Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 311: All of the following are not true with respect to erythema multiforme except?

A. Most commonly due to leukemia
B. Steroids are the drug of choice
C. Koebner's phenomenon is seen
D. Targetoid lesions are seen (Correct Answer)

Explanation: ***Targetoid lesions are seen*** - **Erythema multiforme (EM)** is characterized by distinctive **targetoid lesions** (target lesions) with three concentric zones: a dusky center, a pale middle ring, and an erythematous outer ring. - These lesions are a hallmark of EM and differentiate it from many other dermatological conditions. *Most commonly due to leukemia* - **Erythema multiforme** is most commonly associated with **infections**, particularly **herpes simplex virus (HSV)**, rather than leukemia. - Other common triggers include **mycoplasma infections** and certain **medications**. *Steroids are the drug of choice* - For typical, mild **erythema multiforme**, **topical steroids** may be used for symptomatic relief, but they are generally **not the drug of choice** for severe or widespread disease. - **Systemic steroids** are controversial and not routinely recommended for uncomplicated EM, as they may prolong the course or lead to recurrences, though they might be considered in severe cases or to prevent progression to Stevens-Johnson syndrome. *Koebner's phenomenon is seen* - The **Koebner phenomenon** (isomorphic response), where new lesions appear at sites of trauma, is classically associated with conditions like **psoriasis**, **lichen planus**, and **vitiligo**. - It is **not typically seen** in erythema multiforme.

Question 312: 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 313: Dermatological manifestation of which of the following diseases?

A. Photo dermatitis
B. Pellagra (Correct Answer)
C. Acrodermatitis enteropathica
D. Vitamin B deficiency

Explanation: ***Pellagra*** - The image shows a classic "butterfly" rash on the face, specifically a photosensitive dermatitis, which is a hallmark of **pellagra**. - Pellagra is caused by a deficiency of **niacin (vitamin B3)**, characterized by the "3 D's": **dermatitis**, **diarrhea**, and **dementia**. *Photo dermatitis* - While pellagra often presents with photosensitive dermatitis, "photo dermatitis" is a general term for **skin inflammation caused by light exposure** and not a specific disease itself. - It could be caused by various factors, including medication, immune reactions, or other underlying conditions, but the pattern seen here is highly suggestive of pellagra. *Acrodermatitis enteropathica* - This condition is a **hereditary zinc deficiency** that typically presents with a periorificial and acral dermatitis. - The skin lesions are typically **vesicular-pustular or eczematous** and do not usually have the distinct butterfly pattern of photosensitive dermatitis seen in the image. *Vitamin B deficiency* - While pellagra is a vitamin B **(niacin, B3)** deficiency, this option is too broad. - Other vitamin B deficiencies, such as **riboflavin (B2)** or **pyridoxine (B6)** deficiency, have different dermatological manifestations like angular cheilitis, glossitis, or seborrheic dermatitis, but not the characteristic facial rash seen here.

Question 314: Which is TRUE about dermatologic emergencies?

A. Pyoderma gangrenosum needs urgent debridement
B. DRESS syndrome needs immediate drug cessation (Correct Answer)
C. TEN requires immediate systemic steroids
D. Calciphylaxis treatment focuses on wound care

Explanation: **DRESS syndrome needs immediate drug cessation** - **Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)** is a severe hypersensitivity reaction requiring immediate identification and withdrawal of the causative drug to prevent multi-organ failure. - Continuation of the offending drug can lead to worsening symptoms and potentially fatal outcomes due to progressive organ damage. *Pyoderma gangrenosum needs urgent debridement* - **Pyoderma gangrenosum (PG)** is a **neutrophilic dermatosis** characterized by painful, rapidly enlarging ulcers. - **Debridement** of PG lesions is generally **contraindicated** as it can worsen the ulceration through **pathergy**, a phenomenon where minor trauma induces new lesions. *TEN requires immediate systemic steroids* - **Toxic Epidermal Necrolysis (TEN)** is a life-threatening skin reaction characterized by widespread epidermal detachment. - While controversy exists, **systemic corticosteroids** are generally **not recommended** in TEN due to potential for increased infection risk and delayed re-epithelialization without clear evidence of benefit. *Calciphylaxis treatment focuses on wound care* - While **wound care** is a crucial component of **calciphylaxis** management, it is not the sole focus. - **Calciphylaxis** treatment also includes aggressive measures to reduce **calcium-phosphate product**, manage pain, and address underlying conditions such as **end-stage renal disease**.

