Psoriasis — MCQs

Psoriasis Indian Medical PG Practice Questions and MCQs

Question 111: Assertion: Vitamin D analogues are effective in psoriasis. Reason: They reduce keratinocyte proliferation

A. Both A & R true, R explains A (Correct Answer)
B. A false R true
C. Both A & R true, R doesn't explain A
D. A true R false

Explanation: ***Both A & R true, R explains A*** - **Vitamin D analogues** (e.g., calcipotriol) are a cornerstone treatment for psoriasis because they effectively modulate **keratinocyte proliferation** and differentiation. - Psoriasis is characterized by the **rapid overgrowth of keratinocytes**, and the antiproliferative effects of vitamin D analogues directly address this pathological hallmark. *A false R true* - This option is incorrect because both the assertion (Vitamin D analogues are effective in psoriasis) and the reason (They reduce keratinocyte proliferation) are individually true. - The effectiveness of vitamin D analogues in treating psoriasis is well-established in dermatological practice. *Both A & R true, R doesn't explain A* - This option is incorrect because the reduction of keratinocyte proliferation is precisely *how* vitamin D analogues exert their therapeutic effect in psoriasis. - The mechanism of action described in the reason directly explains the efficacy mentioned in the assertion. *A true R false* - This option is incorrect because the reason ("They reduce keratinocyte proliferation") is a fundamental and well-understood mechanism by which vitamin D analogues work in psoriasis. - Vitamin D analogues bind to vitamin D receptors in keratinocytes, influencing gene expression to inhibit their excessive growth.

Question 112: How does narrowband UVB therapy work in psoriasis?

A. Melanin synthesis
B. Collagen breakdown
C. Keratinocyte proliferation
D. T cell apoptosis (Correct Answer)

Explanation: ***T cell apoptosis*** - Narrowband UVB (NB-UVB) therapy primarily works by inducing **apoptosis (programmed cell death)** of activated **T-lymphocytes** in the psoriatic skin lesions. - By reducing the number of these inflammatory cells, NB-UVB helps to suppress the immune response that drives the **excessive keratinocyte proliferation** in psoriasis. *Melanin synthesis* - While UV radiation does stimulate **melanin synthesis**, leading to tanning, this is a secondary effect and not the primary therapeutic mechanism for psoriasis. - Increased melanin helps protect the skin from UV damage but does not directly treat the underlying pathology of psoriasis. *Collagen breakdown* - UV radiation, especially UVA, can contribute to **collagen breakdown** and photodamage over time, but this is an adverse effect, not a therapeutic mechanism for psoriasis. - Psoriasis treatment aims to normalize skin cell growth and reduce inflammation, not degrade collagen. *Keratinocyte proliferation* - Psoriasis is characterized by **accelerated keratinocyte proliferation**; NB-UVB therapy aims to *reduce* this proliferation, not promote it. - The mechanism by which NB-UVB achieves this reduction is primarily through its effects on immune cells, not by directly enhancing keratinocyte growth.

Question 113: What histological feature is most characteristic of psoriasis?

A. Parakeratosis with retained nuclei in stratum corneum
B. Munro microabscesses in stratum corneum (Correct Answer)
C. Acanthosis with elongated rete ridges
D. Spongiform pustules of Kogoj in stratum spinosum

Explanation: ***Munro microabscesses in stratum corneum*** - Munro microabscesses are characteristic accumulations of **neutrophils** within the **stratum corneum** in psoriasis. - Their presence is a key **histological feature** used in the diagnosis of psoriasis. *Parakeratosis with retained nuclei in stratum corneum* - **Parakeratosis** (retained nuclei in the stratum corneum) is a feature of psoriasis but is **not specific** to it; it can be seen in other inflammatory skin conditions. - While present, it doesn't serve as the sole or most definitive characteristic feature differentiating psoriasis from other conditions. *Acanthosis with elongated rete ridges* - **Acanthosis** (epidermal hyperplasia) with elongated rete ridges is a prominent histological finding in psoriasis. - However, similar epidermal changes can be observed in various other chronic inflammatory skin conditions, making it **less specific** than Munro microabscesses. *Spongiform pustules of Kogoj in stratum spinosum* - **Spongiform pustules of Kogoj** are collections of neutrophils predominantly found in the **stratum spinosum**. - While associated with some forms of psoriasis, particularly **pustular psoriasis**, they are not considered the universally characteristic feature of typical plaque psoriasis.

Question 114: A 54-year-old man presents with well-demarcated, erythematous plaques covered with silvery-white scales on the extensor surfaces of his elbows and knees. What is the most likely diagnosis?

