Psoriasis — MCQs

Q: A 16-year-old boy presented with asymptomatic, multiple erythematous annular lesions with a collarette of scales at the periphery of the lesions present on the trunk. What is the most likely diagnosis?

Pityriasis rosea. ### Explanation The clinical presentation of multiple erythematous annular lesions with a characteristic **collarette of scales** at the periphery on the trunk is a classic description of **Pityriasis Rosea (PR)**. **Why Pityriasis Rosea is correct:** PR is an acute, self-limiting inflammatory dermatosis, often associated with Human Herpesvirus 6 or 7 (HHV-6/7). It typically begins with a single, large **"Herald Patch"** followed by a generalized eruption of smaller oval lesions. The scales in PR are unique; they are attached at the periphery and free in the center, forming a **"collarette"** appearance. On the back, these lesions follow the lines of cleavage, creating a **"Christmas Tree"** or "Fir Tree" distribution. **Why the other options are incorrect:** * **Pityriasis versicolor:** Presents as hypo- or hyperpigmented macules with fine, branny (furfuraceous) scaling. It is caused by *Malassezia* and does not typically show a peripheral collarette of scales. * **Pityriasis alba:** Commonly seen in children with atopy, presenting as ill-defined hypopigmented patches with fine scaling, usually on the face. It lacks the annular, erythematous nature of PR. * **Pityriasis rubra pilaris (PRP):** Characterized by follicular papules on an erythematous base, "islands of sparing," and orange-red palmoplantar keratoderma. It does not present with a collarette of scales. **High-Yield Clinical Pearls for NEET-PG:** * **Herald Patch:** The initial lesion (seen in 80% of cases), usually larger and more scaly than subsequent lesions. * **Hanging Curtain Sign:** When the skin is stretched across the long axis of the lesion, the scales tend to fold inwards (characteristic of PR). * **Treatment:** Usually conservative (reassurance); antihistamines for pruritus. * **Differential Diagnosis:** Secondary syphilis (always rule this out if lesions involve palms and soles; PR typically spares them).

Q: Civatte bodies are a characteristic histological feature of which condition?

Lichen planus. **Explanation:** **Civatte bodies** (also known as colloid or hyaline bodies) are a hallmark histopathological finding in **Lichen Planus**. They represent apoptotic or degenerated keratinocytes located in the lower epidermis or papillary dermis. **Why Lichen Planus is correct:** Lichen planus is characterized by a "lichenoid" or interface dermatitis where a dense, band-like lymphocytic infiltrate attacks the basal layer of the epidermis. This immune-mediated destruction leads to **liquefactive degeneration** of the basal cells. The shrunken, eosinophilic remnants of these dead keratinocytes are the Civatte bodies. They stain positively for PAS (Periodic Acid-Schiff) and contain IgM on direct immunofluorescence. **Why other options are incorrect:** * **Lichen simplex chronicus:** This is a result of repetitive scratching. Histology shows hyperkeratosis, hypergranulosis, and regular elongation of rete ridges (psoriasiform hyperplasia), but not basal cell apoptosis. * **Lichen sclerosus:** While it involves interface changes, its hallmark is significant subepidermal edema and homogenization of collagen (sclerosis) in the upper dermis, rather than prominent Civatte bodies. **NEET-PG High-Yield Pearls for Lichen Planus:** * **6 P’s:** Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. * **Wickham Striae:** White reticular lines on the surface of lesions (due to focal hypergranulosis). * **Max-Joseph Spaces:** Small clefts between the epidermis and dermis due to extensive basal cell degeneration. * **Saw-tooth Rete Ridges:** Characteristic appearance of the epidermal-dermal junction. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo).

Q: The "Hanging Curtain Sign" is characteristic of which dermatological condition?

