Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 41: Darier's sign is seen in which of the following conditions?

A. Lichen nitidus
B. Urticaria pigmentosa (Correct Answer)
C. Vitiligo
D. Lichen sclerosus

Explanation: **Explanation:** **Darier’s Sign** is a classic clinical sign in dermatology characterized by the development of a wheal and flare reaction (erythema and edema) within minutes of firm stroking or rubbing of a skin lesion. 1. **Why Urticaria Pigmentosa is correct:** Urticaria pigmentosa is the most common form of **Cutaneous Mastocytosis**. In this condition, there is an abnormal accumulation of mast cells in the dermis. Mechanical stimulation (rubbing) causes these mast cells to degranulate, releasing inflammatory mediators like **histamine**. This leads to localized vasodilation and increased capillary permeability, manifesting as the characteristic wheal (Darier’s sign). 2. **Why other options are incorrect:** * **Lichen nitidus:** Characterized by "pinpoint," shiny, flesh-colored papules. It typically shows the **Koebner phenomenon** (isomorphic response), not Darier’s sign. * **Vitiligo:** An autoimmune depigmenting disorder. It also exhibits the Koebner phenomenon but lacks mast cell involvement. * **Lichen sclerosus:** A chronic inflammatory dermatosis (often genital) characterized by porcelain-white plaques and atrophy. It does not involve mast cell degranulation. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudo-Darier Sign:** A transient rippling or piloerection of the skin after stroking; seen in **Smooth Muscle Hamartoma**. * **Reverse Darier Sign:** Blanching of the lesion after stroking; seen in **Anetoderma**. * **Mastocytosis Triad:** Darier’s sign, flushing, and dermatographism. * **Differential Diagnosis:** While most common in Mastocytosis, Darier’s sign can rarely be seen in Leukemia Cutis or Juvenile Xanthogranuloma.

Question 42: What is the term for a cyst that remains in the jaw after a tooth has been removed?

A. Lateral Periodontal Cyst
B. Radicular Cyst
C. Residual Cyst (Correct Answer)
D. None of the above

Explanation: ### Explanation **Correct Answer: C. Residual Cyst** **The Concept:** A **Residual Cyst** is an inflammatory odontogenic cyst that remains in the jaw after the offending tooth has been extracted. It most commonly develops from a pre-existing **Radicular Cyst** (periapical cyst) that was not properly curetted or removed during the tooth extraction process. Over time, the epithelial remnants continue to proliferate, forming a radiolucent lesion in an edentulous (toothless) area of the alveolar bone. **Analysis of Incorrect Options:** * **A. Lateral Periodontal Cyst:** This is a non-inflammatory developmental cyst located on the lateral aspect of a tooth root. It is associated with a **vital tooth**, whereas a residual cyst occurs in an area where the tooth is missing. * **B. Radicular Cyst:** This is the most common inflammatory cyst of the jaw, found at the apex of a **non-vital tooth**. While a residual cyst originates from a radicular cyst, the term "radicular" specifically implies the cyst is still attached to a tooth root. Once the tooth is removed and the cyst remains, it is renamed a "residual" cyst. **High-Yield Clinical Pearls for NEET-PG:** * **Radiographic Appearance:** Typically appears as a well-defined unilocular radiolucency in an edentulous space. * **Pathogenesis:** Derived from the **Rests of Malassez** (epithelial remnants in the periodontal ligament). * **Treatment:** Surgical enucleation is the treatment of choice. * **Differential Diagnosis:** Always consider **Keratocystic Odontogenic Tumor (KOT)** or **Ameloblastoma** if the lesion shows aggressive features or recurs.

Question 43: Which of the following conditions is typically pruritic?

