Papulosquamous Disorders (Psoriasis, Lichen Planus) MCQs

Dermatology · 34 free questions with answers & explanations.

1. A 32-year-old man has well-defined erythematous plaques with silvery-white scales over elbows and scalp for 5 years. On removing the scales, a bleeding point is seen. Nail examination shows pitting and onycholysis. Which sign describes the bleeding point on scale removal?
2. A 28-year-old HIV-positive man develops sudden onset of multiple small drop-shaped psoriatic lesions over the trunk and limbs following a streptococcal throat infection. What is this clinical variant?
3. A 40-year-old woman with psoriasis presents with fever, generalized skin erythema, and sheets of sterile pustules over the trunk. She had abruptly stopped systemic corticosteroids 5 days ago. What is this feared complication?
4. A 35-year-old woman presents with pruritic, flat-topped, polygonal, violaceous papules over wrists and ankles. Wickham's striae are visible on the surface of papules. There are lacy white streaks in the buccal mucosa. What is the most likely diagnosis?
5. Histopathology of a skin biopsy from a patient with lichen planus shows a 'saw-tooth' pattern of the rete ridges, a band-like lymphocytic infiltrate at the dermoepidermal junction, and eosinophilic hyaline bodies in the basal layer. What are these hyaline bodies called?
6. A 35-year-old with chronic plaque psoriasis is started on methotrexate. Folinic acid is given along with it. What is the rationale for giving folinic acid instead of folic acid?
7. Histopathology of a plaque psoriasis biopsy shows regular epidermal hyperplasia, elongated rete ridges, suprapapillary plate thinning, tortuous papillary vessels, and neutrophilic collections in the stratum corneum. The latter are called:
8. A 40-year-old woman has flat-topped violaceous papules on the flexor wrists. Oral examination shows Wickham striae. Skin biopsy shows a 'saw-tooth' appearance of rete ridges with a dense band-like lymphohistiocytic infiltrate at the DEJ and colloid (Civatte) bodies. These bodies represent:
9. A patient with psoriasis fails topical therapy. Narrow-band UVB (NB-UVB) phototherapy is initiated. Compared to broad-band UVB, NB-UVB (311 nm) has which advantage?
10. In the management of erythrodermic psoriasis, which of the following systemic agents is CONTRAINDICATED due to risk of precipitating flare after withdrawal?
11. Histopathology of psoriasis shows regular elongation of rete ridges, thinning of suprapapillary plates, dilated tortuous capillaries in the dermal papillae, and collections of neutrophils. These neutrophilic collections within the stratum corneum are specifically called:
12. A 40-year-old man with severe psoriasis unresponsive to methotrexate is started on a biologic. He develops recurrent upper respiratory tract infections. Which biologic most likely causes a predisposition to Candida infections due to its specific mechanism?
13. The histopathological finding that differentiates lichen planus from lichenoid drug eruptions is:
14. A patient with lichen planopilaris (LPP) presents with scarring alopecia. Which immunofluorescence finding on scalp biopsy is characteristic?
15. The characteristic histopathological feature of psoriasis that indicates rapid epidermal turnover and premature keratinocyte maturation is:
16. A patient with moderate-to-severe plaque psoriasis failed methotrexate and cyclosporine. A biologic targeting IL-17A is initiated. Which of the following is the correct agent-target pairing?
17. Lichen planus of the nails may cause permanent nail loss (anonychia) when it affects the nail matrix. This occurs due to which specific histological change at the nail matrix?
18. A patient has lichen planus pigmentosus. Unlike classic LP, the DIF finding most commonly seen in LP pigmentosus is:
19. A patient with moderate-to-severe plaque psoriasis not responding to methotrexate is started on a biologic. The agent selectively inhibits IL-17A by binding both free IL-17A and IL-17A already bound to its receptor. This mechanism describes:
20. A 50-year-old man presents with violaceous polygonal flat-topped papules on the wrists. Biopsy shows irregular acanthosis with saw-tooth rete ridges, hypergranulosis, compact orthokeratosis, and band-like lymphohistiocytic infiltrate hugging the DEJ with obscuring the junction. The liquefaction degeneration of basal cells leads to which specific pathological finding?
21. A patient with psoriasis develops asymmetric inflammatory arthritis affecting DIP joints and sacroiliac joints. HLA association and the nail finding most predictive of psoriatic arthritis are respectively:
22. Lichen planopilaris (LPP) is a form of primary scarring alopecia. Which histopathological feature at the isthmus-infundibulum level distinguishes LPP from discoid lupus of the scalp?
23. Psoriatic arthritis (PsA) develops in approximately 30% of patients with psoriasis. The HLA association that strongly predisposes to PsA (particularly the axial/spondyloarthropathy pattern) is:
24. Lichen planus of the nail shows characteristic nail changes. The finding of obliteration of the nail matrix with fusion of the proximal nail fold to the nail bed producing a wing-like scar is called:
25. In psoriasis pathogenesis, the IL-23/Th17 axis is central. Which cell type produces IL-23 (p19/p40 heterodimer) to drive Th17 differentiation and acts as the primary initiator?
26. Lichen planus pigmentosus (LPP) is a prevalent variant in India. Which feature distinguishes LPP from classical lichen planus?
27. The pathomechanism of psoriasis involves which cytokine axis as the central driver of keratinocyte hyperproliferation and plaque formation, making it the target of modern biologics?
28. Oral lichen planus has malignant potential. The variant with HIGHEST risk of malignant transformation is:
29. A patient with pustular psoriasis of von Zumbusch type fails methotrexate. Biologics are considered. Secukinumab, an anti-IL-17A monoclonal antibody, is to be initiated. IL-17A is secreted primarily by which cell type that acts as the key effector in psoriasis pathogenesis?
30. The histopathological hallmark that uniquely distinguishes lichen planus from psoriasis is:
31. A patient with psoriasis shows nail changes: oil-drop discoloration (salmon patches) under the nail plate, onycholysis, and nail pitting. Nail pitting in psoriasis correlates histologically with:
32. A psoriasis patient on methotrexate 15 mg/week develops new tender erythematous erosive lesions at the site of a recent healing surgical incision. This phenomenon is an example of:
33. A 35-year-old woman presents with reticulate lacy white patches on bilateral buccal mucosa and erosive red patches on the tongue. She has purplish flat-topped papules on bilateral wrists. Which investigation best confirms the diagnosis and differentiates this from oral leukoplakia?
34. A psoriasis patient develops a fever with widespread pustulation over erythematous skin covering >70% BSA within 24 hours of stopping a systemic corticosteroid. He is haemodynamically stable. Which gene mutation is most commonly associated with juvenile-onset or recurrent generalised pustular psoriasis (GPP)?