Pityriasis Rosea. **Explanation:** The **Hanging Curtain Sign** is a classic clinical feature of **Pityriasis Rosea (PR)**. It is elicited by stretching the skin across the long axis of a herald patch or a secondary lesion. Due to the fine, "cigarette paper" like scaling and the way the scales are attached at the periphery (collarette scaling), the scales fold and hang down like a curtain when the skin is pinched or stretched. **Analysis of Options:** * **Pityriasis Rosea (Correct):** An acute, self-limiting inflammatory dermatosis. It typically begins with a **Herald Patch** (a single, large, erythematous scaly plaque) followed by a generalized eruption in a **"Christmas Tree" distribution** along the lines of cleavage (Langer’s lines). * **Psoriasis:** Characterized by the **Auspitz Sign** (pinpoint bleeding upon removal of scales) and **Grattage Test**. The scales are silvery-white and micaceous, not "curtain-like." * **Lichen Planus:** Known for the **6 P’s** (Planar, Purple, Polygonal, Pruritic, Papules, and Plaques) and **Wickham Striae**. It does not exhibit the hanging curtain sign. * **Hordeolum Externum:** This is an acute focal infection (usually Staphylococcal) of the eyelash follicle or associated glands (Zeis/Moll). It is an ophthalmological condition presenting as a painful eyelid bump, unrelated to scaly dermatoses. **High-Yield Clinical Pearls for NEET-PG:** * **Collarette of scales:** Scales in PR are attached at the periphery with free central edges. * **Herald Patch:** The initial lesion seen in 50-90% of cases. * **Etiology:** Associated with **HHV-6 and HHV-7** reactivation. * **Treatment:** Usually self-limiting (6-8 weeks); symptomatic relief with antihistamines or topical steroids.

Q: What is the most common cause of psoriasis?

Autoimmune. **Explanation:** Psoriasis is fundamentally defined as a **chronic, T-cell mediated autoimmune inflammatory dermatosis**. The core pathophysiology involves the activation of the **IL-23/Th17 axis**, where dendritic cells and T-lymphocytes (specifically Th1 and Th17) release cytokines like TNF-α, IL-17, and IL-22. This "cytokine storm" triggers the rapid, uncontrolled proliferation of keratinocytes, leading to the characteristic thickened, scaly plaques. **Analysis of Options:** * **A. Autoimmune (Correct):** While the exact trigger is often unknown, the disease is driven by an aberrant immune response against self-antigens (like LL-37 or ADAMTSL5) in the skin. * **B. Hereditary:** Genetics play a significant role (e.g., **HLA-Cw6** is the strongest association), but it is considered a predisposing factor rather than the direct "cause." Not everyone with the gene develops the disease. * **C. Psychosomatic:** Stress is a well-known **trigger** or exacerbating factor for flares, but it does not cause the underlying pathology. * **D. Infective:** Certain infections (like Streptococcal pharyngitis) can trigger **Guttate psoriasis**, but the disease itself is not contagious or primarily infectious. **NEET-PG High-Yield Pearls:** * **Auspitz Sign:** Pinpoint bleeding after scraping a scale (due to thinning of suprapapillary epidermis). * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Vitiligo and Lichen Planus). * **Histology:** Look for **Munro’s microabscesses** (neutrophils in the stratum corneum) and **Kogoj’s pustules** (neutrophils in the stratum spinosum). * **Drug Triggers:** Beta-blockers, Lithium, Antimalarials, and NSAIDs (Mnemonic: **BLANS**).

Q: Which of the following drugs is NOT used in the management of psoriasis?

Chloroquine. In the management of psoriasis, the goal is to inhibit keratinocyte proliferation and modulate the immune response. **Why Chloroquine is the correct answer:** Chloroquine (and Hydroxychloroquine) is an antimalarial drug that is notoriously known to **exacerbate or trigger psoriasis**. It can induce a flare-up of stable plaque psoriasis or even precipitate a life-threatening **erythrodermic or pustular transformation**. The mechanism is thought to involve the inhibition of the enzyme transglutaminase and the stimulation of interleukin-8, leading to epidermal hyperproliferation. Therefore, it is strictly avoided in psoriatic patients. **Why the other options are incorrect:** * **Psoralens (Option A):** These are photosensitizing agents used in **PUVA (Psoralen + UVA)** therapy. They intercalate into DNA to inhibit rapid cell division. * **Methotrexate (Option C):** A folic acid antagonist that acts as a potent immunosuppressant and cytotoxin. It is a **gold standard systemic treatment** for severe plaque psoriasis, psoriatic arthritis, and erythrodermic psoriasis. * **Coal Tar (Option D):** One of the oldest topical treatments (e.g., Goeckerman regimen). It has anti-inflammatory and keratoplastic properties that help normalize keratinization. **NEET-PG High-Yield Pearls:** * **Drugs that aggravate psoriasis (mnemonic: B-L-A-C-K):** **B**eta-blockers, **L**ithium, **A**ntimalarials (Chloroquine), **C**orticosteroids (withdrawal), and **K** (Potassium) sparing diuretics/NSAIDs. * **First-line for localized psoriasis:** Topical Vitamin D3 analogues (Calcipotriol) and Corticosteroids. * **Drug of choice for Psoriatic Arthritis:** Methotrexate (though biologics like Secukinumab are increasingly used).

