Basic Dermatology Practice Questions

Q: Lines of Blaschko represent:

Lines of development. **Explanation:** **Lines of Blaschko** are non-random cutaneous patterns that do not correspond to any known vascular, lymphatic, or nervous pathways. Instead, they represent the **lines of migration and proliferation of epidermal cells** (keratinocytes and melanocytes) during embryonic development. 1. **Why Option D is Correct:** During embryogenesis, precursor cells migrate from the neural crest and proliferate to cover the body surface. These lines reflect the clonal expansion of these cells. They typically follow a "V-shape" on the back, an "S-shape" on the chest and abdomen, and a linear pattern on the limbs. They become visible only in certain genetic or acquired skin diseases (e.g., Incontinentia Pigmenti, Linear Epidermal Nevus) where a mutation occurs in a subset of cells (mosaicism). 2. **Why Other Options are Incorrect:** * **A & B (Lymphatics/Blood vessels):** Vascular and lymphatic distributions follow distinct anatomical branching patterns (e.g., angiosomes) which do not match the characteristic whorled or V-shaped patterns of Blaschko lines. * **C (Nerves):** Lines following nerve distributions are called **Dermatomes**. While dermatomes are also developmental, they represent the sensory distribution of spinal nerves and differ significantly in morphology from Blaschko lines. **High-Yield Clinical Pearls for NEET-PG:** * **Langer’s Lines:** Lines of skin tension/cleavage (collagen orientation); crucial for surgical incisions to minimize scarring. * **Kraissl’s Lines:** Lines of maximum skin tension in a living, moving body (often used interchangeably with Langer's in clinical practice). * **Mosaicism:** The most common reason Blaschko lines become clinically apparent. * **Key Disease Example:** *Incontinentia Pigmenti* classically follows the Lines of Blaschko.

Q: In erythema migrans, which papillae of the tongue are absent?

Filiform. **Explanation:** **Erythema migrans**, commonly known as **Geographic Tongue**, is a benign inflammatory condition characterized by the loss of specific lingual papillae. **Why Filiform is the correct answer:** The characteristic "map-like" appearance of geographic tongue is caused by the **atrophy or loss of filiform papillae**. These are the most numerous papillae on the tongue and are responsible for its normal velvety, grayish-pink texture. In erythema migrans, focal areas of de-papillation occur, resulting in smooth, red patches (erythema) surrounded by a raised, white, keratotic border. These patches "migrate" over time as the filiform papillae heal in one area and undergo atrophy in another. **Why the other options are incorrect:** * **Fungiform Papillae:** These are mushroom-shaped and contain taste buds. In geographic tongue, they often remain intact and appear as prominent red dots within the denuded areas of filiform atrophy. * **Foliate Papillae:** These are located on the lateral borders of the posterior tongue. While they can be involved in other inflammatory conditions, they are not the primary papillae lost in erythema migrans. * **Circumvallate Papillae:** These are large, circular papillae arranged in a V-shape at the back of the tongue. They are structural landmarks and are not affected by the migratory desquamation seen in this condition. **High-Yield NEET-PG Pearls:** * **Histology:** Shows "Munro’s microabscesses" (neutrophils in the epithelium), similar to psoriasis. * **Associations:** Often associated with **Fissured Tongue** (Scrotal tongue) and sometimes linked to Psoriasis or Vitamin B deficiency. * **Clinical Feature:** Usually asymptomatic, but may cause a burning sensation with spicy or acidic foods. * **Treatment:** Reassurance is key; topical steroids or zinc supplements may be used in symptomatic cases.

Q: A 35-year-old woman develops an itchy rash over her back, legs, and trunk several hours after swimming in a lake. Erythematous, edematous papules are noted. The wheals vary in size. There are no mucosal lesions and no swelling of the lips. What is the most likely diagnosis?

