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?
Skin scraping and KOH mounting is primarily used to diagnose which of the following conditions?
Which of the following drugs is effective in the treatment of pityriasis versicolor?
Pathergy test is used for which condition?
What percentage of skin involvement is characteristic of erythroderma?
What is the treatment for granuloma inguinale?
NEET-PG 2013 - Dermatology NEET-PG Practice Questions and MCQs
Question 11: 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 12: 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 13: 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 14: 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 15: 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 16: Skin scraping and KOH mounting is primarily used to diagnose which of the following conditions?
- A. Dermatophyte infection (Correct Answer)
- B. Bacterial infection
- C. Candidiasis
- D. Herpes Simplex Virus (HSV)
Explanation: ***Dermatophyte infection*** - Skin scraping followed by **KOH mounting** is the **primary and gold standard** diagnostic method for dermatophyte infections - **Potassium hydroxide (KOH)** dissolves keratin, making **fungal hyphae and arthroconidia** clearly visible under microscopy - This is the **most common indication** for KOH preparation in dermatology practice - Demonstrates **septate hyphae** characteristic of dermatophytes *Candidiasis* - KOH mounting can also identify *Candida* species by revealing **pseudohyphae and budding yeast cells** - While KOH can diagnose candidiasis, dermatophyte infections remain the **primary and most frequent indication** for this test in skin lesions - Candida more commonly affects mucosal surfaces where other diagnostic methods may be preferred *Bacterial infection* - Bacterial infections are diagnosed using **Gram stain, culture, and sensitivity** testing - KOH mounting is specifically for **fungal elements** and does not visualize bacteria effectively - Bacterial skin infections require different diagnostic approaches *Herpes Simplex Virus (HSV)* - HSV infections are diagnosed using **Tzanck smear** (showing multinucleated giant cells), **viral culture, or PCR** - KOH mounting is exclusively for fungal identification and **cannot detect viruses** - Viral cytopathic effects are not visible with KOH preparation
Question 17: Which of the following drugs is effective in the treatment of pityriasis versicolor?
- A. Ketoconazole (Correct Answer)
- B. Metronidazole
- C. Griseofulvin
- D. Chloroquine
Explanation: ***Ketoconazole*** - **Ketoconazole** is an **azoles antifungal agent** effective against the *Malassezia* species, the causative agent of **pityriasis versicolor**. - It works by inhibiting the synthesis of **ergosterol**, a crucial component of the fungal cell membrane, leading to its disruption and fungal cell death. *Metronidazole* - **Metronidazole** is an **antibiotic** and **amoebicide** primarily used to treat bacterial and parasitic infections. - It has **no antifungal activity** and is thus ineffective against *Malassezia* or other fungal infections. *Griseofulvin* - **Griseofulvin** is an **oral antifungal drug** primarily used for **dermatophyte infections** of the skin, hair, and nails (e.g., tinea capitis, onychomycosis). - It is **ineffective against yeasts and molds**, including *Malassezia*, making it unsuitable for pityriasis versicolor. *Chloroquine* - **Chloroquine** is an **antimalarial drug** also used in the treatment of some autoimmune conditions like lupus erythematosus. - It possesses **no antifungal properties** and is not used to treat fungal infections of any kind.
Question 18: Pathergy test is used for which condition?
- A. Lichen planus
- B. Atopic dermatitis
- C. Behçet's syndrome (Correct Answer)
- D. Reiter's syndrome
Explanation: ***Behçet's syndrome*** - The **pathergy test** is a diagnostic test where a sterile needle is used to prick the skin, and a positive result (erythematous papule or pustule) indicates a hyperreactivity of the skin, common in **Behçet's syndrome**. - This syndrome is a **vasculitis** characterized by recurrent oral and genital ulcers, ocular inflammation, and skin lesions, where pathergy is a characteristic feature. *Lichen planus* - This is an **inflammatory dermatosis** affecting the skin, hair, nails, and mucous membranes, characterized by "6 P's": **Pruritic, Purple, Polygonal, Planar, Papules, and Plaques**. - The pathergy test is **not used** in the diagnosis of lichen planus. *Atopic dermatitis* - Also known as **eczema**, it is a chronic, relapsing inflammatory skin condition characterized by dry, itchy skin and often associated with a personal or family history of allergies, asthma, or allergic rhinitis. - Diagnosis is primarily clinical, focusing on characteristic skin lesions and symptoms, and the **pathergy test is not applicable**. *Reiter's syndrome* - Now known as **reactive arthritis**, this condition is an autoimmune disorder that develops in response to an infection elsewhere in the body, typically genitourinary or gastrointestinal. - It classically presents with **arthritis, urethritis, and conjunctivitis** (Can't see, can't pee, can't climb a tree), and the **pathergy test is not used** for its diagnosis.
Question 19: What percentage of skin involvement is characteristic of erythroderma?
- A. More than 90% (Correct Answer)
- B. Less than 30%
- C. 30% to 60%
- D. 60% to 70%
Explanation: ***More than 90%*** - Erythroderma, also known as **exfoliative dermatitis**, is defined by diffuse redness and scaling involving **more than 90% of the body surface area**. - This extensive involvement leads to significant physiological disturbances due to impaired skin barrier function. *Less than 30%* - Skin involvement less than 30% does not meet the criteria for erythroderma and would be considered more localized dermatological conditions. - This percentage of involvement would typically indicate a benign rash or localized eczema, not a widespread inflammatory process. *30% to 60%* - While significant, 30% to 60% skin involvement is still insufficient to classify a condition as erythroderma. - This range might be seen in severe but still localized forms of conditions like psoriasis or eczema. *60% to 70%* - 60% to 70% involvement is extensive but falls short of the critical threshold for erythroderma. - Although indicating widespread disease, it does not constitute the near-total body erythema and scaling characteristic of erythroderma.
Question 20: What is the treatment for granuloma inguinale?
- A. Tetracycline
- B. Azithromycin (Correct Answer)
- C. Clarithromycin
- D. Streptomycin
Explanation: ***Azithromycin*** - **Azithromycin** is the recommended first-line treatment for **granuloma inguinale** (donovanosis) caused by *Klebsiella granulomatis*. - Current recommended regimens: **Azithromycin 1g orally once weekly** OR **500mg daily for at least 3 weeks** (until all lesions have completely healed). - Preferred due to excellent tissue penetration, good efficacy, and convenient dosing that improves patient compliance. *Tetracycline* - **Tetracycline** (500mg four times daily) was historically used but has been largely replaced by **doxycycline** (100mg twice daily) as the preferred tetracycline-class antibiotic. - While effective against *Klebsiella granulomatis*, it requires frequent dosing leading to poor adherence. - **Doxycycline** (not listed here) is actually considered a co-first-line option alongside azithromycin in current CDC guidelines. *Clarithromycin* - **Clarithromycin** is a macrolide antibiotic but is not a recommended first-line agent for granuloma inguinale. - Limited clinical data supports its use for this condition, and it is not included in standard treatment guidelines. - Azithromycin from the same macrolide class is preferred due to better-established efficacy. *Streptomycin* - **Streptomycin** is an aminoglycoside antibiotic primarily used for mycobacterial infections (e.g., tuberculosis, plague). - Not indicated for granuloma inguinale as *Klebsiella granulomatis* responds well to macrolides (azithromycin) and tetracyclines (doxycycline). - Requires parenteral administration and has significant toxicity concerns (ototoxicity, nephrotoxicity).