Basic Dermatology Practice Questions

Q: Lesions of pityriasis rosea are distributed mostly on which part of the body?

Trunk. ### Explanation **Pityriasis Rosea (PR)** is a common, self-limiting inflammatory skin disorder characterized by a specific clinical progression and distribution. **Why the Trunk is Correct:** The hallmark of Pityriasis Rosea is its distribution in the **"Christmas Tree" (or fir tree) pattern**. The lesions are primarily located on the **trunk** and proximal limbs. They follow the lines of cleavage (Langer’s lines), creating a symmetrical, V-shaped distribution on the upper back and a horizontal distribution on the lower back. The eruption typically begins with a single, large **"Herald Patch"** (usually on the trunk), followed days later by smaller, oval, erythematous scaly plaques with a characteristic **collarette of scale**. **Analysis of Incorrect Options:** * **A. Face:** PR is known for "sparing" the face in its classic form. Involvement of the face is rare and usually only seen in the "inverse" variant or in pediatric cases. * **C. Scalp:** Similar to the face, the scalp is typically spared. Scalp involvement is more characteristic of Psoriasis or Seborrheic Dermatitis. * **D. Palms and Soles:** These areas are characteristically spared in PR. This is a crucial diagnostic differentiator from **Secondary Syphilis**, which presents with similar scaly lesions but *includes* the palms and soles. **High-Yield Clinical Pearls for NEET-PG:** * **Etiology:** Associated with **HHV-6 and HHV-7** reactivation. * **Herald Patch:** The initial lesion; larger (2–6 cm), salmon-colored, and heralds the generalized eruption. * **Collarette Scale:** The scale is attached at the periphery and free toward the center. * **Hanging Curtain Sign:** When the skin is stretched across the long axis of the lesion, the scales fold like a curtain. * **Differential Diagnosis:** Always rule out Secondary Syphilis (perform VDRL/RPR if palms/soles are involved).

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

Urticaria pigmentosa. **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.

Q: Which condition is characterized by 'Iris lesions'?

Erythema Multiforme. **Explanation:** **Erythema Multiforme (EM)** is the classic condition associated with **Iris lesions**, also known as **Target lesions** or **Bull’s eye lesions**. These are pathognomonic and typically consist of three concentric zones: 1. **Central zone:** Dusky, dark red, or purpuric (sometimes with a central blister). 2. **Middle zone:** A pale, edematous ring. 3. **Outer zone:** A bright red erythematous halo. This morphology results from a cell-mediated (Type IV) hypersensitivity reaction, most commonly triggered by **Herpes Simplex Virus (HSV)** or certain medications. **Analysis of Incorrect Options:** * **SLE (A):** Characterized by a **Malar (Butterfly) rash**—an erythematous, confluent rash over the cheeks and bridge of the nose, sparing the nasolabial folds. * **Aphthous ulcers (C):** These are painful, shallow oral ulcers with a yellow-gray base and an erythematous border, but they do not manifest as targetoid cutaneous lesions. * **DLE (D):** Characterized by well-defined, scaly, erythematous plaques that lead to **atrophy, scarring, and telangiectasia**, often found in sun-exposed areas. **NEET-PG High-Yield Pearls:** * **Most common trigger for EM:** Herpes Simplex Virus (HSV-1 and HSV-2). * **Distribution:** Lesions are typically **acral** (hands and feet) and symmetrical. * **Nikolsky Sign:** Negative in Erythema Multiforme (unlike Pemphigus Vulgaris or SJS/TEN). * **EM Major vs. Minor:** EM Major involves significant mucosal involvement (at least two sites), whereas EM Minor involves minimal or no mucosal involvement.

Q: A 60-year-old diabetic female presents with a burning sensation related to spicy food. Intraoral examination reveals multiple periodontal abscesses and a keratotic area in a lace pattern with occasional erosive areas within the lace pattern. What is the provisional diagnosis for this patient?