Q: Which among the following is the most common site affected by psoriasis?

Extensor surface. **Explanation:** Psoriasis is a chronic, immune-mediated inflammatory skin disorder characterized by well-demarcated erythematous plaques with silvery-white scales. **Why Extensor Surfaces are Correct:** The hallmark of chronic plaque psoriasis (the most common clinical variant) is its predilection for **extensor surfaces**. The most frequently involved sites are the **elbows, knees, and the scalp**. This distribution is attributed to the **Koebner phenomenon**, where skin lesions appear at sites of repetitive minor trauma or friction, which occurs more frequently on extensor surfaces. **Analysis of Incorrect Options:** * **Flexor surfaces:** Involvement of flexural areas (axilla, groin, submammary folds) is known as **Inverse Psoriasis**. It is less common and characterized by a lack of scaling due to moisture in the skin folds. * **Palms and soles:** While Palmoplantar Psoriasis is a recognized variant, it is significantly less common than the classic plaque type involving extensors. * **Oral mucosa:** Psoriasis rarely involves the oral mucosa. When it does, it may manifest as geographic tongue, but it is never the most common site. **High-Yield Clinical Pearls for NEET-PG:** * **Auspitz Sign:** Pinpoint bleeding upon removal of scales (due to thinning of the suprapapillary plate and dilated capillaries). * **Munro’s Microabscess:** Collection of neutrophils in the stratum corneum (pathognomonic histopathology). * **Grattage Test:** Scraping the lesion increases the visibility of silvery scales (candle grease sign). * **Woronoff’s Ring:** A pale halo of blanched skin surrounding a healing psoriatic plaque.

Q: Which of the following conditions produces pre-malignant lesions?

Lichen planus. **Explanation:** The correct answer is **Lichen planus (LP)**. This is because certain variants of Lichen planus, particularly **Oral Lichen Planus (OLP)** and **Vulvar Lichen Planus**, are recognized as **premalignant (potentially malignant) conditions**. Chronic inflammation and rapid cell turnover in these lesions can lead to the development of **Squamous Cell Carcinoma (SCC)**. The risk is highest in the erosive or atrophic subtypes of OLP, with a transformation rate of approximately 0.5% to 2%. **Why other options are incorrect:** * **Psoriasis:** Despite being a chronic inflammatory condition with rapid epidermal hyperplasia, psoriasis is **not** considered a premalignant condition. In fact, some studies suggest a lower incidence of skin cancer within psoriatic plaques themselves, though treatments like PUVA or methotrexate may independently increase malignancy risk. * **Erythema Multiforme:** This is an acute, self-limiting hypersensitivity reaction (often triggered by HSV or drugs). It does not involve chronic tissue remodeling or long-term cellular atypia, and thus carries no risk of malignant transformation. **High-Yield Clinical Pearls for NEET-PG:** * **Lichen Planus:** Characterized by the "6 Ps": Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. Look for **Wickham striae** (white reticular patterns). * **Koebner Phenomenon:** Seen in both Psoriasis and Lichen Planus (development of lesions at sites of trauma). * **Other Premalignant Skin Conditions:** Actinic keratosis (most common), Bowen’s disease, Leukoplakia, and Xeroderma pigmentosum. * **Histopathology of LP:** "Saw-tooth" appearance of rete pegs and basal cell degeneration (liquefaction degeneration).

Q: Which of the following conditions is characterized by the term 'Acanthosis nigricans'?

Psoriasis. **Explanation:** The term **Acanthosis** refers to the diffuse hyperplasia (thickening) of the stratum spinosum layer of the epidermis. In **Psoriasis**, this is a hallmark histopathological feature. Specifically, Psoriasis exhibits **regular elongation of rete ridges** (often described as "test-tube in a rack" appearance) due to the rapid turnover of keratinocytes. **Analysis of Options:** * **Psoriasis (Correct):** The histopathology is characterized by the triad of **Acanthosis**, **Parakeratosis** (retention of nuclei in the stratum corneum), and **Munro’s microabscesses** (neutrophils in the parakeratotic stratum corneum). * **Dermatomyositis:** Characterized by interface dermatitis, vacuolar degeneration of the basal layer, and dermal mucin. Clinical hallmarks include Gottron papules and Heliotrope rash. * **Systemic Lupus Erythematosus (SLE):** Shows liquefactive degeneration of the basal cell layer and follicular plugging, but not the regular acanthosis seen in psoriasis. * **Tinea versicolor:** A fungal infection (Malassezia) characterized by "spaghetti and meatballs" appearance on KOH mount; histopathology shows minimal epidermal change, primarily hyphae and spores in the stratum corneum. **High-Yield Clinical Pearls for NEET-PG:** * **Acanthosis Nigricans vs. Acanthosis:** Do not confuse "Acanthosis" (a histological term) with "Acanthosis Nigricans" (a clinical condition of hyperpigmented velvety plaques associated with insulin resistance or malignancy). * **Auspitz Sign:** Pinpoint bleeding when psoriasis scales are removed, due to thinning of the suprapapillary plate over dilated capillaries. * **Kogoj’s Pustule:** Neutrophils in the stratum spinosum (seen in pustular psoriasis). * **Grattage Test:** Scraping psoriasis lesions produces a candle-grease-like scale.

