Structure and Function of Skin — MCQs
Anagen phase of the hair indicates-
A patient presents with focal alopecia areata. All of the following are associations of alopecia areata except:
Langerhans cells in skin fall under which category?
Stratification-specific keratins present in gingival epithelium are:
Identify the skin condition depicted in the image.
Dyskeratosis refers to which of the following?
Baby born with membrane around him at the time of birth. Which of the following conditions is depicted?
Acanthosis nigricans is characterized by all of the following except?
Which of the following statements is true regarding Acanthosis Nigricans?
A child is presenting with erythematous follicular papules on the trunk. There are areas of normal skin within the lesions. There is thickening of palms and soles. This child is suffering from -
Structure and Function of Skin Indian Medical PG Practice Questions and MCQs
Question 1: Anagen phase of the hair indicates-
- A. The phase of degeneration
- B. The phase of resting
- C. The phase of activity and growth (Correct Answer)
- D. The phase of transition
Explanation: ***The phase of activity and growth*** - The **anagen phase** is the active growth phase of hair follicles, where cells in the hair matrix rapidly divide and differentiate to form the hair shaft. - During this phase, which can last for several years, hair grows significantly, with the average duration being **2-7 years for scalp hair**. - This is the longest phase of the hair growth cycle, and approximately **85-90% of scalp hairs** are in anagen at any given time. *The phase of degeneration* - This description corresponds to the **catagen phase**, where hair growth ceases and the hair follicle shrinks, signaling the end of the active growth period. - During catagen, the outer root sheath detaches from the dermal papilla, and the hair follicle undergoes controlled regression. - This is a brief phase lasting only **2-3 weeks**. *The phase of resting* - This phase is known as the **telogen phase**, during which the hair follicle is completely at rest, and the old hair is eventually shed. - Telogen is a relatively quiescent period, typically lasting about **3-4 months**, before the follicle re-enters the anagen phase. - Approximately **10-15% of scalp hairs** are in telogen at any given time. *The phase of transition* - This also refers to the **catagen phase**, which serves as a brief transitional period between the active growth (anagen) and resting (telogen) phases. - The term "transition" accurately describes catagen's role as an intermediate stage in the hair growth cycle.
Question 2: 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 3: 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 4: 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 5: Identify the skin condition depicted in the image.
- A. Ichthyosis (Correct Answer)
- B. Syndromic ichthyosis
- C. Cutaneous sarcoidosis
- D. Leprosy
Explanation: ***Ichthyosis*** - The image clearly displays widespread **dry, scaling, and thickened skin**, consistent with the characteristic presentation of ichthyosis. - This condition is characterized by a defect in **skin barrier function** leading to excessive dryness and accumulation of scales. *Syndromic ichthyosis* - While syndromic ichthyosis also involves skin scaling, it is associated with **additional systemic symptoms** or **organ involvement**, which cannot be determined from this image alone. - The term "ichthyosis" broadly covers this appearance, and without more clinical information, specifying it as syndromic is not the most direct identification. *Leprosy* - Leprosy typically presents with **hypopigmented, anesthetic skin patches** or **nodules**, which are not seen in the image. - The texture and color changes in the image are not characteristic of the primarily neurological and dermatological manifestations of leprosy. *Cutaneous sarcoidosis* - Cutaneous sarcoidosis manifests as **reddish-brown papules, plaques, or nodules**, often on the face, neck, or extremities. - The widespread, fine scaling and dryness seen in the image do not align with the typical granulomatous lesions of sarcoidosis.
Question 6: Dyskeratosis refers to which of the following?
- A. Abnormal, premature keratinization within cells below the stratum granulosum. (Correct Answer)
- B. Discontinuity of the skin showing incomplete loss of epidermis.
- C. Keratinization with retained nuclei in the stratum corneum.
- D. Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.
Explanation: ***Abnormal, premature keratinization within cells below the stratum granulosum.*** - **Dyskeratosis** is a histological term for **premature keratinization** of individual keratinocytes. - This typically occurs in cells that are *below* the **stratum granulosum**, often in the stratum spinosum, indicating abnormal differentiation. *Discontinuity of the skin showing incomplete loss of epidermis.* - This description refers to an **erosion** or **ulceration**, depending on the depth of the epidermal loss. - It does not specifically describe abnormal cellular keratinization. *Keratinization with retained nuclei in the stratum corneum.* - This is the definition of **parakeratosis**, which is a normal finding in mucous membranes but an abnormal finding in skin, often associated with disorders like **psoriasis**. - It indicates incomplete maturation of keratinocytes as they reach the stratum corneum. *Thickening of stratum corneum, often associated with a qualitative abnormality of keratin.* - This describes **hyperkeratosis**, which is an increase in the thickness of the **stratum corneum**. - While it can involve abnormal keratin, it refers to increased thickness, not premature individual cell keratinization.
Question 7: Baby born with membrane around him at the time of birth. Which of the following conditions is depicted?