Question 315: A 35-year-old female presents with recurrent painful nodules on shins, associated with fever and arthralgia. Previous biopsy showed septal panniculitis. She's now pregnant at 20 weeks. Most appropriate treatment is:

A. Colchicine
B. Prednisone (Correct Answer)
C. Potassium iodide
D. Indomethacin

Explanation: ***Prednisone*** - This patient likely has **erythema nodosum** (EN) given the recurrent painful nodules on shins, fever, and arthralgia, along with septal panniculitis on biopsy. **Prednisone (corticosteroids)** are appropriate for moderate to severe cases of EN, especially when associated with systemic symptoms like fever and arthralgia, and are considered safe during the second trimester of pregnancy. - While mild cases can be managed with supportive care, the presence of recurrent and systemic symptoms warrants a more active treatment, and prednisone effectively reduces **inflammation and pain**. *Colchicine* - Colchicine is sometimes used for EN, particularly in chronic or recurrent cases that are refractory to NSAIDs. However, evidence for its use in EN is not as strong as for corticosteroids, and **systemic corticosteroids** are generally preferred for significant systemic symptoms. - Data on **colchicine use in pregnancy** is limited; some studies suggest an increased risk of aneuploidy or congenital malformations, making it a less preferred option compared to prednisone during pregnancy, especially with alternatives available. *Potassium iodide* - **Potassium iodide** has been used as a treatment for EN, particularly for chronic or recurrent forms, acting by modifying the inflammatory response. Its exact mechanism is not fully understood. - However, **potassium iodide is contraindicated in pregnancy** due to the risk of fetal goiter and hypothyroidism, making it an inappropriate choice for a pregnant patient. *Indomethacin* - **Indomethacin** is a non-steroidal anti-inflammatory drug (NSAID) and can be effective for pain and inflammation associated with EN. It would be a consideration for mild to moderate cases. - **NSAIDs are generally avoided in the third trimester of pregnancy** due to risks of premature closure of the ductus arteriosus and oligohydramnios. While potentially used in the second trimester with caution, for a moderate to severe presentation with systemic symptoms in pregnancy, **corticosteroids are generally preferred** over NSAIDs due to their stronger anti-inflammatory effect and better safety profile in the second trimester for this indication.

Question 316: Which finding is characteristic of erythema multiforme?

A. Linear IgA deposits
B. Target lesions (Correct Answer)
C. Nikolsky sign
D. Butterfly rash

Explanation: ***Target lesions*** - **Target lesions**, characterized by concentric rings of erythema and edema, are the **hallmark clinical feature** of erythema multiforme. - These lesions typically have a **central blister or dark area**, surrounded by a pale ring of edema, and an outermost erythematous halo. *Linear IgA deposits* - **Linear IgA deposits** at the dermoepidermal junction are characteristic of **linear IgA bullous dermatosis**, *not* erythema multiforme. - This condition is an **autoimmune blistering disease** distinct from erythema multiforme. *Nikolsky sign* - The **Nikolsky sign**, which is the dislodgment of intact superficial epidermis by lateral pressure, is characteristic of **pemphigus vulgaris** and **toxic epidermal necrolysis**, *not* erythema multiforme. - It indicates **intraepidermal or subepidermal blistering** due to weak cell-to-cell adhesion. *Butterfly rash* - A **butterfly rash**, or malar rash, is characteristic of **systemic lupus erythematosus (SLE)**, *not* erythema multiforme. - This rash typically appears across the **cheeks and bridge of the nose** and is often exacerbated by sun exposure.

Question 317: Patient on anti-TB drugs develops tender nodules on shins. Most likely diagnosis is:

A. Sweet syndrome
B. Panniculitis
C. Erythema multiforme
D. Erythema nodosum (Correct Answer)

Explanation: ***Erythema nodosum*** - Erythema nodosum is a common **cutaneous adverse drug reaction** to anti-TB medications, presenting with **tender, erythematous nodules** typically on the shins. - It is a form of **panniculitis** (inflammation of subcutaneous fat) specifically associated with various triggers, including infections and drugs, making it highly probable in this context. *Sweet syndrome* - Sweet syndrome (acute febrile neutrophilic dermatosis) presents with **tender, erythematous plaques and nodules** often associated with fever and leukocytosis. - While it can be drug-induced, it typically involves a more widespread skin eruption and prominent systemic symptoms like **fever**, which are not specified here. *Panniculitis* - Panniculitis is a general term for **inflammation of the subcutaneous fat**, and erythema nodosum is a type of panniculitis. - This option is too broad; while accurate, "Erythema nodosum" is the **most specific and likely diagnosis** given the patient’s presentation in the context of anti-TB drug use. *Erythema multiforme* - Erythema multiforme is characterized by **target lesions** (concentric rings of erythema and edema) and often involves mucous membranes. - The description of **tender nodules on shins** does not fit the characteristic morphology of erythema multiforme.

