Most common metal in contact allergic dermatitis is?
The Grattage test is used to diagnose which of the following conditions?
What is the treatment of choice for lichen planus?
Nikolsky's sign is associated with which of the following conditions?
Acantholysis is not seen in:
What is the most common trigger associated with erythema multiforme?
Treatment of dermatitis herpetiformis:
In which condition is an ulceronecrotic nodule typically observed?
Schamberg's purpura is seen on?
Which type of ultraviolet radiation causes the most skin disorders?
NEET-PG 2013 - Dermatology NEET-PG Practice Questions and MCQs
Question 11: Most common metal in contact allergic dermatitis is?
- A. Gold
- B. Silver
- C. Aluminum
- D. Nickel (Correct Answer)
Explanation: ***Nickel*** - **Nickel** is the most frequent cause of **metal-induced contact allergic dermatitis**, affecting a significant portion of the population. - It is commonly found in jewelry, belt buckles, buttons, and other everyday metallic objects. *Gold* - **Gold allergy** can occur but is much less common than nickel allergy. - Reactions typically arise from jewelry and may involve **allergic contact dermatitis**. *Silver* - **Silver allergy** is quite rare and often due to impurities or alloys rather than pure silver itself. - Pure silver is generally considered **hypoallergenic**. *Aluminum* - **Aluminum** is generally not a common cause of **allergic contact dermatitis**. - While it can be an irritant in some products (e.g., antiperspirants), true allergic reactions are infrequent.
Question 12: The Grattage test is used to diagnose which of the following conditions?
- A. Tinea capitis
- B. Lichen planus
- C. Pemphigus vulgaris
- D. Psoriasis (Correct Answer)
Explanation: ***Psoriasis*** - The **Grattage test** (candle grease sign) involves **scraping the psoriatic lesion** to reveal characteristic features - First reveals **fine, silvery-white scales** resembling candle wax - Further scraping exposes **pinpoint bleeding points** (**Auspitz sign**) due to exposure of dilated capillaries in dermal papillae - This combination is **pathognomonic for psoriasis** and helps differentiate it from other scaly dermatoses *Tinea capitis* - A **fungal infection of the scalp** caused by dermatophytes - Diagnosed by **KOH mount** (showing fungal hyphae), **fungal culture**, and sometimes **Wood's lamp examination** - The Grattage test is not used for diagnosing fungal infections *Lichen planus* - Characterized by **purplish, polygonal, flat-topped, pruritic papules and plaques** - Surface shows **Wickham's striae** (fine white lines) - Diagnosis is **clinical**, supported by **skin biopsy** showing band-like lymphocytic infiltrate and sawtooth rete ridges - The Grattage test is not applicable *Pemphigus vulgaris* - A severe **autoimmune blistering disorder** with **suprabasal acantholysis** - Presents with **flaccid bullae** that rupture easily, leaving erosions - Diagnosed by **skin biopsy**, **direct immunofluorescence** (intercellular IgG and C3 deposits), and **Nikolsky's sign** (positive) - The Grattage test is not used for bullous disorders
Question 13: What is the treatment of choice for lichen planus?
- A. Topical corticosteroids (Correct Answer)
- B. Systemic corticosteroids
- C. Antihistamines
- D. Acitretin
Explanation: ***Topical corticosteroids*** - **Topical corticosteroids** are the first-line treatment for localized lichen planus due to their potent **anti-inflammatory** and **immunosuppressive** effects. - They effectively reduce **itching**, **inflammation**, and the characteristic **violaceous papules** of lichen planus. *Systemic corticosteroids* - **Systemic corticosteroids** are typically reserved for widespread, severe, or refractory cases of lichen planus, not as initial treatment. - Their use is limited by potential **systemic side effects**, such as **osteoporosis**, **hypertension**, and **diabetes**. *Antihistamines* - **Antihistamines** primarily target **itching** (pruritus) associated with lichen planus but do not address the underlying **inflammatory process** or resolve the skin lesions themselves. - They may be used as an adjunct for symptomatic relief, especially for nocturnal pruritus. *Acitretin* - **Acitretin** is a **retinoid** used for severe or refractory cases of lichen planus (including erosive, oral, and hypertrophic variants), but not as first-line treatment for localized cutaneous disease. - It carries significant **teratogenic risks** and other side effects, making it unsuitable as initial therapy when topical corticosteroids are effective.
Question 14: Nikolsky's sign is associated with which of the following conditions?