A. Pityriasis rosea
B. Psoriasis (Correct Answer)
C. Eczema
D. Lichen planus

Explanation: ***Psoriasis*** - **Psoriasis** classically presents with **scaly plaques** that often appear on the **extensor surfaces** such as the elbows and knees. - The scales are typically silvery-white and can be itchy or painful, consistent with the characteristic presentation of chronic plaque psoriasis. *Pityriasis rosea* - This condition presents with a **herald patch** followed by smaller, oval, pinkish-red patches with fine scales, often distributed in a **Christmas tree pattern** on the trunk. - It primarily affects the trunk and proximal extremities, rarely involving the extensor surfaces in the same way as psoriasis. *Eczema* - **Eczema**, particularly atopic dermatitis, typically presents with **itchy, erythematous patches** that are often ill-defined and can be dry or weeping. - While it can occur on extensor surfaces, it is more commonly found on flexural surfaces in adults and lacks the distinct, thick silvery scales characteristic of psoriasis. *Lichen planus* - **Lichen planus** is characterized by **pruritic, purple, polygonal, planar papules and plaques** (**the 6 P's**). - It usually affects the flexural surfaces, wrists, ankles, and oral mucosa, rather than predominantly presenting as scaly plaques on extensor surfaces.

Question 115: A 40-year-old male presents with erythematous scaly lesions on the extensor surfaces of his elbows and knees. The clinical diagnosis is confirmed by which sign?

A. Auspitz sign (Correct Answer)
B. KOH smear
C. Tzanck smear
D. Skin biopsy

Explanation: ***Auspitz sign*** - The presence of **erythematous scaly lesions on extensor surfaces** is highly suggestive of **psoriasis**. - The **Auspitz sign** is specific to psoriasis; it refers to pinpoint bleeding after scaling is removed due to exposure of dilated capillaries in dermal papillae. *KOH smear* - A **KOH smear** is used to identify fungal elements in skin, hair, or nails. - It would be relevant if fungal infection were suspected, but not for the clinical picture of psoriasis. *Tzanck smear* - A **Tzanck smear** is used to detect multinucleated giant cells characteristic of herpes simplex or varicella-zoster virus infections. - It is not indicated for the diagnosis of psoriasis. *Skin biopsy* - While a **skin biopsy** can confirm psoriasis, it is typically reserved for atypical presentations or equivocal clinical findings. - The **Auspitz sign** provides a more immediate and clinically specific diagnostic confirmation for classic psoriasis lesions.

Question 116: A 60-year-old woman presents with pruritic, erythematous plaques on her elbows and knees. A skin biopsy shows hyperkeratosis, parakeratosis, and neutrophils in the stratum corneum. What is the diagnosis?

A. Psoriasis (Correct Answer)
B. Atopic dermatitis
C. Lichen planus
D. Seborrheic dermatitis

Explanation: ***Psoriasis*** - The presentation of **pruritic, erythematous plaques** on the **extensor surfaces** (elbows and knees) is classic for **psoriasis**. - Histopathological findings of **hyperkeratosis**, **parakeratosis**, and **neutrophils in the stratum corneum** (Munro microabscesses) are characteristic of psoriasis. *Atopic dermatitis* - Typically presents with **pruritic, eczematous lesions** in flexural areas (e.g., antecubital and popliteal fossae), not usually on extensor surfaces. - Histology would show **spongiosis** (intercellular edema in the epidermis) and **lymphocytic infiltrate**, not prominent neutrophils in the stratum corneum. *Lichen planus* - Characterized by **pruritic, polygonal, purple, planar papules and plaques** (the "6 Ps"), often affecting the wrists, ankles, and oral mucosa. - Histology typically reveals a **sawtooth rete ridge pattern** and a **band-like lymphocytic infiltrate** at the dermo-epidermal junction. *Seborrheic dermatitis* - Usually presents with **greasy, yellowish scales** on erythematous skin in areas rich in sebaceous glands, such as the scalp, face, and chest. - Histology would show **spongiosis**, **psoriasiform hyperplasia**, and a **perivascular lymphocytic infiltrate** with **neutrophils around follicular openings**.

Question 117: A 50-year-old female presents with thickened, hyperkeratotic plaques on her palms and soles, accompanied by a positive Auspitz sign. What is the diagnosis?

A. Palmoplantar psoriasis (Correct Answer)
B. Eczema
C. Lichen planus
D. Pityriasis rubra pilaris

Explanation: ***Palmoplantar psoriasis*** - This condition is characterized by **thickened, hyperkeratotic plaques** specifically on the **palms and soles**. - A **positive Auspitz sign** (pinpoint bleeding after scaling is removed) is a classic finding in **psoriasis**, further supporting this diagnosis. *Eczema* - While eczema can affect the palms and soles (dyshidrotic eczema), it typically presents with **vesicles, intense itching, redness**, and less defined plaques. - The **Auspitz sign is not present** in eczema. *Lichen planus* - Characterized by **pruritic, purple, polygonal, planar papules and plaques** (the 6 Ps), often on the flexural surfaces, wrists, and ankles. - It does not typically present with the specific hyperkeratotic plaques of palmoplantar psoriasis, nor does it have a positive Auspitz sign. *Pityriasis rubra pilaris* - This condition presents with **follicular papules** that coalesce into **salmon-colored plaques** with islands of unaffected skin. - It often involves generalized erythema and scaling but does not typically present as sharply demarcated hyperkeratotic plaques on the palms and soles, nor does it have a positive Auspitz sign.

