Basic Dermatology Practice Questions

Q: During tattooing, in which layer of the skin is the pigment/ink primarily deposited?

Dermis. ***Dermis*** - The **dermis** is the stable layer of the skin that lies beneath the epidermis, containing an extracellular matrix of **collagen and elastin** that anchors the ink particles. - Because the dermis does not undergo the continuous **desquamation** (shedding) process like the epidermis, tattoo ink remains permanently trapped within **dermal fibroblasts** and **macrophages**. *Epidermis* - The epidermis, specifically the **stratum corneum**, constantly sheds cells; ink placed here would be lost within a few weeks as the skin regenerates. - Tattoo needles are specifically designed to penetrate through the epidermis to reach the underlying **dermal layer**. *Subcutaneous tissue* - While some ink may inadvertently reach the **subcutaneous tissue (hypodermis)**, deposition here results in a

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.

Q: A 22-year-old female presents with dry papules in the seborrheic areas, especially in the summer. Her father also has a history of similar lesions. What is the most probable diagnosis?

Darier's disease. ### Explanation **Correct Answer: C. Darier’s Disease** **Why it is correct:** Darier’s disease (Keratosis Follicularis) is an autosomal dominant genodermatosis caused by a mutation in the **ATP2A2 gene**, which encodes the **SERCA2 calcium pump**. This defect leads to a loss of cell-to-cell adhesion (acantholysis) and abnormal keratinization. * **Clinical Presentation:** It typically manifests as greasy, crusted, "dirty-looking" **malodorous papules** in a **seborrheic distribution** (chest, back, forehead, and scalp). * **Exacerbating Factors:** A classic hallmark is **photo-exacerbation**; lesions characteristically flare up during the **summer** due to heat, humidity, and UV exposure. The positive family history in this case further supports an inherited condition. **Why the other options are incorrect:** * **A. Pemphigus foliaceus:** While it involves acantholysis and affects seborrheic areas, it presents with superficial blisters and erosions rather than persistent keratotic papules, and it lacks a strong genetic/hereditary pattern. * **B. Keratosis pilaris:** Presents as "goose-flesh" papules on the extensor surfaces of arms and thighs. It is not typically found in seborrheic areas and does not flare specifically with summer heat. * **D. Seborrheic dermatitis:** Though it occurs in the same distribution, it presents as erythematous plaques with greasy yellow scales (dandruff-like) rather than discrete keratotic papules, and it usually improves or remains stable in summer rather than worsening. **High-Yield Clinical Pearls for NEET-PG:** * **Nail Findings:** Pathognomonic **"V-shaped" nicking** at the distal margin and longitudinal red/white bands. * **Mucosal Findings:** "Cobblestone" appearance of the oral mucosa. * **Histopathology:** Look for **"Corps ronds"** (in the stratum spinosum) and **"Grains"** (in the stratum corneum). * **Hand Findings:** Palmar pits and punctate keratosis.

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: Which of the following is not a type of leukoplakia?

Bullous. **Explanation:** **Leukoplakia** is clinically defined as a "predominantly white patch or plaque of the oral mucosa that cannot be characterized clinically or pathologically as any other disease." It is a premalignant condition. **Why Bullous is the correct answer:** Leukoplakia is classified based on its clinical morphology into **Homogenous** and **Non-homogenous** types. **Bullous** is not a recognized clinical variant of leukoplakia. Bullous lesions (blisters) are characteristic of immunobullous disorders (like Pemphigus) or infections, but they do not form the clinical spectrum of leukoplakia, which is primarily a keratotic or dysplastic process. **Analysis of Incorrect Options:** * **Homogenous (Option D):** This is the most common type. It presents as a uniform, flat, thin, white plaque with a smooth, wrinkled, or corrugated surface. It carries a lower risk of malignancy. * **Non-Homogenous types:** These carry a higher risk of malignant transformation and include: * **Speckled (Option C):** Also known as Erythroleukoplakia. It consists of white flecks or nodules on an erythematous (red) base. * **Ulcerative (Option A):** Characterized by an ulcerated area within the white patch; this is often a red flag for invasive squamous cell carcinoma. * **Verrucous:** A subtype with a thick, wart-like, irregular surface. **Clinical Pearls for NEET-PG:** * **Most common site:** Buccal mucosa. * **Highest risk of malignancy:** Speckled (Erythroleukoplakia) and Proliferative Verrucous Leukoplakia (PVL). * **Biopsy:** Mandatory to rule out dysplasia or Squamous Cell Carcinoma (SCC). * **Hairy Leukoplakia:** Unlike oral leukoplakia, this is caused by **EBV** in HIV patients and is *not* premalignant.