- A. Herpes zoster
- B. Bullous impetigo
- C. All of the options
- D. Pemphigus (Correct Answer)
Explanation: ***Pemphigus*** - **Nikolsky's sign** is the **most characteristic and consistent** clinical finding in pemphigus, where slight lateral pressure on seemingly normal skin near a blister or erosion causes the epidermis to shear off, forming a new blister or denudation. - This sign indicates **intraepidermal blistering** due to the loss of cell adhesion (acantholysis) caused by autoantibodies against desmoglein proteins. - **Pemphigus is the classic condition** associated with a positive Nikolsky's sign in medical literature and examinations. *Herpes zoster* - **Herpes zoster** (shingles) is characterized by painful, vesicular eruptions in a **dermatomal distribution**, which do **not exhibit Nikolsky's sign**. - The vesicles in herpes zoster are **intraepidermal** but result from viral cytopathic effect, not acantholysis, and the roof of the vesicle remains intact with lateral pressure. *Bullous impetigo* - Bullous impetigo is a superficial skin infection caused by *Staphylococcus aureus* that produces **large, flaccid blisters**. - While **Nikolsky's sign can occasionally be positive** in bullous impetigo (particularly in staphylococcal scalded skin syndrome), it is **much less consistent and prominent** compared to pemphigus. - The key distinction is that pemphigus remains the **most characteristic association** with Nikolsky's sign in clinical practice and examinations. *All of the options* - This option is incorrect because Nikolsky's sign is **most specifically and consistently associated with pemphigus**. - While bullous impetigo may occasionally show Nikolsky's sign, **pemphigus is the classic answer** for this clinical finding in medical examinations.
Question 15: Acantholysis is not seen in:
- A. Lichen planus (Correct Answer)
- B. Dermatitis herpetiformis
- C. Hailey-Hailey disease
- D. Bullous pemphigoid
Explanation: ***Lichen planus*** - **Lichen planus** is a **non-blistering inflammatory dermatosis** where **acantholysis is completely absent** as it is not a blistering disorder. - Characterized by **acanthosis** (epidermal thickening), **hyperkeratosis**, **wedge-shaped hypergranulosis**, and a **band-like lymphocytic infiltrate** at the dermo-epidermal junction. - The pathology involves **basal cell liquefaction** and inflammation, not loss of keratinocyte cohesion. - **Most appropriate answer** as lichen planus is fundamentally a non-blistering condition, unlike the other options which are blistering diseases. *Bullous pemphigoid* - A **subepidermal bullous disease** where blister formation occurs *below* the epidermis at the **dermo-epidermal junction**. - Autoantibodies target **BP180 and BP230** antigens in **hemidesmosomes**, causing separation between epidermis and dermis. - **No acantholysis** is present as keratinocytes within the epidermis remain cohesive; the split is subepidermal. - Also a correct answer, but less optimal than lichen planus as it is still a blistering disease. *Dermatitis herpetiformis* - A **subepidermal blistering disease** associated with **celiac disease** and characterized by intensely pruritic papulovesicles. - Features **neutrophilic microabscesses** in dermal papillae and granular **IgA deposits** at the dermo-epidermal junction. - **No acantholysis** as blister formation is subepidermal due to immune complex deposition, not loss of keratinocyte adhesion. - Also technically correct, but lichen planus remains the best answer. *Hailey-Hailey disease* - **INCORRECT:** This condition is characterized by **suprabasal acantholysis**, making it a classic example where acantholysis IS present. - Also known as **familial benign chronic pemphigus**, caused by mutation in **ATP2C1 gene** affecting calcium regulation. - Leads to chronic, relapsing blistering and erosions in **intertriginous areas** (axillae, groin). - **Acantholysis is the defining histological feature**, producing a "dilapidated brick wall" appearance.
Question 16: What is the most common trigger associated with erythema multiforme?
- A. Herpes simplex (Correct Answer)
- B. Mycoplasma pneumoniae
- C. TB
- D. Drugs
Explanation: ***Herpes simplex*** - **Herpes simplex virus (HSV)** is the most common precipitating factor for **erythema multiforme**, accounting for **50-60% of identifiable cases**, particularly the recurrent form. - The rash typically appears **10-14 days after an HSV outbreak**, suggesting an immune-mediated reaction. - **HSV-1** is more commonly implicated than HSV-2. *Mycoplasma pneumoniae* - **Mycoplasma pneumoniae** is the **second most common infectious trigger** for erythema multiforme, especially in children and young adults. - EM associated with Mycoplasma typically occurs during or after respiratory infection. - However, it is still less common than HSV as a trigger. *TB* - **Tuberculosis (TB)** is not typically associated with erythema multiforme. - While other infections can trigger erythema multiforme, TB is rarely implicated. *Drugs* - **Drug reactions** are a recognized cause of erythema multiforme, but they are less common than HSV infection as a trigger. - Certain medications like **sulfonamides, anticonvulsants, NSAIDs, and penicillins** are among the drugs that can induce erythema multiforme.