Urticaria. ### Explanation **Correct Answer: A. Urticaria** The clinical presentation of **erythematous, edematous papules (wheals)** that appear rapidly (within hours) and are intensely itchy is classic for **Urticaria**. In this scenario, the trigger is likely **Aquagenic Urticaria** or **Cold Urticaria** (due to lake water temperature). **Medical Concept:** Urticaria is a Type I Hypersensitivity reaction (IgE-mediated) or a physical trigger leading to mast cell degranulation. This releases histamine, causing vasodilation and localized dermal edema (the wheal). The absence of mucosal involvement and lip swelling helps rule out systemic anaphylaxis or angioedema. --- ### Why the other options are incorrect: * **B. Folliculitis:** This presents as small, dome-shaped pustules or erythematous papules centered around hair follicles. It is usually painful or tender rather than intensely pruritic and does not present as transient wheals. * **C. Erythema Multiforme (EM):** EM is characterized by "target" or "iris" lesions (concentric rings). It is often associated with infections (HSV) or drugs and typically involves the acral surfaces (palms/soles) and sometimes mucosa. * **D. Erythema Chronicum Migrans:** This is the hallmark of early **Lyme Disease**. It presents as a single, slowly expanding "bull's-eye" rash (annular erythema) at the site of a tick bite, not as multiple, itchy, edematous wheals. --- ### NEET-PG High-Yield Pearls: * **Definition of a Wheal:** A transient, elevated lesion caused by local dermal edema that typically disappears within 24 hours without leaving a scar. * **Dermographism:** The most common form of physical urticaria, where linear wheals appear after stroking the skin. * **Treatment of Choice:** Second-generation non-sedating H1 antihistamines (e.g., Cetirizine, Loratadine). * **Histopathology:** Shows superficial dermal edema with dilated blood vessels and a perivascular infiltrate of neutrophils and eosinophils.

Q: What is the characteristic finding of a beaded margin of the eyelid?

Lipoid proteinosis. ### Explanation **Correct Answer: D. Lipoid Proteinosis** **Lipoid proteinosis** (also known as Urbach-Wiethe disease) is a rare autosomal recessive disorder caused by mutations in the **ECM1 gene**. This leads to the deposition of hyaline-like material in the skin, mucosa, and internal organs. * **The "Beaded Margin":** The pathognomonic clinical finding is **moniliform blepharosis**, which refers to rows of small, pearly, waxy papules along the eyelid margins. These papules create a "beaded" appearance and are a classic high-yield finding for NEET-PG. * **Other Key Features:** Patients often present with early-childhood **hoarseness of voice** (due to laryngeal infiltration) and a thickened, "woody" tongue with a shortened frenulum. **Why the other options are incorrect:** * **A & C. Granuloma Annulare (GA):** GA typically presents as annular (ring-shaped) plaques with a border of firm, skin-colored to erythematous papules. While it has a "beaded" border in a circular configuration, it classically affects the dorsal hands and feet, not the eyelid margins. * **B. Leprosy:** Ocular involvement in leprosy (especially Lepromatous) includes madarosis (loss of eyebrows/eyelashes), lagophthalmos, and corneal anesthesia, but it does not present with a beaded eyelid margin. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Look for bilateral, **comma-shaped (bean-shaped) calcifications** in the temporal lobes/hippocampus on a CT scan. * **Histopathology:** Periodic Acid-Schiff **(PAS) positive**, diastase-resistant hyaline material is deposited around blood vessels and sweat glands. * **Inheritance:** Autosomal Recessive (ECM1 gene on chromosome 1q21). * **Triad to Remember:** Hoarseness + Moniliform blepharosis + Temporal lobe calcification.

Q: Multipleround to oval erythematous patches with fine central scale distributed along the skin tension lines on the trunk is highly suggestive of?