Q: What is the definitive indication for systemic steroids in psoriasis?

Impetigo herpetiformis. ### Explanation **Correct Answer: D. Impetigo herpetiformis** **Why it is correct:** Impetigo herpetiformis is a rare, life-threatening variant of **pustular psoriasis occurring during pregnancy** (usually in the third trimester). It is considered a medical emergency due to risks of placental insufficiency, fetal demise, and maternal complications like hypocalcemia or sepsis. While systemic steroids are generally avoided in psoriasis, they are the **first-line systemic treatment** in this specific condition to rapidly control inflammation and protect both the mother and the fetus. **Why the other options are incorrect:** * **A & B (Pustular Psoriasis and Erythroderma):** Systemic steroids are strictly **contraindicated** in these conditions. Although they provide rapid initial clearance, their withdrawal frequently triggers a rebound flare-up, often transforming stable plaque psoriasis into life-threatening generalized pustular psoriasis (Von Zumbusch type). * **C (Psoriatic Arthropathy):** The mainstay of treatment for psoriatic arthritis includes NSAIDs and DMARDs (like Methotrexate or Leflunomide) and biologics (TNF-alpha inhibitors). Systemic steroids are not the definitive treatment and are avoided to prevent skin flares. **High-Yield Clinical Pearls for NEET-PG:** * **The "Steroid Rule":** In dermatology, psoriasis is the classic example where systemic steroids are avoided (except in Impetigo herpetiformis). * **Auspitz Sign:** Pinpoint bleeding on peeling a scale (absent in pustular/erythrodermic variants). * **Woronoff Ring:** A pale halo around a healing psoriasis plaque. * **Drug of Choice for Pustular Psoriasis:** Oral Retinoids (Acitretin) are preferred, but they are strictly contraindicated in pregnancy (teratogenic). This is why steroids are used for Impetigo herpetiformis instead.

Psoriasis Indian Medical PG Practice Questions and MCQs

Question 1: A 16-year-old boy presented with asymptomatic, multiple erythematous annular lesions with a collarette of scales at the periphery of the lesions present on the trunk. What is the most likely diagnosis?

A. Pityriasis versicolor
B. Pityriasis alba
C. Pityriasis rosea (Correct Answer)
D. Pityriasis rubra pilaris

Explanation: ### Explanation The clinical presentation of multiple erythematous annular lesions with a characteristic **collarette of scales** at the periphery on the trunk is a classic description of **Pityriasis Rosea (PR)**. **Why Pityriasis Rosea is correct:** PR is an acute, self-limiting inflammatory dermatosis, often associated with Human Herpesvirus 6 or 7 (HHV-6/7). It typically begins with a single, large **"Herald Patch"** followed by a generalized eruption of smaller oval lesions. The scales in PR are unique; they are attached at the periphery and free in the center, forming a **"collarette"** appearance. On the back, these lesions follow the lines of cleavage, creating a **"Christmas Tree"** or "Fir Tree" distribution. **Why the other options are incorrect:** * **Pityriasis versicolor:** Presents as hypo- or hyperpigmented macules with fine, branny (furfuraceous) scaling. It is caused by *Malassezia* and does not typically show a peripheral collarette of scales. * **Pityriasis alba:** Commonly seen in children with atopy, presenting as ill-defined hypopigmented patches with fine scaling, usually on the face. It lacks the annular, erythematous nature of PR. * **Pityriasis rubra pilaris (PRP):** Characterized by follicular papules on an erythematous base, "islands of sparing," and orange-red palmoplantar keratoderma. It does not present with a collarette of scales. **High-Yield Clinical Pearls for NEET-PG:** * **Herald Patch:** The initial lesion (seen in 80% of cases), usually larger and more scaly than subsequent lesions. * **Hanging Curtain Sign:** When the skin is stretched across the long axis of the lesion, the scales tend to fold inwards (characteristic of PR). * **Treatment:** Usually conservative (reassurance); antihistamines for pruritus. * **Differential Diagnosis:** Secondary syphilis (always rule this out if lesions involve palms and soles; PR typically spares them).

