Pathophysiology of Psoriasis Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Pathophysiology of Psoriasis. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Pathophysiology of Psoriasis Indian Medical PG Question 1: 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
Pathophysiology of Psoriasis 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.
Pathophysiology of Psoriasis Indian Medical PG Question 2: All are true about psoriasis except –
- A. Auspitz sign positive
- B. Parakeratosis & acanthosis
- C. Joint involvement in 5–10% (Correct Answer)
- D. Pitting of nails
- E. Koebner phenomenon
Pathophysiology of Psoriasis Explanation: ***Joint involvement in 5–10%***
- While **psoriasis** is a skin condition, it can involve the joints in about **30% of patients**, leading to **psoriatic arthritis**.
- Therefore, stating that joint involvement occurs in only **5-10%** is incorrect, as the percentage is significantly higher.
- This is the **FALSE statement** in this EXCEPT question.
*Auspitz sign positive*
- The **Auspitz sign** (pinpoint bleeding when scales are removed) is a classic feature of psoriasis.
- It occurs due to the proximity of dilated capillaries to the thinned suprapapillary epidermis.
- This is a **TRUE statement**.
*Parakeratosis & acanthosis*
- **Parakeratosis** (retention of nuclei in the stratum corneum) and **acanthosis** (epidermal hyperplasia) are classic histopathological features of psoriasis.
- These features reflect the **rapid cell turnover** and **thickening of the epidermis** characteristic of psoriatic plaques.
- This is a **TRUE statement**.
*Pitting of nails*
- **Nail pitting** is a common manifestation of psoriasis, affecting up to **50% of patients** with chronic plaque psoriasis and **80% of patients with psoriatic arthritis**.
- Other nail changes include **onycholysis**, **subungual hyperkeratosis**, and discoloration.
- This is a **TRUE statement**.
*Koebner phenomenon*
- **Koebner phenomenon** (isomorphic response) is the development of psoriatic lesions at sites of trauma or injury.
- This is seen in approximately **25% of patients** with psoriasis and is a well-recognized clinical feature.
- This is a **TRUE statement**.
Pathophysiology of Psoriasis Indian Medical PG Question 3: Which interleukin is specifically secreted by Th17 cells?
- A. IFN Gamma
- B. IL6
- C. IL-17 (Correct Answer)
- D. IL-22
Pathophysiology of Psoriasis Explanation: ***IL22***
- Th17 cells predominantly secrete **IL-17** and also produce **IL-22**, which is significant in mucosal immunity and inflammation [1].
- **IL-22** plays a crucial role in the response to infections and in the pathogenesis of inflammatory diseases.
*IL16*
- IL-16 is primarily associated with **chemoattractant and regulatory functions** for lymphocytes and not directly secreted by Th17 cells.
- It is involved in **eosinophil and T cell activation**, which is not characteristic of the Th17 response.
*IFN Gamma*
- IFN-gamma is mainly produced by **Th1 cells** and is critical for **cell-mediated immunity**, which is distinct from the function of Th17 cells.
- It plays a role in activating **macrophages**, unlike Th17 cells which focus on **neutrophil recruitment** and inflammation.
*IL6*
- While IL-6 is a pro-inflammatory cytokine that can be involved in various immune responses, it is not primarily secreted by Th17 cells.
- It is produced by a variety of cell types including fibroblasts and macrophages, acting as a mediator in the **acute phase response**.
**References:**
[1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 158-160.
Pathophysiology of Psoriasis Indian Medical PG Question 4: Psoriasis is exacerbated by -
- A. Beta-blockers
- B. Lithium
- C. Antimalarials
- D. All of the options (Correct Answer)
Pathophysiology of Psoriasis Explanation: ***All of the above***
- **Beta-blockers**, **lithium**, and **antimalarial drugs** are well-established medications that can exacerbate or trigger psoriasis flares.
- Patients with psoriasis require careful monitoring when these medications are prescribed, with consideration of alternative treatments when feasible.
***Beta-blockers***
- **Non-selective beta-blockers** (particularly propranolol) can worsen existing psoriasis or induce new-onset disease.
- The mechanism likely involves alterations in **T-cell function** and **epidermal proliferation**.
- Risk is higher with non-selective agents compared to cardioselective beta-blockers.
***Lithium***
- **Lithium**, used for bipolar disorder, is a frequent and well-documented psoriasis trigger.
- Can induce or worsen various forms including **plaque psoriasis**, **pustular psoriasis**, and **erythrodermic psoriasis**.
- Exacerbations typically occur within weeks to months of initiation.
***Antimalarials***
- **Chloroquine** and **hydroxychloroquine** can precipitate severe psoriasis flares.
- Particularly associated with **erythrodermic** and **generalized pustular psoriasis**.
- Mechanism involves **immune cell activation** and amplification of inflammatory pathways.
Pathophysiology of Psoriasis Indian Medical PG Question 5: "Isomorphic response" can be a feature of the following except
- A. Tinea (Correct Answer)
- B. Warts
- C. Molluscum contagiosum
- D. Psoriasis
Pathophysiology of Psoriasis Explanation: ***Tinea***
- The **isomorphic response (Koebner phenomenon)** refers to the development of new skin lesions in areas of trauma due to an immunological process.
- This phenomenon is **not typically seen in tinea** (fungal infections).
- While tinea can spread to new areas, this occurs through **direct fungal inoculation and contact spread**, not through the true Koebner mechanism.
*Warts*
- **Warts** caused by human papillomavirus (HPV) can exhibit the **isomorphic response**.
- Trauma to the skin can lead to **viral inoculation** in that area, resulting in new wart formation along lines of trauma.
- This is a well-recognized example of Koebner phenomenon in viral infections.