Pityriasis rosea. ### Explanation The clinical description provided is a classic presentation of **Pityriasis Rosea (PR)**. **Why Pityriasis Rosea is correct:** Pityriasis rosea is a self-limiting, inflammatory skin condition (likely viral, associated with HHV-6/7). It typically begins with a single, large **"Herald Patch"** followed by a generalized eruption of smaller, oval, erythematous macules and patches. These lesions feature a characteristic **"collarette" of fine scales** (central clearing with peripheral scaling). Crucially, the long axes of these oval lesions follow the **skin tension lines (Langer’s lines)**, creating the pathognomonic **"Christmas Tree" or "Fir Tree" distribution** on the trunk. **Why the other options are incorrect:** * **Tinea versicolor:** Presents as hypo- or hyperpigmented macules with fine "branny" scales (furfuraceous). While it occurs on the trunk, it does not follow Langer’s lines and is caused by *Malassezia* species. * **Lichen planus:** Characterized by the "6 Ps": Pruritic, Purple, Polygonal, Planar, Papules, and Plaques. It typically involves the flexor surfaces of wrists and shins and features **Wickham striae**, not oval patches along tension lines. * **Seborrheic dermatitis:** Presents as greasy, yellowish scales on an erythematous base. It is localized to "seborrheic areas" (scalp, eyebrows, nasolabial folds, and presternal area) rather than a generalized distribution along tension lines. **High-Yield Clinical Pearls for NEET-PG:** * **Herald Patch:** The initial lesion, seen in 80% of cases; larger than subsequent lesions. * **Collarette Scale:** The scale is attached peripherally and free centrally. * **Hanging Curtain Sign:** When the skin is pinched, the scales fold inward (characteristic of PR). * **Treatment:** Usually self-limiting (6–8 weeks). Reassurance is key; antihistamines or topical steroids can be used for pruritus.

Q: A child presents with a lesion on the buttocks that has been present for 2 years, spreading peripherally with central scarring and is asymptomatic. What is the most likely diagnosis?

Erythema annulare centrifugum. **Explanation:** The clinical presentation of a long-standing (2 years), slow-growing, annular lesion with **peripheral spread and central clearing/scarring** is characteristic of **Erythema Annulare Centrifugum (EAC)**. 1. **Why EAC is correct:** EAC is a reactive skin condition (often triggered by infections, drugs, or malignancies) characterized by erythematous, ring-shaped lesions. The "centrifugal" spread means it expands outward while the center heals. The chronic duration (years) and asymptomatic nature are hallmark features that distinguish it from acute inflammatory rashes. 2. **Why other options are incorrect:** * **Erythema Migrans:** This is the pathognomonic rash of **Lyme disease** (Borrelia burgdorferi). It expands rapidly over days to weeks (not years) and is typically associated with systemic symptoms like fever and lymphadenopathy. * **Erythema Marginatum:** This is a major Jones criterion for **Acute Rheumatic Fever**. It is a transient, evanescent (comes and goes quickly), pink, non-pruritic rash. It would not persist for 2 years. * **Erythema Gyratum Repens:** This is a paraneoplastic syndrome (often associated with lung cancer) characterized by a "wood-grain" appearance. It moves very rapidly (up to 1 cm per day), unlike the slow progression described here. **High-Yield Clinical Pearls for NEET-PG:** * **EAC "Trailing Scale":** A classic diagnostic sign of the superficial variant of EAC is a thin white scale just inside the advancing edge. * **Differential Diagnosis:** Always differentiate annular lesions from **Tinea Corporis** (which is itchy and has an active scaling border) [2] and **Granuloma Annulare** (which lacks scales). [1] * **Erythema Marginatum** is associated with **Rheumatic Fever**, while **Erythema Multiforme** is often associated with **HSV** or **Mycoplasma**.

Q: A 22-year-old woman developed small itchy wheals after physical exertion, walking in the sun, eating hot spicy food, and when she was angry. What is the most likely diagnosis?

Cholinergic urticaria. ### Explanation **Correct Answer: D. Cholinergic Urticaria** **Why it is correct:** Cholinergic urticaria (CU) is a distinct subtype of physical urticaria triggered by an **increase in core body temperature**. The classic triggers include physical exertion (exercise), exposure to heat (sun/hot baths), emotional stress (anger), and consumption of spicy foods. * **Pathophysiology:** It is mediated by **acetylcholine** released from postganglionic sympathetic nerve fibers supplying the eccrine sweat glands. * **Clinical Presentation:** It is characterized by **small (1–3 mm), punctate, highly pruritic wheals** surrounded by a large area of erythema (flare). This "micropapular" appearance is a hallmark of the condition. **Why other options are incorrect:** * **A. Chronic Idiopathic Urticaria:** This refers to hives occurring daily or almost daily for >6 weeks without an identifiable trigger. It does not specifically correlate with core temperature changes. * **B. Heat Urticaria:** A rare form of localized urticaria occurring only at the site of direct contact with a warm object. It is not triggered by generalized exertion or spicy food. * **C. Solar Urticaria:** This is triggered specifically by exposure to ultraviolet (UV) or visible light, not by exercise or emotional stress. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Test:** The **Provocation Test** (e.g., exercise like running or a hot water bath) is used to confirm the diagnosis. * **Morphology:** Remember the keyword **"Punctate wheals"** or **"Micropapular hives."** * **Treatment:** First-line treatment is **Second-generation H1 antihistamines** (e.g., Cetirizine). In refractory cases, Glycopyrrolate (anticholinergic) or Omalizumab may be used. * **Differential:** Unlike most urticarias, the wheals in CU are much smaller than the surrounding flare.