Question 2: Civatte bodies are a characteristic histological feature of which condition?

A. Lichen simplex chronicus
B. Lichen planus (Correct Answer)
C. Lichen sclerosus
D. All of the above

Explanation: **Explanation:** **Civatte bodies** (also known as colloid or hyaline bodies) are a hallmark histopathological finding in **Lichen Planus**. They represent apoptotic or degenerated keratinocytes located in the lower epidermis or papillary dermis. **Why Lichen Planus is correct:** Lichen planus is characterized by a "lichenoid" or interface dermatitis where a dense, band-like lymphocytic infiltrate attacks the basal layer of the epidermis. This immune-mediated destruction leads to **liquefactive degeneration** of the basal cells. The shrunken, eosinophilic remnants of these dead keratinocytes are the Civatte bodies. They stain positively for PAS (Periodic Acid-Schiff) and contain IgM on direct immunofluorescence. **Why other options are incorrect:** * **Lichen simplex chronicus:** This is a result of repetitive scratching. Histology shows hyperkeratosis, hypergranulosis, and regular elongation of rete ridges (psoriasiform hyperplasia), but not basal cell apoptosis. * **Lichen sclerosus:** While it involves interface changes, its hallmark is significant subepidermal edema and homogenization of collagen (sclerosis) in the upper dermis, rather than prominent Civatte bodies. **NEET-PG High-Yield Pearls for Lichen Planus:** * **6 P’s:** Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. * **Wickham Striae:** White reticular lines on the surface of lesions (due to focal hypergranulosis). * **Max-Joseph Spaces:** Small clefts between the epidermis and dermis due to extensive basal cell degeneration. * **Saw-tooth Rete Ridges:** Characteristic appearance of the epidermal-dermal junction. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo).

Question 3: The "Hanging Curtain Sign" is characteristic of which dermatological condition?

A. Hordeolum externum
B. Psoriasis
C. Lichen Planus
D. Pityriasis Rosea (Correct Answer)

Explanation: **Explanation:** The **Hanging Curtain Sign** is a classic clinical feature of **Pityriasis Rosea (PR)**. It is elicited by stretching the skin across the long axis of a herald patch or a secondary lesion. Due to the fine, "cigarette paper" like scaling and the way the scales are attached at the periphery (collarette scaling), the scales fold and hang down like a curtain when the skin is pinched or stretched. **Analysis of Options:** * **Pityriasis Rosea (Correct):** An acute, self-limiting inflammatory dermatosis. It typically begins with a **Herald Patch** (a single, large, erythematous scaly plaque) followed by a generalized eruption in a **"Christmas Tree" distribution** along the lines of cleavage (Langer’s lines). * **Psoriasis:** Characterized by the **Auspitz Sign** (pinpoint bleeding upon removal of scales) and **Grattage Test**. The scales are silvery-white and micaceous, not "curtain-like." * **Lichen Planus:** Known for the **6 P’s** (Planar, Purple, Polygonal, Pruritic, Papules, and Plaques) and **Wickham Striae**. It does not exhibit the hanging curtain sign. * **Hordeolum Externum:** This is an acute focal infection (usually Staphylococcal) of the eyelash follicle or associated glands (Zeis/Moll). It is an ophthalmological condition presenting as a painful eyelid bump, unrelated to scaly dermatoses. **High-Yield Clinical Pearls for NEET-PG:** * **Collarette of scales:** Scales in PR are attached at the periphery with free central edges. * **Herald Patch:** The initial lesion seen in 50-90% of cases. * **Etiology:** Associated with **HHV-6 and HHV-7** reactivation. * **Treatment:** Usually self-limiting (6-8 weeks); symptomatic relief with antihistamines or topical steroids.

Question 4: What is the most common cause of psoriasis?