A. Lichen planus (Correct Answer)
B. Psoriasis
C. Ichthyosis
D. Secondary syphilis

Explanation: **Explanation:** Pruritus (itching) is a hallmark symptom in dermatology, and distinguishing between pruritic and non-pruritic eruptions is a high-yield skill for NEET-PG. **Lichen Planus (Correct Answer):** Lichen planus is classically described by the **"6 Ps"**: Planar (flat-topped), Purple, Polygonal, Pruritic, Papules, and Plaques. The itching in Lichen Planus is typically intense and characteristic. Unlike many other itchy conditions, patients often **rub** the lesions rather than scratch them, which is why excoriation marks are frequently absent despite the severe pruritus. **Why the other options are incorrect:** * **Psoriasis:** While some patients may report mild itching, classic Psoriasis is generally considered **non-pruritic** or minimally symptomatic. The diagnosis relies on the presence of silvery scales and the Auspitz sign rather than the symptom of itch. * **Ichthyosis:** This is a disorder of keratinization characterized by dry, "fish-like" scaly skin. While the dryness (xerosis) can occasionally cause mild discomfort, it is not primarily a pruritic condition. * **Secondary Syphilis:** Known as the "Great Mimicker," its copper-red maculopapular rash (classically involving palms and soles) is characteristically **non-pruritic**. This is a crucial clinical differentiator from other viral or allergic exanthems. **Clinical Pearls for NEET-PG:** * **Wickham Striae:** Fine white reticular patterns seen on the surface of Lichen Planus papules. * **Koebner Phenomenon:** Development of new lesions at sites of trauma; seen in both Lichen Planus and Psoriasis. * **Max Joseph Space:** A histopathological feature of Lichen Planus (subepidermal clefting). * **High-Yield Pruritic Conditions:** Scabies, Lichen Planus, Dermatitis Herpetiformis, and Atopic Dermatitis.

Question 44: Aphthous-like ulcers are seen in which of the following conditions?

A. Behcet syndrome
B. Sweet syndrome
C. PFAPA (periodic fever, aphthous stomatitis, pharyngitis, adenitis)
D. All of the above (Correct Answer)

Explanation: **Explanation:** Aphthous-like ulcers are painful, recurrent oral erosions that clinically resemble common "canker sores" but are often associated with systemic inflammatory or autoimmune conditions. 1. **Behcet Syndrome:** This is a multisystem inflammatory perivasculitis. Recurrent oral aphthous ulcers are the **hallmark and usually the first symptom** (present in >95% of cases). To meet diagnostic criteria, oral ulcers must recur at least three times in a 12-month period, typically accompanied by genital ulcers and uveitis. 2. **Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis):** While characterized by painful erythematous plaques and fever, a subset of patients (especially those with the **hematologic malignancy-associated variant**) develops painful oral aphthous-like ulcerations. 3. **PFAPA Syndrome:** This is a periodic fever syndrome seen in children. As the acronym suggests, **Aphthous stomatitis** is a core clinical feature, occurring alongside pharyngitis and cervical adenitis during febrile episodes. **Why "All of the above" is correct:** All three conditions share a common pathogenesis involving dysregulated cytokine responses (like TNF-alpha), leading to focal mucosal destruction that manifests as aphthous-like ulceration. **High-Yield Clinical Pearls for NEET-PG:** * **MAGIC Syndrome:** A rare condition showing features of both **M**outh **A**nd **G**enital **I**nflammation with **C**hondritis (overlap of Behcet’s and Relapsing Polychondritis). * **Pathergy Test:** Highly specific for Behcet’s and Sweet Syndrome (development of a papule/pustule 24-48 hours after a sterile needle prick). * **Differential Diagnosis:** Always consider Crohn’s disease, Celiac disease, and nutritional deficiencies (B12, Folate, Iron) when evaluating recurrent aphthous-like ulcers.

Question 45: Urticaria pigmentosa is a disorder of which cells?