Oral lichen planus. ### Explanation **Correct Answer: B. Oral lichen planus** The clinical presentation is classic for **Oral Lichen Planus (OLP)**. The "lace pattern" described is the pathognomonic **Wickham striae**—a network of white, keratotic lines. OLP commonly presents in two forms: the asymptomatic reticular type (lace-like) and the symptomatic **erosive type**, which causes the burning sensation triggered by spicy food. The presence of periodontal abscesses and diabetes in this patient suggests a possible association with **Grinspan’s Syndrome** (a triad of Hypertension, Diabetes Mellitus, and Oral Lichen Planus). **Why other options are incorrect:** * **Oral hairy leukoplakia:** Typically seen in HIV/immunocompromised patients, it presents as non-scrapable white corrugated patches on the **lateral borders** of the tongue, not as a generalized lace-like pattern. * **Oral squamous cell carcinoma:** Usually presents as a chronic non-healing ulcer with indurated borders or a persistent exophytic growth. While OLP has a small risk of malignant transformation, the "lace pattern" specifically points to a lichenoid etiology. * **Oral pemphigus:** Characterized by fragile vesicles that rupture to leave painful, ragged erosions. It lacks the characteristic hyperkeratotic Wickham striae. **NEET-PG High-Yield Pearls:** * **Wickham Striae:** White lacy lines due to focal hypergranulosis. * **Histopathology:** Shows "saw-tooth" rete ridges, liquefaction degeneration of the basal layer, and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Civatte Bodies:** Apoptotic keratinocytes found in the lower epidermis/upper dermis. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo).

Q: Which of the following is FALSE about erythema nodosum?

The trunk is the most common site for these lesions.. **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 stimuli. **1. Why Option A is False (The Correct Answer):** The **shins (pretibial area)** are the most common site for erythema nodosum, not the trunk. The lesions are typically symmetrical, tender, erythematous nodules located on the lower extremities. While they can occasionally appear on the forearms or thighs, truncal involvement is extremely rare. **2. Analysis of Other Options:** * **Option B:** The lesions undergo a characteristic color change. They begin as bright red, tense nodules and, as they resolve over 2–6 weeks, they evolve into a **bruise-like appearance** (changing from blue/purple to yellowish-green). This is known as *erythema contusiformis*. * **Option C:** Sarcoidosis is a well-known cause of EN. When EN is associated with bilateral hilar lymphadenopathy, fever, and arthralgia, it is termed **Löfgren’s syndrome**, which carries a good prognosis. * **Option D:** The lesions are classically **exquisitely tender and painful** to touch, which is a hallmark clinical feature helping to differentiate it from other dermatological nodules. **High-Yield Clinical Pearls for NEET-PG:** * **Histopathology:** Shows **septal panniculitis** without vasculitis. Look for **Miescher’s radial granulomas** (small nodules of spindle-shaped cells around a central cleft). * **Etiology Mnemonic (SHOUT):** **S**arcoidosis, **H**istoplasmosis (and other fungi), **O**CPs/Pregnancy, **U**lcerative colitis (IBD), **T**uberculosis/Streptococcal infections (most common trigger in children). * **Management:** Usually self-limiting; treated with NSAIDs, bed rest, and treating the underlying cause.

Q: Keratoderma is/are seen in?

Pityriasis rubra pilaris. **Explanation:** **Keratoderma** refers to the marked thickening of the stratum corneum (hyperkeratosis) on the palms and soles. **Why Pityriasis Rubra Pilaris (PRP) is correct:** PRP is a chronic inflammatory dermatosis characterized by the "red-orange" triad. One of its hallmark features is **diffuse, orange-red palmoplantar keratoderma**. Other diagnostic features include follicular papules on an erythematous base (nut-meg grater sensation), "islands of sparing" (normal skin amidst affected areas), and progression to erythroderma. **Why other options are incorrect:** * **Pemphigus:** This is a group of autoimmune blistering diseases (Type II hypersensitivity) characterized by acantholysis (loss of cell-to-cell adhesion) and intraepidermal blisters. It does not typically present with hyperkeratotic thickening. * **Pityriasis Rosea:** A self-limiting inflammatory condition characterized by a "herald patch" followed by a "Christmas tree" distribution of scaly papules and plaques. It involves fine scaling (collarette scale) rather than keratoderma. * **Dermatitis Herpetiformis:** An intensely pruritic, autoimmune blistering disorder associated with Celiac disease. It presents with grouped (herpetiform) vesicles on extensor surfaces, not keratoderma. **High-Yield Clinical Pearls for NEET-PG:** * **PRP Triad:** Follicular plugging, orange-red keratoderma, and islands of sparing. * **Differential for Palmoplantar Keratoderma:** Psoriasis, PRP, Eczema (Tylotic), Tinea pedis, and hereditary syndromes (e.g., Papillon-Lefèvre syndrome). * **Treatment of choice for PRP:** Oral Retinoids (Acitretin) are the first-line systemic therapy.