- A. X-linked ichthyosis (steroid sulfatase deficiency)
- B. Generalized hyperkeratosis (thickened skin)
- C. Ichthyosis vulgaris (dry, scaly skin)
- D. Lamellar ichthyosis (collodion membrane at birth) (Correct Answer)
Explanation: ***Lamellar ichthyosis (collodion membrane at birth)*** - This condition is characterized by a "collodion membrane" at birth, which is a **tight, shiny, parchment-like membrane** that covers the entire body. - The membrane typically **sheds within weeks**, revealing underlying scaling and erythema characteristic of lamellar ichthyosis. *X-linked ichthyosis (steroid sulfatase deficiency)* - Marked by **dark brown, adherent scales**, primarily affecting the neck, trunk, and extensor surfaces. - It usually becomes apparent **several weeks or months after birth** and is not typically associated with a collodion membrane. *Generalized hyperkeratosis (thickened skin)* - This is a general term for **thickening of the outermost layer of the epidermis** and is a feature of many ichthyoses, not a specific condition with a "membrane at birth." - It describes a **symptom** rather than a primary diagnosis presenting with a specific birth membrane. *Ichthyosis vulgaris (dry, scaly skin)* - Presents with **fine, white scaling**, most prominent on the extensor surfaces of the limbs, but it **rarely appears at birth**. - It is typically **mild** and often worsens in dry, cold weather, lacking the characteristic "membrane around him" at birth.
Question 8: Acanthosis nigricans is characterized by all of the following except?
- A. Associated with thick skin with hyperpigmentation
- B. May be a sign of internal malignancy
- C. Common in obese people
- D. Histologically there is hypermelanosis (Correct Answer)
Explanation: ***Histologically there is hypermelanosis*** - This statement is **FALSE** and is the correct answer to this "EXCEPT" question - The characteristic dark appearance of acanthosis nigricans is **NOT due to increased melanin** (hypermelanosis) - Histologically, the key features are **hyperkeratosis, papillomatosis, and mild acanthosis** - There is typically **minimal or no increase in melanocytes or melanin pigment** - The hyperpigmentation seen clinically is an optical effect from the thickened, hyperkeratotic epidermis *May be a sign of internal malignancy* - This statement is **true**; acanthosis nigricans can be a paraneoplastic syndrome associated with internal malignancies - **Malignant acanthosis nigricans** is particularly associated with **gastrointestinal adenocarcinomas** (especially gastric) - This form typically has sudden onset, rapid progression, and more widespread involvement *Common in obese people* - This statement is **true**; acanthosis nigricans is frequently associated with **insulin resistance** - Commonly seen in individuals with **obesity, type 2 diabetes, and metabolic syndrome** - This benign form typically affects flexural areas (neck, axillae, groin) *Associated with thick skin with hyperpigmentation* - This statement is **true**; these are the hallmark clinical features of acanthosis nigricans - Presents as **velvety thickening** and **dark brown to black hyperpigmentation** - Typically affects intertriginous areas and skin folds
Question 9: Which of the following statements is true regarding Acanthosis Nigricans?
- A. May be an indication of skin malignancy
- B. Hypopigmentation
- C. May be associated with Insulin resistant diabetes mellitus (Correct Answer)
- D. Commonly occurs in lean and thin.
Explanation: ***May be associated with Insulin resistant diabetes mellitus*** - **Acanthosis nigricans** is a skin condition characterized by **dark, velvety patches** in body folds like the armpit, neck, and groin. - It is frequently associated with conditions that involve **insulin resistance**, such as type 2 diabetes mellitus and metabolic syndrome, where high insulin levels stimulate epidermal and dermal fibroblast growth. *May be an indication of skin malignancy* - While **malignant acanthosis nigricans** can occur, particularly with internal adenocarcinomas (e.g., gastric cancer), it is **less common** than the benign forms. - The appearance of acanthosis nigricans alone is not directly indicative of skin malignancy; rather, it often signals an underlying systemic issue. *Hypopigmentation* - Acanthosis nigricans is characterized by **hyperpigmentation**, leading to darkened skin patches. - The skin in affected areas appears **darker**, not lighter, than the surrounding skin. *Commonly occurs in lean and thin* - Acanthosis nigricans is more commonly seen in individuals who are **overweight or obese**, as this is strongly correlated with **insulin resistance**. - While it can occur in individuals of normal weight, particularly those with genetic syndromes or endocrine disorders, its prevalence is significantly higher in those with higher BMI.
Question 10: A child is presenting with erythematous follicular papules on the trunk. There are areas of normal skin within the lesions. There is thickening of palms and soles. This child is suffering from -
- A. Seborrheic dermatitis
- B. Psoriasis
- C. Pityriasis rubra pilaris (Correct Answer)
- D. Pityriasis rosea
Explanation: ***Pityriasis rubra pilaris*** - This condition is characterized by **erythematous follicular papules**, often with areas of **normal skin** (islands of sparing or skip areas) amongst the lesions, and can involve **palmoplantar keratoderma** (thickening of palms and soles). - It often presents with a **cephalocaudal spread** and in children, distinct patterns like follicular eruptions on the trunk are common. *Seborrheic dermatitis* - Typically presents as **greasy, yellowish scales** on an erythematous base, commonly affecting areas rich in sebaceous glands like the scalp, face, and chest. - It does not usually present with the **follicular papules** or **palmoplantar thickening described**. *Psoriasis* - Characterized by well-demarcated, **erythematous plaques** with silvery scales, often on extensor surfaces, and can involve pinpoint bleeding (Auspitz sign) when scales are removed. - While it can cause palmoplantar involvement, the presence of **islands of normal skin** within the lesions and follicular papules are more indicative of pityriasis rubra pilaris. *Pityriasis rosea* - Typically begins with a **herald patch**, followed by smaller, oval, fawn-colored or pink lesions with fine scales, often arranged in a "Christmas tree" pattern on the trunk. - It does not present with **follicular papules**, **thickening of palms and soles**, or the characteristic "islands of normal skin" seen in the description.
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