A. Mast cells (Correct Answer)
B. Neutrophils
C. Eosinophils
D. Lymphocytes

Explanation: **Explanation:** **Urticaria Pigmentosa** is the most common clinical presentation of **cutaneous mastocytosis**. It is characterized by the abnormal accumulation and proliferation of **mast cells** within the dermis. 1. **Why Mast Cells are Correct:** In this condition, mast cells infiltrate the skin, presenting as reddish-brown macules or papules. When these lesions are stroked or rubbed, the mast cells degranulate, releasing inflammatory mediators like **histamine**. This leads to localized edema and erythema, a pathognomonic clinical sign known as **Darier’s Sign**. 2. **Why other options are incorrect:** * **Neutrophils:** These are primary cells in acute bacterial infections and "Sweet Syndrome" (Acute Febrile Neutrophilic Dermatosis), not mastocytosis. * **Eosinophils:** While often seen in allergic reactions and "Incontinentia Pigmenti" (Stage I), they are not the primary proliferating cell in Urticaria Pigmentosa. * **Lymphocytes:** These are the hallmark of chronic inflammatory conditions and T-cell lymphomas (like Mycosis Fungoides), but they do not characterize mastocytosis. **High-Yield Clinical Pearls for NEET-PG:** * **Darier’s Sign:** Pathognomonic sign where rubbing a lesion causes wheal formation. * **Histopathology:** Shows a "fried-egg" appearance of mast cells. Special stains used include **Toluidine Blue** (shows metachromatic granules), **Giemsa stain**, and **Astra Blue**. * **Immunohistochemistry:** Mast cells are positive for **CD117 (c-kit)** and **Tryptase**. * **Systemic Involvement:** While Urticaria Pigmentosa is usually cutaneous, always check for systemic mastocytosis by measuring **Serum Tryptase** levels.

Question 46: Which of the following is the main etiological factor for Hidradenitis suppurativa?

A. Smoking (Correct Answer)
B. Diabetes
C. Steroid use
D. Obesity

Explanation: **Explanation:** **Hidradenitis Suppurativa (HS)**, also known as Acne Inversa, is a chronic inflammatory skin condition characterized by painful nodules, abscesses, and sinus tracts in intertriginous areas (axilla, groin, inframammary). **Why Smoking is the Correct Answer:** Smoking is considered the most significant **modifiable etiological and triggering factor** for HS. Nicotine and other tobacco components promote follicular occlusion by stimulating keratinocyte hyperproliferation. Furthermore, smoking alters the local immune response and increases the production of pro-inflammatory cytokines (like TNF-α), which drives the characteristic chronic inflammation. Up to 70–90% of patients with HS are active smokers. **Analysis of Incorrect Options:** * **Obesity (Option D):** While obesity is a major risk factor and exacerbating factor (due to mechanical friction, sweat retention, and systemic inflammation), smoking is statistically more strongly linked to the *initiation* and severity of the disease in most epidemiological studies. * **Diabetes (Option B):** HS is associated with metabolic syndrome, but diabetes itself is not a primary etiological driver. It is more often a comorbidity rather than a direct cause. * **Steroid Use (Option C):** Systemic steroids are actually sometimes used to *treat* acute flares of HS. They do not cause the condition, though long-term use can lead to steroid-induced acne, which is a different clinical entity. **High-Yield Clinical Pearls for NEET-PG:** * **Pathogenesis:** The primary event is **follicular occlusion** of the folliculopilosebaceous unit (not the sweat glands, despite the name). * **Classification:** The **Hurley Staging System** is used to grade severity (Stage I: Abscess without tracts; Stage II: Recurrent abscesses with sinus tracts; Stage III: Diffuse involvement/interconnecting tracts). * **Treatment:** Weight loss and **smoking cessation** are the first-line lifestyle modifications. Medical treatment includes topical Clindamycin, oral Tetracyclines, and the TNF-α inhibitor **Adalimumab** (FDA-approved for HS).

Question 47: Microcherry appearance is a characteristic of which of the following conditions?

