Basic Dermatology Practice Questions

Q: Which Fitzpatrick skin type is most prone to post-inflammatory hyperpigmentation after laser therapy?

Type IV-VI. ***Type IV-VI*** - Individuals with **Fitzpatrick skin types IV-VI** have more active **melanocytes** and higher epidermal melanin, which makes them highly susceptible to **post-inflammatory hyperpigmentation (PIH)** following thermal injury. - In these types, any inflammation from **laser therapy** triggers excessive melanin production, necessitating cautious parameter selection and often pre-treatment with **tyrosinase inhibitors**. *Type I-II* - These skin types (pale white to fair) have minimal melanin and typically **burn rather than tan**, making them more prone to **erythema** but less likely to develop hyperpigmentation. - The risk of PIH is significantly lower compared to darker skin types because their **melanocytes** are less reactive to inflammatory stimuli. *Type V-VI* - While these types are at extremely high risk, this option is less comprehensive than IV-VI in identifying the full range of patients prone to laser complications. - Type V-VI patients specifically carry a high risk for **hypopigmentation** or keloid scarring if laser energy is absorbed excessively by the high baseline **chromophore** density. *Type III-IV* - Type III-IV covers fair to olive skin tones which do carry a moderate risk of PIH, but they are not the *most* prone compared to the category including Type VI. - These types typically tan well but do not represent the highest end of the **melanocyte reactivity** spectrum found in darker skin types.

Q: What is the primary lesion in lichen planus?

Papule. **Explanation:** The primary lesion in **Lichen Planus (LP)** is classically described by the **"6 Ps"**: **P**lanar (flat-topped), **P**urple (violaceous), **P**olygonal, **P**ruritic, **P**apules, and **P**laques. 1. **Why Papule is Correct:** A papule is a solid, raised lesion less than 1 cm in diameter. In LP, the characteristic lesion is a violaceous, flat-topped papule. These papules often coalesce to form larger **plaques**. The surface of these papules typically shows fine, white, lace-like patterns known as **Wickham striae**, which are a hallmark diagnostic feature. 2. **Why Other Options are Incorrect:** * **Macule:** This is a flat, non-palpable change in skin color. While post-inflammatory hyperpigmentation (macules) is common after LP heals, the active primary lesion is always raised. * **Vesicle/Bullae:** These are fluid-filled blisters (vesicles 0.5 cm). While a rare variant called "Bullous Lichen Planus" exists, these are not the *primary* or most common presentation of the disease. **High-Yield Clinical Pearls for NEET-PG:** * **Histopathology:** Look for the "saw-tooth" appearance of rete pegs, basal cell degeneration (liquefaction necrosis), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Koebner Phenomenon:** LP shows a positive Koebner phenomenon (lesions appearing at sites of trauma). * **Associations:** Often associated with **Hepatitis C** infection. * **Civatte Bodies:** These are apoptotic keratinocytes found in the lower epidermis/upper dermis, also known as colloid or cytoid bodies.

Question 1

A 35-year-old man presents with a 2-year history of recurring itchy skin lesions that worsen in winter. His father had a similar condition. Examination reveals Auspitz sign on gentle scraping. The skin findings are shown in Image 1. Which of the following pathophysiological mechanisms is most directly responsible for the sign elicited on scraping in this patient?

Accepted Answer

B. Exposure of dermal papillary capillaries following removal of the suprapapillary epidermal plate in a setting of parakeratosis and thinned granular layer

Answer

A. Loss of cohesion between suprabasal keratinocytes due to autoantibody-mediated desmoglein destruction

Answer

C. Disruption of the dermoepidermal junction with subepidermal cleft formation and mast cell degranulation

Answer

D. Acanthosis with elongated rete ridges and increased transepidermal water loss causing superficial erosions

Question 2

A 9-year-old boy is brought with a 3-week history of patchy hair loss on the scalp associated with mild scaling and broken hair stubs. Several classmates have similar complaints. The school nurse noted the lesions fluoresce under a special lamp. The Wood's lamp examination is shown (Image 1). Which of the following is the most appropriate treatment for this condition?

Accepted Answer

A. Oral griseofulvin for 6–8 weeks with selenium sulfide shampoo

Answer

B. Oral fluconazole for 2 weeks with ketoconazole shampoo

Answer

C. Topical clotrimazole cream applied twice daily for 4 weeks

Answer

D. Oral terbinafine for 4 weeks with povidone-iodine shampoo

Question 3

Which Fitzpatrick skin type is most prone to post-inflammatory hyperpigmentation after laser therapy?

Accepted Answer

Type IV-VI

Answer

Type I-II

Answer

Type V-VI

Answer

Type III-IV

Question 4

A young female presents with a history of fever and a nodular lesion over the shin. Histopathology reveals foamy histiocytes with neutrophilic infiltration. There is no evidence of vasculitis. What is the most probable diagnosis?

Accepted Answer

Erythema nodosum

Answer

Sweet's Syndrome

Answer

Erythema nodosum leprosum

Answer

Behcet's syndrome

Question 5

What is the primary lesion in lichen planus?

Accepted Answer

Papule

Answer

Macule

Answer

Vesicle

Answer

Bullae

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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