Which of the following statements about Bowen's disease is correct?
Which of the following statements is true regarding pemphigus vulgaris?
In which of the following conditions is phototherapy, specifically ultraviolet light therapy, useful for treatment?
Acanthosis nigricans is characterized by all of the following except?
Which of the following organisms has a role to play in Seborrheic dermatitis?
Pruritus is a feature of which of the following conditions?
A girl about to marry has comedonal acne. Drug to treat such a case is:
Maculae cerulea is seen in ?
Which of the following is true about keratinocytes?
NEET-PG 2015 - Dermatology NEET-PG Practice Questions and MCQs
Question 11: Which of the following statements about Bowen's disease is correct?
- A. Chronic sun exposure is a known risk factor.
- B. It is more common in fair-skinned individuals.
- C. There is a link between HSV infection and Bowen's disease.
- D. It is a form of squamous cell carcinoma in situ. (Correct Answer)
Explanation: ***It is a form of squamous cell carcinoma in situ.*** - **Bowen's disease** is, by definition, **squamous cell carcinoma in situ (SCC in situ)**. - It is characterized by full-thickness epidermal atypia of keratinocytes **without invasion through the basement membrane**. - This statement is **definitional** and represents the fundamental nature of what Bowen's disease is, making it the **best answer** among the options. *Chronic sun exposure is a known risk factor.* - This statement is **medically accurate**. Chronic UV exposure is indeed a well-established risk factor for Bowen's disease. - However, this describes a **risk factor** rather than defining what the condition is. - Other risk factors include **arsenic exposure**, **ionizing radiation**, **immunosuppression**, and **HPV infection** (particularly in anogenital sites). - While true, this is not as fundamental as the definitional statement. *It is more common in fair-skinned individuals.* - This statement is also **medically accurate**. Bowen's disease occurs more frequently in fair-skinned individuals (Fitzpatrick skin types I-II). - Fair skin provides less melanin protection against UV damage, increasing susceptibility to various forms of skin cancer including Bowen's disease. - However, this describes **epidemiology** rather than defining the condition itself. *There is a link between HSV infection and Bowen's disease.* - This statement is **incorrect**. There is **no established association** between Herpes Simplex Virus (HSV) and Bowen's disease. - **Human Papillomavirus (HPV)**, particularly high-risk types 16 and 18, is associated with Bowen's disease, especially in anogenital locations. - This represents a common confusion between HSV and HPV.
Question 12: Which of the following statements is true regarding pemphigus vulgaris?
- A. It primarily affects the dermal-epidermal junction.
- B. It is a subepidermal blistering disease.
- C. It is an intraepidermal blistering disease. (Correct Answer)
- D. Antibodies are formed against basement membrane proteins.
Explanation: ***It is an intraepidermal blistering disease.*** - **Pemphigus vulgaris** is characterized by the formation of blisters *within the epidermis* due to the loss of cell-to-cell adhesion between **keratinocytes**. - This **acantholysis** results from autoantibodies targeting **desmosomes**, specifically **desmoglein 1 and 3**. *It is a subepidermal blistering disease.* - This statement is incorrect as it describes conditions like **bullous pemphigoid** or **dermatitis herpetiformis**, where blisters form *below* the epidermis. - In pemphigus vulgaris, the separation occurs *above* the basement membrane within the epidermal layer. *It primarily affects the dermal-epidermal junction.* - This is characteristic of **bullous pemphigoid** or **epidermolysis bullosa acquisita**, where the primary pathology involves the separation at the interface between the dermis and epidermis. - Pemphigus vulgaris directly affects the adhesion *within* the epidermis itself. *Antibodies are formed against basement membrane proteins.* - This is characteristic of **bullous pemphigoid**, where autoantibodies target components of the **basement membrane zone**, such as **BP180** and **BP230**. - In pemphigus vulgaris, the autoantibodies target **desmogleins** on the surface of keratinocytes, not basement membrane proteins.
Question 13: In which of the following conditions is phototherapy, specifically ultraviolet light therapy, useful for treatment?
