Basic Dermatology Practice Questions

Q: All are true about lichen planus except:

Not associated with oral ulcer. **Explanation:** Lichen Planus (LP) is a chronic inflammatory condition affecting the skin and mucous membranes. The correct answer is **Option A** because Lichen Planus is frequently associated with oral involvement (seen in up to 50% of patients). **Oral Lichen Planus** can present as reticulate (white lacy patterns), atrophic, or **erosive/ulcerative** lesions. Ulcerative oral LP is a well-recognized clinical variant and carries a small risk of malignant transformation into squamous cell carcinoma. **Analysis of other options:** * **Option B: Wickham’s Striae:** These are characteristic fine, white, lacy lines found on the surface of the papules or oral lesions, caused by focal thickening of the granular layer (orthokeratosis). * **Option C: Colloid Bodies:** Also known as **Civatte bodies** or Cytoid bodies, these are found on histology. They represent apoptotic keratinocytes in the lower epidermis/basal layer and are a hallmark of the interface dermatitis seen in LP. * **Option D: 5 'P's:** This is the classic clinical mnemonic for LP: **P**lanar (flat-topped), **P**urple (violaceous), **P**olygonal, **P**ruritic, and **P**apules. **High-Yield Clinical Pearls for NEET-PG:** 1. **Koebner Phenomenon:** Development of lesions along the site of trauma (also seen in Psoriasis and Vitiligo). 2. **Histology Triad:** Hyperkeratosis (without parakeratosis), "Saw-tooth" appearance of rete ridges, and a band-like lymphocytic infiltrate at the dermo-epidermal junction. 3. **Max-Joseph Spaces:** Small areas of separation between the epidermis and dermis due to basal cell degeneration. 4. **Association:** Often associated with **Hepatitis C** infection. 5. **Treatment:** Topical corticosteroids are the first-line treatment.

Q: What is the approximate ratio of keratinocytes to melanocytes in the epidermal melanin unit?

36 keratinocytes : 1 melanocyte. ### Explanation **Concept of the Epidermal Melanin Unit** The correct answer is **D (36 keratinocytes : 1 melanocyte)**. The "Epidermal Melanin Unit" is a functional concept describing the relationship between a single melanocyte and the group of keratinocytes to which it supplies melanin. Melanocytes are dendritic cells located in the **stratum basale**. Through their long cytoplasmic processes (dendrites), they transfer melanosomes to surrounding keratinocytes. In the human epidermis, one melanocyte is functionally associated with approximately **36 keratinocytes**. This ratio ensures uniform pigmentation and protection of keratinocyte nuclei from UV radiation. **Analysis of Options:** * **Option A & C:** These ratios (26:1 and 16:1) are incorrect as they underestimate the extensive dendritic reach of a single melanocyte. * **Option B:** While the math (36:2) simplifies to 18:1, the standard physiological definition specifically identifies a **single** melanocyte as the hub of the unit. * **Option D:** This is the established physiological ratio cited in standard dermatology textbooks (like Fitzpatrick or Rook’s). **High-Yield Clinical Pearls for NEET-PG:** * **Melanocyte Origin:** They are derived from the **Neural Crest** (not the ectoderm). * **Distribution:** While the *number* of melanocytes is roughly the same across all races, the *size, number, and distribution* of melanosomes within the keratinocytes differ. * **Dermal-Epidermal Ratio:** In the basal layer specifically, the ratio of melanocytes to keratinocytes is roughly **1:10**. Do not confuse this "basal ratio" with the "epidermal melanin unit" (1:36). * **Stains:** Melanocytes can be identified using **HMB-45, S-100, or MART-1** immunohistochemistry.

Q: Which of the following statements about geographic tongue is FALSE?