Question 17: Treatment of dermatitis herpetiformis:
- A. Dapsone
- B. Sulfonamide
- C. Gluten-free diet
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Dermatitis herpetiformis (DH)** is a chronic, intensely itchy blistering skin condition associated with **celiac disease**. - Effective management involves both a **gluten-free diet** to address the underlying autoimmune process and medications like **dapsone** or **sulfonamides** for symptomatic relief. *Gluten-free diet* - A strict **gluten-free diet** is crucial for long-term management as it addresses the underlying small intestinal enteropathy associated with **celiac disease** and **dermatitis herpetiformis**. - While it may take several months to see full skin improvement, it can eventually lead to resolution of skin lesions and reduced or eliminated need for medication. *Dapsone* - **Dapsone** is a rapidly effective medication for alleviating the intense itching and rash of **dermatitis herpetiformis**, often providing relief within 24-48 hours. - It works by inhibiting neutrophil migration and inflammation, but does not treat the underlying gluten-sensitive enteropathy. *Sulfonamide* - **Sulfonamides**, such as sulfapyridine or sulfamethoxypyridazine, can be used as an alternative for patients who cannot tolerate **dapsone** or who respond inadequately to it. - Like dapsone, these medications provide symptomatic relief by reducing inflammation and neutrophil activity in the skin, but do not address the gluten-induced intestinal damage.
Question 18: In which condition is an ulceronecrotic nodule typically observed?
- A. Lucio's leprosy (Correct Answer)
- B. Lepromatous leprosy
- C. Indeterminate leprosy
- D. Histoid leprosy
Explanation: ***Lucio's leprosy*** - This is a rare, diffuse variant of **lepromatous leprosy** characterized by widespread, diffuse infiltration of the skin without distinct nodules. - The distinctive feature is the occurrence of **necrotizing vasculitis**, leading to painful, irregular ulcers and scars, known as **Lucio phenomenon** or erythema necroticans. *Lepromatous leprosy* - Characterized by **multiple, symmetrical nodules**, plaques, and diffuse infiltration, but typically without the profound ulceronecrotic changes seen in Lucio's leprosy. - The immune response is weak, leading to high bacterial load and widespread involvement, but usually not spontaneous ulceration. *Indeterminate leprosy* - This is an **early, undifferentiated form** of leprosy, characterized by a single or a few hypopigmented or erythematous macules. - Distinct nodules or ulceronecrotic lesions are not a feature of indeterminate leprosy, as the disease has not yet progressed to develop specific clinical manifestations. *Histoid leprosy* - A rare variant of lepromatous leprosy that presents with **cutaneous nodules** and papules that often resemble dermatofibromas or xanthomas. - These nodules are firm, smooth, and have a unique histological appearance, but they do not typically undergo spontaneous ulceronecrotic changes like those in Lucio's leprosy.
Question 19: Schamberg's purpura is seen on?
- A. Face
- B. Feet (Correct Answer)
- C. Chest
- D. Arms
Explanation: ***Feet*** - Schamberg's purpura, also known as **progressive pigmented purpuric dermatosis**, most commonly affects the **lower extremities**, particularly the feet and ankles. - The characteristic reddish-brown patches with "cayenne pepper" spots are due to **capillary inflammation** and extravasation of red blood cells. *Face* - While purpura can occur on the face due to other conditions, Schamberg's purpura **rarely presents in this location**. - Facial lesions often suggest different underlying etiologies, such as **vasculitis** or trauma. *Chest* - The chest is an **uncommon site** for Schamberg's purpura. - Involvement of the trunk is less typical compared to the dependent areas of the legs. *Arms* - Although the arms can occasionally be affected, the **feet and lower legs are the predominant sites** for Schamberg's purpura due to factors like **gravity** and hydrostatic pressure. - When present on the arms, it might indicate a more widespread or atypical presentation.
Question 20: Which type of ultraviolet radiation causes the most skin disorders?
- A. UV-A
- B. UV-B (Correct Answer)
- C. UV-C
- D. None of the options
Explanation: ***UV-B*** - **UV-B radiation** is a major cause of **sunburn** and directly damages DNA, leading to most **skin cancers** (basal cell carcinoma, squamous cell carcinoma, and melanoma). - It plays a significant role in photoaging and the development of most **skin disorders** related to sun exposure. *UV-A* - **UV-A radiation** penetrates deeper into the skin than UV-B and is primarily associated with **photoaging**, producing wrinkles and fine lines. - While it contributes to skin cancer development, its direct role in DNA damage and sunburn is less than that of UV-B. *UV-C* - **UV-C radiation** is the most damaging type of UV light, but it is almost entirely **absorbed by the Earth's ozone layer** and does not reach the Earth's surface. - Therefore, it does not typically cause skin disorders in humans under natural conditions. *None of the options* - This option is incorrect because **UV-B radiation** is well-established as a primary cause of numerous skin disorders, including most skin cancers and sunburn.