Question 318: All are true about lichen planus EXCEPT:

A. Spares oral mucosa (Correct Answer)
B. Wickham's striae present
C. Violaceous flat papules
D. Koebner phenomenon positive

Explanation: ***Spares oral mucosa*** - This statement is incorrect because **lichen planus frequently involves the oral mucosa**, presenting as white reticular lesions, erosions, or plaques. - Oral involvement is common and can be the only manifestation of lichen planus. *Wickham's striae present* - **Wickham's striae** are characteristic **white, lacy reticular patterns** seen on the surface of lichen planus lesions, especially on the oral mucosa and cutaneous papules. - Their presence is a classic diagnostic feature of lichen planus. *Violaceous flat papules* - Cutaneous lesions of lichen planus are typically described as **pruritic, polygonal, planar (flat-topped), purple (violaceous) papules and plaques**. - This classic description helps in the clinical diagnosis of the condition. *Koebner phenomenon positive* - The **Koebner phenomenon**, or isomorphic response, refers to the development of new skin lesions in areas of trauma or injury. - This phenomenon is often observed in lichen planus, where scratching or irritation can precipitate new lesions along the lines of trauma.

Question 319: Which of the following is a typical feature of erythema multiforme?

A. Vesicular eruption
B. Target lesions (Correct Answer)
C. Nikolsky sign
D. Comedonal lesions

Explanation: ***Target lesions*** - **Target lesions**, characterized by concentric rings of varying color (like a "bulls-eye"), are the hallmark dermatological finding in **erythema multiforme**. - These lesions typically appear suddenly, often on the **extremities**, and can be associated with pruritus or burning. *Vesicular eruption* - While vesicles can be seen in some severe forms of erythema multiforme, a **generalized vesicular eruption** is more characteristic of conditions like **herpes simplex infection**, varicella, or shingles. - The primary lesion in typical erythema multiforme is the target lesion, not widespread vesicles. *Nikolsky sign* - The **Nikolsky sign**, which is the dislodging of epidermis by lateral pressure on apparently uninvolved skin, is typically associated with **blistering disorders** like **pemphigus vulgaris** or **toxic epidermal necrolysis (TEN)**. - It is not a feature of erythema multiforme, where the epidermal detachment is usually localized and not easily induced by gentle pressure on healthy skin. *Comedonal lesions* - **Comedonal lesions** (blackheads and whiteheads) are characteristic features of **acne vulgaris**. - They result from blocked pilosebaceous units and are fundamentally different in pathogenesis and appearance from the inflammatory lesions seen in erythema multiforme.

Question 320: A child presents with grouped vesicles on an erythematous base on the buttocks. What is the most likely diagnosis?

A. Bullous impetigo
B. Dermatitis herpetiformis
C. Pemphigus
D. Herpes simplex (Correct Answer)

Explanation: ***Herpes simplex*** - Herpes simplex virus (HSV) classically presents with **grouped vesicles on an erythematous base**, which perfectly matches this clinical presentation. - In **children**, HSV commonly affects the **buttocks** through autoinoculation or direct contact, especially in the diaper area. - The lesions are typically **painful and pruritic**, and may be preceded by tingling or burning sensation. - Diagnosis is confirmed by **Tzanck smear** (multinucleated giant cells), **PCR**, or **viral culture**. - Treatment includes **acyclovir** or other antivirals, especially for severe or recurrent cases. *Dermatitis herpetiformis* - While DH does present with intensely pruritic, grouped vesicles on an erythematous base, it is **extremely rare in children** and typically presents in **adults (3rd-4th decade)**. - Classic sites include **extensor surfaces** (elbows, knees), scalp, and buttocks, but the pediatric presentation makes this diagnosis unlikely. - It is strongly associated with **celiac disease** and responds to **gluten-free diet** and **dapsone**. *Bullous impetigo* - Bullous impetigo presents with **flaccid bullae** that rupture to form **honey-colored crusts**, not grouped vesicles. - It is a **bacterial infection** caused by *Staphylococcus aureus* producing exfoliative toxin. - Common in **young children**, particularly in warm, humid conditions. *Pemphigus* - Pemphigus is **extremely rare in children** and causes **fragile bullae** that easily rupture, leading to erosions. - Typically affects **mucous membranes first** (oral cavity), then skin. - It is an **autoimmune blistering disease** with antibodies against desmoglein, causing intraepidermal acantholysis.

Practice by Chapter

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Cutaneous Histopathology

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Dermatological Procedures

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