Q: What is the most appropriate management for recurrent keloids?

Intramarginal excision followed by radiation. **Explanation:** The management of **recurrent keloids** is challenging because simple surgical excision has an exceptionally high recurrence rate (up to 45–100%). **Why Option B is Correct:** The gold standard for recurrent or recalcitrant keloids is **Intramarginal (intralesional) excision** followed by adjuvant therapy, most commonly **Radiotherapy**. * **Intramarginal Excision:** Unlike traditional surgery, the incision is made *within* the keloid margin, leaving a small rim of keloid tissue. This avoids triggering a new inflammatory response in the surrounding healthy dermis. * **Radiation:** Post-operative radiotherapy (usually started within 24–48 hours) inhibits fibroblast proliferation and collagen synthesis, significantly reducing the risk of recurrence to less than 10–20%. **Why Other Options are Incorrect:** * **A. Excisional Surgery:** Simple extramarginal excision often leads to larger recurrences due to the stimulation of new collagen at the wound edges. * **C. Cryosurgery:** While useful for very small, early keloids (by causing vascular stasis and necrosis), it is rarely effective as a monotherapy for large or recurrent lesions. * **D. Silicone Gel Sheeting:** This is a non-invasive prophylactic measure or an adjunct treatment. It is insufficient as a primary treatment for established recurrent keloids. **NEET-PG High-Yield Pearls:** * **First-line treatment** for most keloids: **Intralesional Triamcinolone Acetate (TAC)** (10–40 mg/ml). * **Keloids vs. Hypertrophic Scars:** Keloids extend *beyond* the original wound boundaries and do not regress spontaneously; hypertrophic scars stay *within* the boundaries and may regress. * **Common Site:** Presternal area, deltoid, and earlobes. * **Earlobes:** Often treated with "Pressure Earrings" post-excision to prevent recurrence.

Question 1

Lesions of pityriasis rosea are distributed mostly on which part of the body?

Accepted Answer

Trunk

Answer

Face

Answer

Scalp

Answer

Palms and soles

Question 2

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

Accepted Answer

Urticaria pigmentosa

Answer

Lichen nitidus

Answer

Vitiligo

Answer

Lichen sclerosus

Question 3

Which condition is characterized by 'Iris lesions'?

Accepted Answer

Erythema Multiforme

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Aphthous ulcers

Answer

Discoid Lupus Erythematosus (DLE)

Question 4

A 60-year-old diabetic female presents with a burning sensation related to spicy food. Intraoral examination reveals multiple periodontal abscesses and a keratotic area in a lace pattern with occasional erosive areas within the lace pattern. What is the provisional diagnosis for this patient?

Accepted Answer

Oral lichen planus

Answer

Oral hairy leukoplakia

Answer

Oral squamous cell carcinoma

Answer

Oral pemphigus

Question 5

Which of the following is FALSE about erythema nodosum?

Accepted Answer

The trunk is the most common site for these lesions.

Answer

The initial lesion is red and later turns blue.

Answer

It can occur in Sarcoidosis.

Answer

The lesions are painful.

Question 6

Keratoderma is/are seen in?

Accepted Answer

Pityriasis rubra pilaris

Answer

Pemphigus

Answer

Pityriasis rosea

Answer

Dermatitis herpetiformis

Question 7

A 15-year-old healthy boy presents with pruritic, erythematous, blocky skin lesions on his arms, legs, and trunk that appear within an hour of consuming seafood. What is the most likely diagnosis?

Accepted Answer

Localized anaphylaxis

Answer

Localized immune-complex deposition

Answer

Cell-mediated hypersensitivity

Answer

Release of complement C3b

Question 8

Perioral and periorbital skin lesions are seen in which condition?

Accepted Answer

Primary systemic amyloidosis (pinch purpura)

Answer

Idiopathic thrombocytopenic purpura

Answer

Cutaneous vasculitis

Answer

Lupus erythematosus

Question 9

What is the most appropriate management for recurrent keloids?

Accepted Answer

Intramarginal excision followed by radiation

Answer

Excisional surgery

Answer

Cryosurgery

Answer

Silicone gel sheeting

Question 10

Which of the following is NOT a feature of dyskeratosis?

Accepted Answer

Most common congenital syndrome involving nails

Answer

Premalignant leukoplakia

Answer

Atrophy and telangiectasia

Answer

Hypopigmented macules

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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