It is a precancerous condition.. **Explanation:** **Geographic Tongue**, also known as **Benign Migratory Glossitis**, is a common, inflammatory, but non-neoplastic condition of the tongue. 1. **Why Option C is the correct answer (False statement):** Geographic tongue is a completely **benign** condition. It has **no malignant potential** and is not considered a precancerous or premalignant lesion. Unlike conditions like oral leukoplakia or erythroplakia, it does not require biopsy or aggressive monitoring for cancer. 2. **Analysis of other options:** * **Option A:** Lesions are characterized by depapillated red patches with a serpiginous white border. These lesions frequently appear in a **bilaterally symmetrical** pattern on the dorsum and lateral borders of the tongue. * **Option B:** Since the condition is asymptomatic in most cases and self-limiting, **no treatment is typically required** other than reassurance. If burning occurs (glossodynia), topical steroids or zinc supplements may be used. * **Option D:** The exact etiology is unknown, but it is strongly associated with **emotional stress**, psoriasis (HLA-Cw6), and atopy. **High-Yield Clinical Pearls for NEET-PG:** * **Pathology:** It involves the loss of **filiform papillae** (atrophy), while fungiform papillae remain. * **Clinical Feature:** The "migratory" nature is key—lesions heal in one area and reappear in another, changing the "map" of the tongue daily. * **Association:** It is often seen in patients with **Psoriasis** and **Fissured Tongue** (Scrotal tongue). * **Histology:** Shows Munro’s microabscesses (neutrophils in the epithelium), similar to psoriasis.

Q: A 30-year-old man with a large appetite is presented with a situation where all cookies at a meeting contain nuts, which others knew he would avoid due to developing blotchy, erythematous, slightly edematous, pruritic plaques on his skin that form and fade within 2 hours. If the man eats the cookies, which of the following sensitized cells would release a mediator that produces these skin lesions?

Mast cell. ### Explanation **Correct Option: B. Mast cell** The clinical presentation describes **Urticaria** (hives). Key diagnostic features include erythematous, edematous, pruritic plaques (wheals) that are transient, typically appearing and resolving within 24 hours (in this case, within 2 hours). Urticaria is a classic example of a **Type I Hypersensitivity reaction** (IgE-mediated). Upon ingestion of an allergen (nuts), IgE antibodies bound to the surface of **sensitized mast cells** cross-link, leading to degranulation. This releases potent inflammatory mediators, primarily **histamine**, which increases vascular permeability and causes vasodilation, resulting in the characteristic dermal edema (wheal) and redness (flare). **Why Incorrect Options are Wrong:** * **A. CD4+ lymphocyte:** These are central to **Type IV (Delayed-type) Hypersensitivity**, such as Allergic Contact Dermatitis. These reactions typically take 48–72 hours to manifest, not 2 hours. * **C. Natural killer cell:** These are part of the innate immune system involved in destroying virally infected or tumor cells; they do not mediate IgE-dependent allergic reactions. * **D. Neutrophil:** While neutrophils may be present in some forms of chronic urticaria or vasculitis, they are not the primary "sensitized" cells responsible for the acute release of mediators in a classic nut allergy. **NEET-PG High-Yield Pearls:** * **Definition of Urticaria:** Transient, itchy, edematous swelling of the dermis that lasts ** 24 hours and leaves staining, consider **Urticarial Vasculitis**. * **Dermatographism:** The most common form of physical urticaria, where linear wheals appear after firm stroking of the skin. * **Treatment of Choice:** Second-generation H1 antihistamines (e.g., Cetirizine, Loratadine). * **Angioedema:** Similar mechanism but involves the deeper dermis and subcutaneous tissue; often associated with ACE inhibitors.

Q: A 45-year-old obese patient presents with hyperpigmented, velvety skin lesions over her neck. What is your diagnosis?