A. Haemangioma (Correct Answer)
B. Erythema multiforme
C. Lichen planus
D. All of the above

Explanation: **Explanation:** The correct answer is **Haemangioma (Option A)**. The term **"Microcherry appearance"** is a specific dermoscopic finding associated with **Cherry Haemangiomas** (also known as Campbell de Morgan spots) and certain infantile haemangiomas. Under a dermoscope, these lesions appear as multiple, well-demarcated, round-to-oval red, purple, or blue-black structures known as **lacunae** or "clods." These lacunae represent dilated vascular spaces in the papillary dermis, giving the characteristic "microcherry" look. **Why other options are incorrect:** * **Erythema Multiforme (Option B):** This condition is characterized by "Target" or "Iris" lesions. Dermoscopy typically shows a structureless red center with a pale intermediate ring and an erythematous periphery, but not microcherries. * **Lichen Planus (Option C):** The hallmark finding in Lichen Planus is **Wickham Striae** (white reticular lines). Dermoscopically, one would see pearly white structures and "dotted" or "linear" vessels at the periphery, but not vascular lacunae. **High-Yield Clinical Pearls for NEET-PG:** * **Cherry Haemangioma:** The most common vascular proliferation; they increase in number with age and do not regress spontaneously. * **Dermoscopic "Red Lagoon" Sign:** Another term used for the lacunar structures seen in hemangiomas. * **Differential Diagnosis:** If a "microcherry" or lacunar pattern is absent and replaced by a "blue-black" structureless area, one must rule out **Nodular Melanoma**. * **Strawberry Haemangioma:** A type of capillary haemangioma seen in infants that typically undergoes spontaneous involution (unlike cherry haemangiomas).

Question 48: Which among the following is NOT a primary skin lesion?

A. Plaque
B. Macule
C. Abscess (Correct Answer)
D. None of the above

Explanation: ### Explanation In dermatology, skin lesions are categorized into **Primary** (arising de novo as a direct result of the disease process) and **Secondary** (evolving from primary lesions due to evolution, trauma, or infection). **Why Abscess is the Correct Answer:** An **Abscess** is defined as a localized collection of pus in the dermis or subcutaneous tissue. In most dermatological classifications (including standard textbooks like Fitzpatrick or Rook), it is considered a **secondary or special lesion** rather than a primary one. While it may appear "new," it is pathologically an inflammatory evolution often resulting from the progression of a nodule or pustule. **Analysis of Incorrect Options:** * **Plaque:** This is a **Primary Lesion**. It is a palpable, flat-topped, plateau-like elevation greater than 1 cm in diameter (e.g., Psoriasis). * **Macule:** This is a **Primary Lesion**. It is a flat, non-palpable area of color change less than 1 cm in diameter (e.g., Freckles, Vitiligo). **High-Yield Clinical Pearls for NEET-PG:** * **Primary Lesions:** Macule, Papule (<1cm), Patch, Plaque (>1cm), Nodule, Vesicle (<1cm), Bulla (>1cm), Pustule, and Wheal. * **Secondary Lesions:** Scale, Crust, Erosion, Ulcer, Fissure, Atrophy, Scar, and Lichenification. * **The "1 cm Rule":** Most primary lesions use 1 cm as the cutoff between small (macule/papule/vesicle) and large (patch/plaque/bulla) variants. * **Lichenification:** A classic secondary lesion characterized by thickening of the epidermis with exaggerated skin markings, usually due to chronic rubbing.

Question 49: What is Quincke's disease popularly known as?