A. Autoimmune (Correct Answer)
B. Hereditary
C. Psychosomatic
D. Infective

Explanation: **Explanation:** Psoriasis is fundamentally defined as a **chronic, T-cell mediated autoimmune inflammatory dermatosis**. The core pathophysiology involves the activation of the **IL-23/Th17 axis**, where dendritic cells and T-lymphocytes (specifically Th1 and Th17) release cytokines like TNF-α, IL-17, and IL-22. This "cytokine storm" triggers the rapid, uncontrolled proliferation of keratinocytes, leading to the characteristic thickened, scaly plaques. **Analysis of Options:** * **A. Autoimmune (Correct):** While the exact trigger is often unknown, the disease is driven by an aberrant immune response against self-antigens (like LL-37 or ADAMTSL5) in the skin. * **B. Hereditary:** Genetics play a significant role (e.g., **HLA-Cw6** is the strongest association), but it is considered a predisposing factor rather than the direct "cause." Not everyone with the gene develops the disease. * **C. Psychosomatic:** Stress is a well-known **trigger** or exacerbating factor for flares, but it does not cause the underlying pathology. * **D. Infective:** Certain infections (like Streptococcal pharyngitis) can trigger **Guttate psoriasis**, but the disease itself is not contagious or primarily infectious. **NEET-PG High-Yield Pearls:** * **Auspitz Sign:** Pinpoint bleeding after scraping a scale (due to thinning of suprapapillary epidermis). * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Vitiligo and Lichen Planus). * **Histology:** Look for **Munro’s microabscesses** (neutrophils in the stratum corneum) and **Kogoj’s pustules** (neutrophils in the stratum spinosum). * **Drug Triggers:** Beta-blockers, Lithium, Antimalarials, and NSAIDs (Mnemonic: **BLANS**).

Question 5: Which of the following drugs is NOT used in the management of psoriasis?

A. Psoralens
B. Chloroquine (Correct Answer)
C. Methotrexate
D. Coaltar

Explanation: In the management of psoriasis, the goal is to inhibit keratinocyte proliferation and modulate the immune response. **Why Chloroquine is the correct answer:** Chloroquine (and Hydroxychloroquine) is an antimalarial drug that is notoriously known to **exacerbate or trigger psoriasis**. It can induce a flare-up of stable plaque psoriasis or even precipitate a life-threatening **erythrodermic or pustular transformation**. The mechanism is thought to involve the inhibition of the enzyme transglutaminase and the stimulation of interleukin-8, leading to epidermal hyperproliferation. Therefore, it is strictly avoided in psoriatic patients. **Why the other options are incorrect:** * **Psoralens (Option A):** These are photosensitizing agents used in **PUVA (Psoralen + UVA)** therapy. They intercalate into DNA to inhibit rapid cell division. * **Methotrexate (Option C):** A folic acid antagonist that acts as a potent immunosuppressant and cytotoxin. It is a **gold standard systemic treatment** for severe plaque psoriasis, psoriatic arthritis, and erythrodermic psoriasis. * **Coal Tar (Option D):** One of the oldest topical treatments (e.g., Goeckerman regimen). It has anti-inflammatory and keratoplastic properties that help normalize keratinization. **NEET-PG High-Yield Pearls:** * **Drugs that aggravate psoriasis (mnemonic: B-L-A-C-K):** **B**eta-blockers, **L**ithium, **A**ntimalarials (Chloroquine), **C**orticosteroids (withdrawal), and **K** (Potassium) sparing diuretics/NSAIDs. * **First-line for localized psoriasis:** Topical Vitamin D3 analogues (Calcipotriol) and Corticosteroids. * **Drug of choice for Psoriatic Arthritis:** Methotrexate (though biologics like Secukinumab are increasingly used).

Question 6: A 24-year-old lady with a past history of psoriasis presents with fever and multiple pustular lesions in a generalized distribution. What is the drug of choice for managing her condition?