Acanthosis nigricans. ### Explanation **Correct Answer: A. Acanthosis nigricans** **Why it is correct:** Acanthosis nigricans (AN) is a clinical diagnosis characterized by **symmetrical, hyperpigmented, velvety plaques** typically found in intertriginous areas like the **neck (most common)**, axillae, and groin. The "velvety" texture is the hallmark clinical feature, caused by epidermal hypertrophy and papillomatosis. In this patient, the combination of **obesity** and these specific skin changes strongly suggests insulin resistance. Hyperinsulinemia leads to the activation of **IGF-1 receptors** on keratinocytes and fibroblasts, stimulating their proliferation. **Why the other options are incorrect:** * **B. Lichen planus:** Typically presents as the "6 Ps": Purple, Polygonal, Pruritic, Planar, Papules, and Plaques. It often involves the wrists and oral mucosa (Wickham striae), not velvety neck lesions. * **C. Atopic dermatitis:** Characterized by intense pruritus and eczematous lesions (erythema, scaling). In adults, it usually affects flexural surfaces (antecubital/popliteal fossae) and is associated with a personal or family history of allergies. * **D. Contact dermatitis:** An inflammatory reaction to an external allergen or irritant. It presents with acute erythema, vesicles, or chronic scaling localized to the area of contact, rather than generalized velvety hyperpigmentation. **NEET-PG High-Yield Pearls:** * **Associations:** Most commonly associated with **Obesity** and **Type 2 Diabetes Mellitus**. * **Malignancy:** Sudden, severe, or extensive AN (especially involving the palms/soles, known as "Tripe Palms") is a paraneoplastic sign, most commonly associated with **Gastric Adenocarcinoma**. * **Histopathology:** Shows hyperkeratosis and papillomatosis; despite the name, "acanthosis" (thickening of the stratum spinosum) is actually minimal. * **Drug-induced AN:** Can be caused by Nicotinic acid, systemic corticosteroids, and OCPs.

Q: Which of the following statements regarding Erythema nodosum is false?

The lesions are usually non-tender.. ### Explanation **Erythema Nodosum (EN)** is the most common form of **septal panniculitis** (inflammation of the subcutaneous fat). It represents a delayed-type hypersensitivity reaction to various systemic antigens. **Why Option C is the correct answer (False statement):** The hallmark clinical feature of Erythema Nodosum is that the lesions are **exquisitely tender**. Patients typically present with painful, erythematous nodules, most commonly on the pretibial area (shins). The absence of tenderness would point away from a diagnosis of EN. **Analysis of Incorrect Options:** * **Option A:** It is indeed a **hypersensitivity reaction** (Type IV) triggered by various factors including infections, drugs, and systemic diseases. * **Option B:** During the acute phase, the skin overlying the nodules is typically **red, smooth, and shiny**. As the lesion evolves, it may change color to purple or yellowish-brown, resembling a bruise (contusiform appearance). * **Option D:** **Tuberculosis** is a well-known and common cause of EN, especially in the Indian subcontinent. Other common triggers include Streptococcal infections, Sarcoidosis (Lofgren’s syndrome), and Sulfonamides. **High-Yield Clinical Pearls for NEET-PG:** * **Histopathology:** The "Gold Standard" finding is **septal panniculitis** without vasculitis. Look for **Miescher’s radial granulomas** (small nodules of spindle-shaped histiocytes around a central cleft). * **Distribution:** Usually bilateral and symmetrical; predominantly on the **pretibial** surface. * **Healing:** Lesions heal **without scarring** or atrophy (unlike Erythema Induratum/Bazin’s disease, which is a lobular panniculitis that often ulcerates and scars). * **Lofgren’s Syndrome:** A triad of Erythema Nodosum, bilateral hilar lymphadenopathy, and arthralgia (highly suggestive of Sarcoidosis).

Q: Symptomatic dermographism is commonly seen in which of the following conditions?

Chronic urticaria. **Explanation:** **Symptomatic dermographism** (also known as "skin writing") is the most common form of physical urticaria. It occurs when mast cells release histamine in response to physical pressure or shearing forces on the skin, resulting in a linear wheal and flare reaction accompanied by itching. 1. **Why Chronic Urticaria is correct:** Symptomatic dermographism is frequently associated with **Chronic Spontaneous Urticaria (CSU)**. In patients with CSU, the mast cells are in a "primed" or hyper-irritable state due to circulating autoantibodies (like anti-FcεRI) or other inflammatory mediators. This lowers the threshold for mast cell degranulation, making the skin highly reactive to minor physical trauma. 2. **Why other options are incorrect:** * **Acute Urticaria:** This is usually a self-limiting reaction to a specific trigger (food, drug, or infection). While dermographism can occur, it is not a hallmark feature as it is in chronic cases. * **Cholinergic Urticaria:** This is triggered by an increase in core body temperature (exercise, hot showers). It presents with characteristic small (1–3 mm) punctate wheals rather than linear dermographic wheals. * **Urticarial Vasculitis:** This is a type III hypersensitivity reaction involving small vessel inflammation. Lesions are painful rather than itchy, last >24 hours, and leave behind post-inflammatory hyperpigmentation—features not seen in dermographism. **High-Yield Clinical Pearls for NEET-PG:** * **Darier’s Sign:** Pathognomonic for **Mastocytosis**. It is a localized form of dermographism where rubbing a macule/papule results in a wheal. * **White Dermographism:** Seen in **Atopic Dermatitis**. Instead of a red wheal, a white line appears due to paradoxical vasoconstriction. * **Diagnosis:** Symptomatic dermographism is confirmed using a **Dermographometer** (applying a specific pressure of 36 g/mm²).