Q: Facial edema, cheilitis granulomatosa, and a fissured tongue characterize which of the following syndromes?

Melkerson-Rosenthal syndrome. **Explanation:** **Melkersson-Rosenthal Syndrome (MRS)** is a rare neurocutaneous disorder characterized by a classic diagnostic triad. The correct answer is B because the question describes this specific triad: 1. **Recurrent facial edema:** Usually non-pitting and painless, most commonly involving the lips. 2. **Cheilitis granulomatosa:** Chronic swelling of the lip due to granulomatous inflammation (Miescher’s cheilitis is considered a monosymptomatic form of MRS). 3. **Fissured tongue (Lingua plicata):** Present in approximately 30–50% of cases. **Analysis of Incorrect Options:** * **A. Frey's Syndrome (Auriculotemporal Syndrome):** Characterized by localized sweating and flushing in the parotid area while eating (gustatory sweating), usually following parotid surgery or trauma. It does not involve tongue fissuring or granulomatous cheilitis. * **C. Treacher Collins Syndrome:** A genetic disorder of craniofacial development (mandibulofacial dysostosis) presenting with downward-slanting eyes, micrognathia, and malformed ears. It is a structural developmental defect, not an inflammatory/edematous condition. **NEET-PG High-Yield Pearls:** * **The Triad:** Only about 20–25% of patients present with the complete triad simultaneously. * **Facial Nerve Palsy:** Recurrent, lower motor neuron type facial palsy is the third component of the triad (often replacing or accompanying the edema). * **Histopathology:** Skin biopsy of the lip shows **non-caseating granulomas**, similar to sarcoidosis or Crohn’s disease. * **Mnemonic:** Remember **"M-R-S"** — **M**outh (Cheilitis), **R**elapsing paralysis (Facial palsy), **S**plit tongue (Fissured).

Question 1

During tattooing, in which layer of the skin is the pigment/ink primarily deposited?

Accepted Answer

Dermis

Answer

Epidermis

Answer

Subcutaneous tissue

Answer

Muscle and vascular tissue

Question 2

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 3

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 4

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 5

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 6

What is the primary lesion in lichen planus?

Accepted Answer

Papule

Answer

Macule

Answer

Vesicle

Answer

Bullae

Question 7

A 22-year-old female presents with dry papules in the seborrheic areas, especially in the summer. Her father also has a history of similar lesions. What is the most probable diagnosis?

Accepted Answer

Darier's disease

Answer

Pemphigus foliaceus

Answer

Keratosis pilaris

Answer

Seborrheic dermatitis

Question 8

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?

Accepted Answer

Pityriasis rosea

Answer

Pityriasis versicolor

Answer

Pityriasis alba

Answer

Pityriasis rubra pilaris

Question 9

Which of the following is not a type of leukoplakia?

Accepted Answer

Bullous

Answer

Ulcerative

Answer

Speckled

Answer

Homogenous

Question 10

Facial edema, cheilitis granulomatosa, and a fissured tongue characterize which of the following syndromes?

Accepted Answer

Melkerson-Rosenthal syndrome

Answer

Frey's syndrome

Answer

Treacher Collins syndrome

Answer

None of the above

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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