A. Corticosteroids
B. Retinoids
C. Methotrexate (Correct Answer)
D. Psoralen with PUVA

Explanation: ### **Explanation** The clinical presentation of fever and generalized pustular lesions in a patient with a history of psoriasis is diagnostic of **Generalized Pustular Psoriasis (Von Zumbusch Psoriasis)**. This is a dermatological emergency characterized by sterile pustules on an erythematous base, often triggered by the withdrawal of systemic steroids, infections, or pregnancy. **1. Why Methotrexate is the Correct Answer:** Methotrexate is considered the **first-line systemic treatment** for Generalized Pustular Psoriasis (GPP) in non-pregnant adults. It works by inhibiting dihydrofolate reductase, thereby reducing the rapid epidermal cell turnover and exerting a potent anti-inflammatory effect. It is highly effective in achieving rapid clearance of pustules and stabilizing the patient's systemic symptoms. **2. Analysis of Incorrect Options:** * **Corticosteroids (Option A):** While they may provide temporary relief, systemic steroids are generally **avoided** in psoriasis. Their withdrawal is the most common trigger for precipitating a life-threatening pustular flare (rebound phenomenon). * **Retinoids (Option B):** Oral retinoids (like Acitretin) are highly effective for GPP and are often considered a first-line choice. However, in the context of a **24-year-old lady** (reproductive age), they are avoided due to their significant **teratogenic potential** and long half-life (requiring contraception for 3 years post-treatment). * **PUVA (Option D):** Phototherapy is contraindicated in the acute phase of GPP as it can worsen the inflammatory state and is impractical for a patient with systemic symptoms like fever. **3. NEET-PG High-Yield Pearls:** * **Histopathology:** Look for **Kogoj’s spongiform pustules** (neutrophils in the stratum spinosum) and **Munro’s microabscesses** (neutrophils in the stratum corneum). * **Trigger:** Most common trigger for GPP is the **withdrawal of systemic steroids**. * **Emergency Management:** Always monitor for complications like secondary infections, electrolyte imbalance (hypocalcemia), and high-output heart failure. * **Alternative:** In modern practice, biologicals (like **Infliximab** or **Secukinumab**) are increasingly used for rapid control.

Question 7: Which among the following is the most common site affected by psoriasis?

A. Flexor surface
B. Extensor surface (Correct Answer)
C. Palms and soles
D. Oral mucosa

Explanation: **Explanation:** Psoriasis is a chronic, immune-mediated inflammatory skin disorder characterized by well-demarcated erythematous plaques with silvery-white scales. **Why Extensor Surfaces are Correct:** The hallmark of chronic plaque psoriasis (the most common clinical variant) is its predilection for **extensor surfaces**. The most frequently involved sites are the **elbows, knees, and the scalp**. This distribution is attributed to the **Koebner phenomenon**, where skin lesions appear at sites of repetitive minor trauma or friction, which occurs more frequently on extensor surfaces. **Analysis of Incorrect Options:** * **Flexor surfaces:** Involvement of flexural areas (axilla, groin, submammary folds) is known as **Inverse Psoriasis**. It is less common and characterized by a lack of scaling due to moisture in the skin folds. * **Palms and soles:** While Palmoplantar Psoriasis is a recognized variant, it is significantly less common than the classic plaque type involving extensors. * **Oral mucosa:** Psoriasis rarely involves the oral mucosa. When it does, it may manifest as geographic tongue, but it is never the most common site. **High-Yield Clinical Pearls for NEET-PG:** * **Auspitz Sign:** Pinpoint bleeding upon removal of scales (due to thinning of the suprapapillary plate and dilated capillaries). * **Munro’s Microabscess:** Collection of neutrophils in the stratum corneum (pathognomonic histopathology). * **Grattage Test:** Scraping the lesion increases the visibility of silvery scales (candle grease sign). * **Woronoff’s Ring:** A pale halo of blanched skin surrounding a healing psoriatic plaque.

Question 8: Which of the following conditions produces pre-malignant lesions?

A. Psoriasis
B. Erythema multiforme
C. Lichen planus (Correct Answer)
D. All of the above

Explanation: **Explanation:** The correct answer is **Lichen planus (LP)**. This is because certain variants of Lichen planus, particularly **Oral Lichen Planus (OLP)** and **Vulvar Lichen Planus**, are recognized as **premalignant (potentially malignant) conditions**. Chronic inflammation and rapid cell turnover in these lesions can lead to the development of **Squamous Cell Carcinoma (SCC)**. The risk is highest in the erosive or atrophic subtypes of OLP, with a transformation rate of approximately 0.5% to 2%. **Why other options are incorrect:** * **Psoriasis:** Despite being a chronic inflammatory condition with rapid epidermal hyperplasia, psoriasis is **not** considered a premalignant condition. In fact, some studies suggest a lower incidence of skin cancer within psoriatic plaques themselves, though treatments like PUVA or methotrexate may independently increase malignancy risk. * **Erythema Multiforme:** This is an acute, self-limiting hypersensitivity reaction (often triggered by HSV or drugs). It does not involve chronic tissue remodeling or long-term cellular atypia, and thus carries no risk of malignant transformation. **High-Yield Clinical Pearls for NEET-PG:** * **Lichen Planus:** Characterized by the "6 Ps": Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. Look for **Wickham striae** (white reticular patterns). * **Koebner Phenomenon:** Seen in both Psoriasis and Lichen Planus (development of lesions at sites of trauma). * **Other Premalignant Skin Conditions:** Actinic keratosis (most common), Bowen’s disease, Leukoplakia, and Xeroderma pigmentosum. * **Histopathology of LP:** "Saw-tooth" appearance of rete pegs and basal cell degeneration (liquefaction degeneration).

