graft acts like a sponge, absorbing serum and plasma from the vascular bed through capillary action and osmosis. *Incorrect: Amount of saline in graft* - While sterile saline is often used to keep donor tissue moist during harvesting and transport, its presence in the graft itself is not the primary mechanism for survival post-transplantation. - Excessive saline could even lead to **edema** and compromise graft take if not properly drained or if it prevents good contact with the recipient bed. *Incorrect: New vessels growing from the donor tissue* - Grafts themselves do not spontaneously grow new vessels; new blood vessels are formed by **angiogenesis** from the recipient bed into the graft over several days. - This process, called **inosculation** and subsequent neovascularization, provides long-term blood supply but is not the primary mechanism of survival within the *first 48 hours*. *Incorrect: Connection between donor and recipient capillaries* - The direct connection of donor and recipient capillaries (inosculation) is a later stage of graft vascularization, typically beginning after **3-5 days**, not within the first 48 hours. - Within the initial 48 hours, the graft relies on diffusion because a complete vascular connection has not yet been established.
Question 7: Langerhans cells in skin fall under which category?
- A. Keratin synthesising cell
- B. Sensory neurons
- C. Pigment producing cells
- D. Antigen presenting cell (Correct Answer)
Explanation: ***Antigen presenting cell*** - **Langerhans cells** are specialized **dendritic cells** found in the epidermis of the skin and play a crucial role in the immune system [1], [3]. - Their primary function is to capture and process antigens from the skin environment and present them to **T lymphocytes**, initiating an immune response [1], [2]. *Keratin synthesising cell* - **Keratinocytes** are the primary cells responsible for synthesizing **keratin**, providing structural integrity to the epidermis [3]. - Langerhans cells originate from bone marrow and are not involved in keratin production. *Sensory neurons* - **Sensory neurons** (e.g., Merkel cells and nerve endings) are responsible for transmitting sensations like touch, pressure, and pain [3]. - Langerhans cells are immune cells and do not have neuronal functions. *Pigment producing cells* - **Melanocytes** are the cells responsible for producing **melanin**, the pigment that gives skin, hair, and eyes their color [3]. - Langerhans cells do not produce pigment; their role is immune surveillance [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 200. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 174-175. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, p. 1144.
Question 8: A lady with 50% TBSA burn with involvement of dermis and subcutaneous tissue came to the emergency department. The burns will be classified as:
- A. 3rd degree burn (Correct Answer)
- B. 2nd degree superficial
- C. 2nd degree deep
- D. 1st degree
Explanation: ***3rd degree burn*** - **Third-degree burns** involve the entire thickness of the skin (dermis and epidermis) and often extend into the **subcutaneous tissue**, muscle, or bone. - These burns typically appear dry, leathery, and often lack pain sensation due to nerve destruction. *2nd degree superficial* - **Superficial second-degree burns** involve the epidermis and the superficial part of the dermis, often presenting with **blisters** and painful, red, moist skin. - They do not extend to the subcutaneous tissue, which is a key feature of the burn described. *2nd degree deep* - **Deep second-degree burns** involve the epidermis and deeper layers of the dermis, but not the entire dermis or subcutaneous tissue. - While they can be less painful and appear dry, the involvement of **subcutaneous tissue** pushes the classification to third-degree. *1st degree* - **First-degree burns** only affect the epidermis, causing redness and pain but **no blistering** or damage to deeper layers. - These are typically sunburns or minor scalds and do not involve the dermis or subcutaneous tissue.
Question 9: Stratification-specific keratins present in gingival epithelium are:
- A. K16, K6
- B. K1, K2
- C. K10, K12
- D. K5, K14 (Correct Answer)
Explanation: ***K5, K14*** - **Keratins 5 and 14** are typically found in the **basal layer** of stratified squamous epithelia, including the gingival epithelium, indicating their role in maintaining structural integrity. - They are considered **"basal keratins"** and are fundamental for the initial stratification and proliferation of epithelial cells. *K1, K2* - **Keratins 1 and 2** are characteristic of **terminally differentiated, keratinized epithelia**, such as in the epidermis of the skin, not primarily the basal or proliferating layers of gingival epithelium. - While gingiva can be keratinized, K1 and K2 are typically found in the more superficial layers of heavily keratinized tissues, not as stratification-specific markers for the entire epithelium. *K10, K12* - **Keratin 10** is found in **suprabasal layers** of keratinized epithelia, playing a role in the formation of the cornified envelope. While gingiva may be keratinized, K10 is not specifically a "stratification-specific" keratin in the same foundational sense as K5/K14. - **Keratin 12** is primarily expressed in the **corneal epithelium**, making it highly specific to that tissue and not generally found in gingival epithelium. *K16, K6* - **Keratins 6 and 16** are typically expressed in **proliferative epithelia** or in conditions of hyperproliferation, wound healing, or certain pathological states. - While they can be found in gingiva under certain circumstances (e.g., inflammation), they are not considered the primary "stratification-specific" keratins in healthy, normal gingival epithelium involved in regular stratification.
Question 10: Merkel cells are found in which of the following tissues?
- A. Reticular layer of dermis
- B. Epidermis (Correct Answer)
- C. Hypodermis
- D. Papillary layer of dermis
Explanation: ***Epidermis*** - **Merkel cells** are specialized **neuroendocrine cells** located in the **stratum basale** (deepest layer) of the epidermis [1]. - They function as **mechanoreceptors**, playing a crucial role in **touch sensation**, particularly light touch and discrimination of shapes and textures [1]. *Reticular layer of dermis* - The **reticular layer** is the deeper, thicker layer of the dermis, composed of dense irregular connective tissue. - It primarily contains **collagen and elastic fibers** and is involved in the skin's strength and elasticity, not housing mechanoreceptors like Merkel cells. *Hypodermis* - The **hypodermis** (or superficial fascia) is the layer beneath the dermis, primarily composed of **adipose tissue** and loose connective tissue. - Its main functions include **insulation**, energy storage, and shock absorption; it does not contain Merkel cells. *Papillary layer of dermis* - The **papillary layer** is the superficial layer of the **dermis**, characterized by dermal papillae that interdigitate with the epidermis. - While it contains touch receptors like **Meissner's corpuscles**, it does not contain Merkel cells, which are epidermal.
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