Q: What is the most common site for hypertrophic keloids?

Presternal area. **Explanation:** The correct answer is **C. Presternal area**. **Understanding the Concept:** Keloids are benign overgrowths of fibrous tissue (collagen) that extend beyond the boundaries of the original wound and do not regress spontaneously. They occur due to an exaggerated healing response. The **presternal area** is the most common site for keloid formation because this region is subject to high skin tension and constant movement during respiration. Other high-risk areas include the upper back, shoulders, and earlobes (often following piercings). **Analysis of Options:** * **A. Face:** While keloids can occur on the face (especially the jawline), it is not the most common site. However, the face is a common site for *hypertrophic scars*, which stay within the wound boundaries. * **B. Leg:** The lower limbs are relatively uncommon sites for keloid formation compared to the trunk and upper extremities. * **D. Arm:** The deltoid region of the arm is a frequent site (often due to vaccinations like BCG), but statistically, the presternal area remains the most frequent location. **Clinical Pearls for NEET-PG:** * **Histology:** Characterized by thick, eosinophilic, "glassy" collagen bundles (Keloidal collagen). * **Risk Factors:** More common in individuals with darker skin (Fitzpatrick types IV-VI) and those with a genetic predisposition. * **Keloid vs. Hypertrophic Scar:** Keloids extend *beyond* the wound margins and rarely regress; hypertrophic scars stay *within* the margins and may regress over time. * **Treatment:** Intralesional Triamcinolone acetonide (corticosteroid) is the first-line treatment. Surgical excision alone has a high recurrence rate and should be combined with adjuvant therapy (e.g., pressure therapy or radiotherapy).

Q: Erythroderma is related with all of the following except?

Lepromatous leprosy. **Explanation:** **Erythroderma** (Exfoliative Dermatitis) is a clinical syndrome characterized by universal or near-universal redness (erythema) and scaling involving more than 90% of the body surface area. **Why Lepromatous Leprosy is the correct answer:** Lepromatous leprosy (LL) typically presents with multiple symmetric macules, papules, nodules, or diffuse infiltration of the skin. While it can cause widespread skin involvement, it **does not** manifest as erythroderma. In contrast, the other options are well-documented triggers for exfoliative dermatitis. **Analysis of other options:** * **Psoriasis:** This is the **most common** pre-existing skin disease to progress to erythroderma (Psoriatic Erythroderma), often triggered by the withdrawal of systemic steroids or irritant topical therapy. * **Air-borne Contact Dermatitis (ABCD):** Chronic, severe allergic contact dermatitis (commonly due to *Parthenium*) can generalize and lead to erythroderma, especially in elderly males. * **Sulfonamides:** Drug hypersensitivity reactions are the second most common cause of erythroderma. Sulfonamides, antiepileptics, and allopurinol are frequent culprits. **High-Yield Clinical Pearls for NEET-PG:** * **Causes of Erythroderma (Mnemonic: SCALP):** **S**eborrheic dermatitis, **C**ontact dermatitis, **A**topic dermatitis, **L**ymphoma (Sezary Syndrome), **P**soriasis/Pityriasis Rubra Pilaris. * **Clinical Sign:** "Nose sign" (sparing of the nose and paranasal area) is often seen in erythroderma due to PRP. * **Complications:** High-output cardiac failure, hypothermia, and protein loss (hypoalbuminemia) due to excessive scaling. * **Histopathology:** Often non-specific; multiple biopsies may be required to identify the underlying primary dermatosis.