Question 9: Which of the following conditions is characterized by the term 'Acanthosis nigricans'?

A. Dermatomyositis
B. Psoriasis (Correct Answer)
C. Systemic Lupus Erythematosus (SLE)
D. Tinea versicolor

Explanation: **Explanation:** The term **Acanthosis** refers to the diffuse hyperplasia (thickening) of the stratum spinosum layer of the epidermis. In **Psoriasis**, this is a hallmark histopathological feature. Specifically, Psoriasis exhibits **regular elongation of rete ridges** (often described as "test-tube in a rack" appearance) due to the rapid turnover of keratinocytes. **Analysis of Options:** * **Psoriasis (Correct):** The histopathology is characterized by the triad of **Acanthosis**, **Parakeratosis** (retention of nuclei in the stratum corneum), and **Munro’s microabscesses** (neutrophils in the parakeratotic stratum corneum). * **Dermatomyositis:** Characterized by interface dermatitis, vacuolar degeneration of the basal layer, and dermal mucin. Clinical hallmarks include Gottron papules and Heliotrope rash. * **Systemic Lupus Erythematosus (SLE):** Shows liquefactive degeneration of the basal cell layer and follicular plugging, but not the regular acanthosis seen in psoriasis. * **Tinea versicolor:** A fungal infection (Malassezia) characterized by "spaghetti and meatballs" appearance on KOH mount; histopathology shows minimal epidermal change, primarily hyphae and spores in the stratum corneum. **High-Yield Clinical Pearls for NEET-PG:** * **Acanthosis Nigricans vs. Acanthosis:** Do not confuse "Acanthosis" (a histological term) with "Acanthosis Nigricans" (a clinical condition of hyperpigmented velvety plaques associated with insulin resistance or malignancy). * **Auspitz Sign:** Pinpoint bleeding when psoriasis scales are removed, due to thinning of the suprapapillary plate over dilated capillaries. * **Kogoj’s Pustule:** Neutrophils in the stratum spinosum (seen in pustular psoriasis). * **Grattage Test:** Scraping psoriasis lesions produces a candle-grease-like scale.

Question 10: What is the definitive indication for systemic steroids in psoriasis?

A. Pustular psoriasis
B. Erythroderma
C. Psoriatic arthropathy
D. Impetigo herpetiformis (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Impetigo herpetiformis** **Why it is correct:** Impetigo herpetiformis is a rare, life-threatening variant of **pustular psoriasis occurring during pregnancy** (usually in the third trimester). It is considered a medical emergency due to risks of placental insufficiency, fetal demise, and maternal complications like hypocalcemia or sepsis. While systemic steroids are generally avoided in psoriasis, they are the **first-line systemic treatment** in this specific condition to rapidly control inflammation and protect both the mother and the fetus. **Why the other options are incorrect:** * **A & B (Pustular Psoriasis and Erythroderma):** Systemic steroids are strictly **contraindicated** in these conditions. Although they provide rapid initial clearance, their withdrawal frequently triggers a rebound flare-up, often transforming stable plaque psoriasis into life-threatening generalized pustular psoriasis (Von Zumbusch type). * **C (Psoriatic Arthropathy):** The mainstay of treatment for psoriatic arthritis includes NSAIDs and DMARDs (like Methotrexate or Leflunomide) and biologics (TNF-alpha inhibitors). Systemic steroids are not the definitive treatment and are avoided to prevent skin flares. **High-Yield Clinical Pearls for NEET-PG:** * **The "Steroid Rule":** In dermatology, psoriasis is the classic example where systemic steroids are avoided (except in Impetigo herpetiformis). * **Auspitz Sign:** Pinpoint bleeding on peeling a scale (absent in pustular/erythrodermic variants). * **Woronoff Ring:** A pale halo around a healing psoriasis plaque. * **Drug of Choice for Pustular Psoriasis:** Oral Retinoids (Acitretin) are preferred, but they are strictly contraindicated in pregnancy (teratogenic). This is why steroids are used for Impetigo herpetiformis instead.

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Pathophysiology of Psoriasis

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Guttate 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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