*Molluscum contagiosum*
- **Molluscum contagiosum** (poxvirus infection) can demonstrate the **isomorphic response**.
- **Scratching or rubbing** can spread the virus to new areas through autoinoculation.
- New lesions develop along the lines of trauma, consistent with Koebner phenomenon.
*Psoriasis*
- **Psoriasis** is the **classic and most well-known** condition exhibiting the isomorphic response or Koebner phenomenon.
- New psoriatic plaques appear in areas of **skin injury** (scratches, cuts, burns, surgical incisions, friction).
- Seen in approximately **25-50%** of psoriasis patients.
Pathophysiology of Psoriasis Indian Medical PG Question 6: The burrow in scabies is in
- A. S. corneum (Correct Answer)
- B. Malpighian layer
- C. S. germinatum
- D. S. granulosum
Pathophysiology of Psoriasis Explanation: ***S. corneum***
- The **burrow** created by the *Sarcoptes scabiei* mite is specifically found within the **stratum corneum** of the epidermis.
- This superficial location allows the mite to feed on **keratinocytes** and deposit eggs, leading to the characteristic rash and intense itching.
- The burrow appears as a **serpiginous tract** and is a pathognomonic finding in scabies.
*Malpighian layer*
- The **Malpighian layer** encompasses the **stratum basale** and **stratum spinosum**, which are deeper layers of the epidermis.
- The scabies mite does not burrow into these deeper, metabolically active layers.
*S. germinatum*
- **Stratum germinativum** is another term for the **stratum basale**, the deepest epidermal layer responsible for cell division.
- The scabies mite creates burrows at a much more superficial level in the stratum corneum.
*S. granulosum*
- The **stratum granulosum** lies between the stratum spinosum and stratum corneum.
- While closer to the surface than the Malpighian layer, scabies burrows are specifically located in the more superficial **stratum corneum**, not the granulosum layer.
Pathophysiology of Psoriasis Indian Medical PG Question 7: Vitamin D analogues (such as calcitriol and calcipotriol) are useful in the treatment of:
- A. Pemphigus
- B. Leprosy
- C. Psoriasis (Correct Answer)
- D. Lichen planus
Pathophysiology of Psoriasis Explanation: ***Psoriasis***
- **Vitamin D analogues** such as calcipotriol and calcitriol help treat psoriasis by **inhibiting keratinocyte proliferation** and promoting their differentiation, reducing scale and plaque formation.
- They also have **anti-inflammatory properties** that help alleviate the characteristic redness and inflammation seen in psoriatic plaques.
- These are commonly used as **topical treatments** for mild to moderate plaque psoriasis.
*Pemphigus*
- This is an **autoimmune blistering disease** characterized by **antibodies against desmoglein**, leading to loss of cell-cell adhesion in the epidermis.
- Treatment primarily involves **systemic corticosteroids** and immunosuppressants, not vitamin D analogues.
*Leprosy*
- **Leprosy** is a chronic infectious disease caused by **Mycobacterium leprae**, primarily affecting the skin, nerves, upper respiratory tract, eyes, and testes.
- Treatment involves **multi-drug therapy (MDT)** with antibiotics like dapsone, rifampicin, and clofazimine, and vitamin D analogues are not indicated.
*Lichen planus*
- **Lichen planus** is a chronic inflammatory condition affecting the skin, hair, nails, and mucous membranes, characterized by **pruritic, polygonal, purple, planar papules and plaques**.
- Treatment typically involves **topical or systemic corticosteroids**, retinoids, or phototherapy, not vitamin D analogues.
Pathophysiology of Psoriasis Indian Medical PG Question 8: A 22-year-old woman presents with multiple tender, erythematous nodules on her shins that developed over the past week. She reports having a sore throat 2 weeks ago. She also complains of joint pain and fatigue. Physical examination reveals raised, red, tender nodules on the anterior surface of both legs. Her temperature is 38.2°C. Which of the following is the most likely diagnosis?
- A. Cellulitis
- B. Erythema nodosum (Correct Answer)
- C. Sweet syndrome
- D. Superficial thrombophlebitis
Pathophysiology of Psoriasis Explanation: ***Erythema nodosum***
- The presentation of **tender, erythematous nodules on the shins**, following a preceding **sore throat**, with associated **joint pain and fatigue**, is highly characteristic of **erythema nodosum**.
- It is a form of **panniculitis** typically triggered by infections (e.g., streptococcal pharyngitis), medications, or systemic diseases.
*Cellulitis*
- Characterized by a **warm, erythematous, swollen area** with poorly defined borders, often accompanied by pain and fever, but typically presents as a diffuse skin infection rather than distinct nodules.
- While fever is present, the **nodular nature** of the lesions and their bilateral, symmetrical distribution are less consistent with cellulitis.
*Sweet syndrome*
- Also known as acute febrile neutrophilic dermatosis, it presents with **tender erythematous plaques or nodules** and **fever**, but typically has a more prominent **neutrophilic infiltrate** histologically.
- Lesions of Sweet syndrome often appear on the **upper extremities, face, or neck**, and while it can affect the shins, the clinical picture here is more classic for erythema nodosum, especially given the history of sore throat.
*Superficial thrombophlebitis*
- Presents as a **palpable, tender, erythematous cord** along the course of a superficial vein, often with localized swelling and warmth.
- The lesions are typically **linear or cord-like**, not discrete nodules scattered over the shins, and are directly related to a thrombosed vein.
Pathophysiology of Psoriasis Indian Medical PG Question 9: 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
Pathophysiology of Psoriasis 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).
Pathophysiology of Psoriasis Indian Medical PG Question 10: 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
Pathophysiology of Psoriasis 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).
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