Q: All of the following features are present in acrocyanosis except:

Episodic. **Explanation:** **Acrocyanosis** is a functional peripheral vascular disorder characterized by persistent, painless, symmetric cyanosis of the hands, feet, and occasionally the face. **Why "Episodic" is the correct (Except) answer:** Unlike Raynaud’s phenomenon, which is **episodic** and triggered by sudden cold exposure (paroxysmal), acrocyanosis is **persistent**. Once the cyanosis develops, it remains relatively constant, though it may intensify with cold and improve (but not necessarily disappear) with warmth. **Analysis of Incorrect Options:** * **A. Tendency to affect young females:** This is a classic demographic feature. It most commonly presents in adolescent girls and young women (typically 20–30 years of age). * **B. Painless:** Acrocyanosis is characteristically painless. This distinguishes it from other vasospastic conditions like Raynaud’s (which can be painful) or erythromelalgia (which is burning). * **D. Accompanied by chilblains:** Patients with acrocyanosis often have a "cold-sensitive" constitution. It is frequently associated with other cold-induced injuries, most notably **chilblains (pernio)** and hyperhidrosis (sweaty palms/soles). **NEET-PG High-Yield Pearls:** 1. **Clinical Triad:** Persistent cyanosis, coldness of extremities, and local hyperhidrosis. 2. **Trophic Changes:** Unlike Raynaud’s or Buerger’s disease, acrocyanosis **does not** lead to ulceration, gangrene, or trophic skin changes. 3. **Pathophysiology:** Caused by vasospasm of the small cutaneous arteries/arterioles and compensatory dilatation of the post-capillary venules. 4. **Prognosis:** Benign condition; treatment is usually reassurance and cold protection. Calcium channel blockers are rarely needed.

Question 1

All are true about lichen planus except:

Accepted Answer

Not associated with oral ulcer

Answer

Wickham's striae present

Answer

Colloid body on histology

Answer

Morphology can be represented by 5 'P's

Question 2

What is the approximate ratio of keratinocytes to melanocytes in the epidermal melanin unit?

Accepted Answer

36 keratinocytes : 1 melanocyte

Answer

26 keratinocytes : 1 melanocyte

Answer

36 keratinocytes : 2 melanocytes

Answer

16 keratinocytes : 1 melanocyte

Question 3

Which of the following statements about geographic tongue is FALSE?

Accepted Answer

It is a precancerous condition.

Answer

Lesions may be bilaterally symmetrical on the tongue.

Answer

No treatment is typically required.

Answer

It may be related to emotional stress.

Question 4

A 30-year-old man with a large appetite is presented with a situation where all cookies at a meeting contain nuts, which others knew he would avoid due to developing blotchy, erythematous, slightly edematous, pruritic plaques on his skin that form and fade within 2 hours. If the man eats the cookies, which of the following sensitized cells would release a mediator that produces these skin lesions?

Accepted Answer

Mast cell

Answer

CD4+ lymphocyte

Answer

Natural killer cell

Answer

Neutrophil

Question 5

A 45-year-old obese patient presents with hyperpigmented, velvety skin lesions over her neck. What is your diagnosis?

Accepted Answer

Acanthosis nigricans

Answer

Lichen planus

Answer

Atopic dermatitis

Answer

Contact dermatitis

Question 6

Which of the following statements regarding Erythema nodosum is false?

Accepted Answer

The lesions are usually non-tender.

Answer

It is considered a hypersensitivity reaction.

Answer

The skin overlying the lesions is red, smooth, and shiny.

Answer

It can be associated with tuberculosis.

Question 7

Symptomatic dermographism is commonly seen in which of the following conditions?

Accepted Answer

Chronic urticaria

Answer

Acute urticaria

Answer

Cholinergic urticaria

Answer

Urticarial vasculitis

Question 8

What is the most common site for hypertrophic keloids?

Accepted Answer

Presternal area

Answer

Face

Answer

Leg

Answer

Arm

Question 9

Erythroderma is related with all of the following except?

Accepted Answer

Lepromatous leprosy

Answer

Psoriasis

Answer

Air-borne dermatitis

Answer

Sulfonamides

Question 10

All of the following features are present in acrocyanosis except:

Accepted Answer

Episodic

Answer

Tendency to affect young females

Answer

Painless

Answer

Accompanied by chilblains

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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