Question 118: A 45-year-old woman presents with chronic plaques on her elbows and knees accompanied by silvery scales. What is the most appropriate first-line treatment?

A. Topical steroids (Correct Answer)
B. Oral antibiotics
C. Phototherapy
D. Systemic retinoids

Explanation: **Topical Steroids** - For localized, chronic plaques like those seen in **psoriasis** on the elbows and knees, **topical corticosteroids** are the first-line treatment due to their anti-inflammatory properties. - They help reduce **redness, scaling, and itching**, providing effective symptom control for mild to moderate cases. *Oral Antibiotics* - **Oral antibiotics** are used to treat bacterial infections and have no role in the management of psoriasis, which is an **autoimmune inflammatory condition**. - There is no indication of infection (e.g., pus, fever, rapidly spreading cellulitis) in this presentation. *Phototherapy* - **Phototherapy** (e.g., UVB or PUVA) is an effective treatment for widespread or more severe psoriasis, but it is typically reserved when **topical therapies** are insufficient. - It is not usually considered the **first-line treatment** for localized plaques on elbows and knees. *Systemic Retinoids* - **Systemic retinoids** (like acitretin) are potent medications used for severe, widespread, or disabling psoriasis, especially pustular or erythrodermic forms. - They have significant **side effects** and require careful monitoring, making them unsuitable as a first-line treatment for localized plaques.

Question 119: A 50-year-old man presents with red, scaly patches on his scalp that bleed when scratched. This is indicative of which condition?

A. Psoriasis (Correct Answer)
B. Seborrheic dermatitis
C. Tinea capitis
D. Lichen planus

Explanation: ***Psoriasis*** - **Red, scaly patches** on the scalp, especially those that **bleed when scratched** (Auspitz sign), are classic signs of **psoriasis**. - Psoriasis is a **chronic autoimmune** skin condition characterized by accelerated skin cell turnover. *Seborrheic dermatitis* - Presents with **greasy, yellowish scales** and redness, often found in areas with high sebaceous gland activity like the scalp. - Unlike psoriasis, it typically does not exhibit significant bleeding when scratched. *Tinea capitis* - This is a **fungal infection** of the scalp, characterized by **scaly patches**, **hair loss**, and sometimes **black dots** from broken hairs. - It is often associated with itching but usually does not involve the prominent bleeding seen in psoriasis. *Lichen planus* - Characterized by **purplish, polygonal, planar, pruritic papules** and plaques, often on the flexor surfaces, but can affect the scalp. - Scalp involvement, known as lichen planopilaris, typically leads to **scarring alopecia** and does not present with red, scaly patches that bleed easily upon scratching.

Question 120: A 40-year-old male presents with chronic, relapsing pustular eruptions on the palms and soles, along with a history of smoking. What is the most likely diagnosis?

A. Pustular psoriasis
B. Dyshidrotic eczema
C. Palmoplantar pustulosis (Correct Answer)
D. Contact dermatitis

Explanation: ***Palmoplantar pustulosis*** - This condition is characterized by **chronic, relapsing sterile pustules** localized to the **palms and soles**, often associated with a history of **smoking**. - It is now considered a **distinct entity** separate from psoriasis, though it was historically classified as a variant of pustular psoriasis. The strong smoking association and typical palmoplantar distribution are key diagnostic features. *Pustular psoriasis* - Generalized pustular psoriasis presents with **widespread pustules** on erythematous skin beyond the palms and soles and can be accompanied by systemic symptoms such as fever and malaise. - Unlike palmoplantar pustulosis, it typically has a more acute presentation and lacks the exclusive palmoplantar distribution. *Dyshidrotic eczema* - Characterized by **deep-seated vesicles** (not true pustules) on the palms and soles, often intensely itchy. - Lesions are primarily **vesicular** before they rupture or dry, and lack the strong association with **smoking** seen in palmoplantar pustulosis. *Contact dermatitis* - Results from an **allergic or irritant reaction** to an external substance, leading to eczema, erythema, and vesicles in areas of contact. - Would typically have an **identifiable trigger** and would not primarily manifest as **sterile pustules** recurring chronically without clear exposure history.

Practice by Chapter

Pathophysiology of Psoriasis

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Psoriasis Vulgaris

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Guttate Psoriasis

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Erythrodermic Psoriasis

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Pustular Psoriasis

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Palmoplantar Psoriasis

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Nail Psoriasis

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Scalp Psoriasis

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Psoriatic Arthritis

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Topical Therapy for Psoriasis

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Systemic Therapy for Psoriasis

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Phototherapy and Biologics for Psoriasis

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Psoriasis — MCQs

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