- A. Psoriasis (Correct Answer)
- B. Tinea corporis
- C. Pemphigus
- D. PMLE
Explanation: ***Psoriasis*** - **Phototherapy** (narrowband UVB, broadband UVB, or PUVA) is a **well-established first-line treatment** for **moderate-to-severe psoriasis**. - It works by **suppressing overactive immune cells** in the skin, reducing inflammation and decreasing keratinocyte proliferation. - **Direct therapeutic effect** on active psoriatic lesions makes this the primary indication for phototherapy in dermatology. *Tinea corporis* - **Tinea corporis** is a **superficial fungal infection** (dermatophytosis) of the skin. - Requires **antifungal medications** (topical azoles or oral terbinafine/griseofulvin) for treatment. - **Phototherapy has no antifungal activity** and is not used for this condition. *Pemphigus* - **Pemphigus** is an **autoimmune blistering disease** with intraepidermal acantholysis. - Treatment requires **systemic immunosuppression** (corticosteroids, rituximab, azathioprine). - **Phototherapy is not indicated** and could potentially worsen the condition. *PMLE* - **Polymorphous light eruption (PMLE)** is a common **photosensitivity disorder**. - While **prophylactic photohardening** (gradual controlled UV exposure) can be used to build tolerance **before sun exposure season**, this is a **preventative desensitization strategy**, not treatment of active disease. - Unlike psoriasis, phototherapy does **not treat active PMLE lesions** and can trigger flares if not done properly. - The primary approach for active PMLE is **sun avoidance, sun protection, and topical corticosteroids**.
Question 14: 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 15: Which of the following organisms has a role to play in Seborrheic dermatitis?
- A. Pityrosporum ovale (Correct Answer)
- B. Propionibacterium
- C. Candida albicans
- D. None of the above
Explanation: ***Pityrosporum ovale*** - **Pityrosporum ovale**, now known as **Malassezia furfur**, is a lipophilic yeast that colonizes the skin and plays a significant role in the pathogenesis of **seborrheic dermatitis**. - Its presence is commonly associated with the inflammatory response seen in seborrheic dermatitis, though the exact mechanism is not fully understood. *Candida albicans* - **Candida albicans** is a common cause of **mucocutaneous candidiasis** and **intertrigo**, but it is not directly implicated in the etiology of seborrheic dermatitis. - While it can cause skin infections, its typical presentation involves erythematous, macerated rashes with satellite lesions in skin folds. *Propionibacterium* - **Propionibacterium acnes**, now known as **Cutibacterium acnes**, is primarily associated with the pathogenesis of **acne vulgaris**. - It plays a role in the inflammation and comedone formation characteristic of acne, not the scaling and erythema of seborrheic dermatitis. *None of the above* - This option is incorrect because **Pityrosporum ovale (Malassezia furfur)** is a well-recognized organism involved in seborrheic dermatitis. - The other organisms listed are associated with different dermatological conditions.
Question 16: Pruritus is a feature of which of the following conditions?
- A. Pemphigus foliaceous
- B. Pemphigus vulgaris
- C. Bullous pemphigoid (Correct Answer)
- D. None of the options
Explanation: ***Bullous pemphigoid*** - **Pruritus**, often severe, is a common and early symptom of bullous pemphigoid, often preceding the appearance of skin lesions. - The disease involves autoantibodies against **hemidesmosomal proteins** (BPAG1, BPAG2), leading to subepidermal blister formation. *Pemphigus foliaceous* - This condition is characterized by **superficial blistering** and erosions, but **pruritus is typically mild or absent**. - Blisters form in the **granular layer of the epidermis** due to autoantibodies against desmoglein 1. *Pemphigus vulgaris* - Patients with pemphigus vulgaris present with **flaccid blisters and erosions**, mainly affecting the skin and mucous membranes, but **pruritus is not a prominent feature**. - The disease involves intraepidermal blistering caused by autoantibodies targeting **desmoglein 3 (and sometimes desmoglein 1)**. *None of the options* - This option is incorrect, as **pruritus is a characteristic symptom of bullous pemphigoid**.