A. Norwegian scabies
B. Angioneurotic edema (Correct Answer)
C. Seborrhea oleosa
D. Saddle nose

Explanation: **Explanation:** **Quincke’s disease** is the eponym for **Angioneurotic edema** (or simply Angioedema). It was first described by Heinrich Quincke in 1882. **Why Option B is Correct:** Angioedema is a localized, self-limiting swelling of the deeper layers of the skin (dermis and subcutaneous tissue) or mucosal tissues. Unlike urticaria, which affects the superficial dermis, Quincke’s disease involves deeper vascular leakage. It most commonly affects the lips, eyelids, tongue, and larynx. The underlying mechanism involves increased vascular permeability mediated by histamine (allergic) or bradykinin (as seen in Hereditary Angioedema or ACE-inhibitor use). **Why Other Options are Incorrect:** * **A. Norwegian scabies:** Also known as **Crusted scabies**, this is a severe infestation by *Sarcoptes scabiei* seen in immunocompromised patients, characterized by thick, hyperkeratotic crusts containing millions of mites. * **C. Seborrhea oleosa:** This refers to excessive oiliness of the skin due to overactive sebaceous glands, often associated with Seborrheic dermatitis. * **D. Saddle nose:** This is a physical deformity characterized by a collapse of the nasal bridge. It is a classic sign of **Congenital Syphilis**, Lepromatous Leprosy, or Granulomatosis with polyangiitis (Wegener's). **Clinical Pearls for NEET-PG:** * **Quincke’s Sign:** Do not confuse Quincke’s disease with Quincke’s sign (capillary pulsations in the nail bed seen in Aortic Regurgitation). * **Hereditary Angioedema (HAE):** Caused by **C1 esterase inhibitor deficiency**. It is characterized by recurrent angioedema without urticaria or pruritus. * **Emergency Management:** The most dreaded complication of Quincke’s disease is **laryngeal edema**, which can lead to fatal airway obstruction.

Question 50: Blaschko's lines are present along the lines of what?

A. Nerves
B. Lymphatics
C. Vessels
D. Development (Correct Answer)

Explanation: **Explanation:** **Blaschko’s lines** represent a fundamental concept in clinical dermatology. They are non-random cutaneous patterns that do not correspond to any known anatomical structures like nerves, vessels, or lymphatics. **Why "Development" is correct:** Blaschko’s lines represent the **pathways of migration and clonal proliferation of epidermal cells** (keratinocytes and melanocytes) during embryonic development. They reflect the dorso-ventral migration of cells from the neural crest. When a genetic mutation occurs in a single cell during early embryogenesis (a phenomenon known as **cutaneous mosaicism**), the progeny of that cell follow these lines, making the skin disorder visible in a "Blaschkoid" distribution. **Why other options are incorrect:** * **Nerves:** Patterns following nerves are called **Dermatomes** (e.g., Herpes Zoster). Blaschko’s lines are much more curvilinear and do not respect sensory nerve distributions. * **Lymphatics/Vessels:** Patterns following these systems usually present as linear or branching streaks (e.g., Lymphangitis or Vasculitis) and do not form the characteristic "V" or "S" shapes seen in Blaschko’s lines. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** They typically appear as **'V' shapes** on the upper back, **'S' shapes** on the abdomen/lateral trunk, and **linear** patterns on the limbs. * **Common Blaschkoid Conditions:** 1. **Incontinentia Pigmenti** (Classic X-linked dominant example) 2. **Linear Epidermal Nevus** 3. **Hypomelanosis of Ito** 4. **Lichen Striatus** 5. **Linear Psoriasis** * **Key Distinction:** Unlike dermatomes, Blaschko’s lines **do not** stop abruptly at the midline in the same way, though they often respect it.

Practice by Chapter

Structure and Function of Skin

Practice Questions

Cutaneous Histopathology

Practice Questions

Dermatological Examination

Practice Questions

Skin Lesions: Morphology and Description

Practice Questions

Principles of Diagnosis in Dermatology

Practice Questions

Dermatological Procedures

Practice Questions

Wound Healing

Practice Questions

Cutaneous Immunology

Practice Questions

Genetics in Dermatology

Practice Questions

Cutaneous Manifestations of Systemic Diseases

Practice Questions

Geriatric Dermatology

Practice Questions

Pediatric Dermatology Basics

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free