Question 17: A girl about to marry has comedonal acne. Drug to treat such a case is:
- A. Topical antibiotic
- B. Retinoids (Correct Answer)
- C. Estrogen
- D. Benzoyl peroxide
Explanation: ***Retinoids*** - **Topical retinoids** (e.g., tretinoin, adapalene) are the gold standard for comedonal acne as they normalize **follicular keratinization** and prevent microcomedone formation. - Being **Category C in pregnancy**, topical retinoids require **contraception counseling** for women of childbearing age but are still first-line treatment with proper precautions. *Benzoyl peroxide* - **Benzoyl peroxide** has mild comedolytic properties but is primarily effective for **inflammatory acne** due to its antimicrobial action against *Cutibacterium acnes*. - Less effective than retinoids for purely **comedonal acne** as it doesn't address the core pathology of abnormal keratinization. *Estrogen* - **Hormonal therapy** with estrogen-containing contraceptives reduces sebum production by suppressing androgens but takes **3-6 months** to show effects. - More suitable for **hormonal acne** with inflammatory lesions rather than purely comedonal acne, and not first-line for this presentation. *Topical antibiotic* - **Topical antibiotics** (clindamycin, erythromycin) target bacterial overgrowth and inflammation but have limited efficacy in **non-inflammatory comedonal acne**. - Risk of **bacterial resistance** when used alone, and they don't address the underlying hyperkeratinization that causes comedone formation.
Question 18: Maculae cerulea is seen in ?
- A. Pediculosis hominis corporis
- B. Scabies
- C. Pediculosis capitis
- D. Pediculosis pubis (Correct Answer)
Explanation: ***Pediculosis pubis*** - **Maculae ceruleae** (blue spots) are **pathognomonic** for pubic louse (*Pthirus pubis*) infestation. - These characteristic **bluish-gray macules** are typically found on the trunk, thighs, and lower abdomen. - They result from the **anticoagulant in louse saliva** converting hemoglobin to biliverdin at feeding sites, causing localized hemorrhage and pigment deposition. - This is a **classic diagnostic feature** of pediculosis pubis. *Pediculosis hominis corporis* - Body louse infestation causes **pruritus** and **excoriations**, typically along clothing lines (waistband, collar). - **Maculae ceruleae** are not a feature of body louse infestation. *Pediculosis capitis* - Head lice infestation presents with **scalp pruritus**, **nits on hair shafts**, and excoriations. - **Maculae ceruleae** do not occur with head lice. *Scabies* - Caused by *Sarcoptes scabiei* mite burrowing in the stratum corneum. - Presents with **burrows**, **papules**, **vesicles**, and intense **nocturnal pruritus**. - **Maculae ceruleae** are NOT associated with scabies infestation.
Question 19: Which of the following is true about keratinocytes?
- A. Differentiate in basal layer
- B. Ectoderm derived cell (Correct Answer)
- C. Mature in basal layer
- D. Present only in basal layer
Explanation: ***Ectoderm derived cell*** - Keratinocytes originate from the **ectoderm**, one of the three primary germ layers in embryonic development, which gives rise to the epidermis. - This ectodermal origin is fundamental to their role in forming the protective outer layer of the skin. *Differentiate in basal layer* - Keratinocytes in the **basal layer (stratum basale)** are primarily responsible for **proliferation** (cell division) rather than differentiation. - **Differentiation** into flattened, keratin-filled cells occurs as they migrate upwards through the epidermal layers. *Mature in basal layer* - Maturation, which involves the accumulation of **keratin** and the loss of organelles, primarily occurs in the **upper layers** of the epidermis (stratum spinosum, granulosum, corneum). - The basal layer is where new cells are generated, not where they reach their mature, fully keratinized state. *Present only in basal layer* - While keratinocytes originate in the basal layer, they are the **predominant cell type throughout all layers of the epidermis**. - They represent approximately 90% of epidermal cells and are found from the stratum basale to the stratum corneum.