Q: Cutaneous signs of diabetes mellitus are all except?

Angiokeratomas. **Explanation:** The correct answer is **D. Angiokeratomas**. Angiokeratomas are benign vascular ectasias (dilated capillaries) characterized by dark red to purple papules with a scaly surface. They are classically associated with **Fabry disease** (alpha-galactosidase A deficiency) or can occur idiopathically (e.g., Angiokeratoma of Fordyce). They have no pathophysiological link to Diabetes Mellitus (DM). **Analysis of Incorrect Options:** * **Necrobiosis Lipoidica (NL):** A highly specific (though rare) sign of DM. It presents as yellowish-brown, atrophic, telangiectatic plaques on the pretibial area. It is caused by collagen degeneration and microangiopathy. * **Carotinosis (Carotenemia):** Diabetics often have impaired conversion of beta-carotene to Vitamin A in the liver, leading to yellow discoloration of the skin (especially palms and soles), while the sclera remains white (unlike jaundice). * **Shin Spots:** This is the most common cutaneous manifestation of DM. While the option mentions **Granuloma Annulare (GA)** in parentheses, it is important to note: * **Diabetic Dermopathy (Shin Spots):** Presents as circumscribed, atrophic, hyperpigmented macules on the shins. * **Granuloma Annulare:** Disseminated GA is strongly associated with DM. The question likely groups these as "pretibial/necrobiotic" manifestations common in diabetics. **High-Yield Clinical Pearls for NEET-PG:** * **Most common skin finding in DM:** Diabetic Dermopathy (Shin spots). * **Most specific skin finding in DM:** Necrobiosis Lipoidica. * **Acanthosis Nigricans:** A marker of insulin resistance (Type 2 DM). * **Scleredema Adultorum of Buschke:** Woody induration of the upper back/neck seen in poorly controlled diabetics. * **Bullosis Diabeticorum:** Spontaneous, non-inflammatory blistering, usually on the feet.

Q: Which condition presents with 'Cayenne pepper' stippling due to hemosiderin?

Plasma cell balanitis of Zoon. **Explanation:** **Plasma cell balanitis of Zoon** is a chronic, idiopathic, inflammatory dermatosis typically affecting the glans penis of uncircumcised middle-aged to elderly men. **Why it is correct:** The characteristic clinical appearance is a solitary, well-circumscribed, "glistening" or "lacquered" orange-red plaque. The **"Cayenne pepper" stippling** is a hallmark finding caused by **hemosiderin deposition** within the dermis. This occurs due to the extravasation of red blood cells from dilated, fragile capillary loops (siderophages) in the upper dermis, which is also heavily infiltrated by plasma cells. **Why the other options are incorrect:** * **Erythroplasia of Queyrat:** This is Squamous Cell Carcinoma (SCC) in situ of the glans. While it also presents as a red velvety plaque, it lacks the characteristic hemosiderin stippling and shows full-thickness epidermal dysplasia on histology. * **Paget's disease (Extramammary):** This is an intraepidermal adenocarcinoma. It typically presents as an eczematous, itchy, or scaling plaque. Histology shows "Paget cells" (large cells with clear cytoplasm) rather than plasma cell infiltration or hemosiderin stippling. * **Metronidazole:** This is an antibiotic/antiprotozoal medication and not a clinical condition. It is unrelated to the pathology of pigmented purpuric-like stippling. **NEET-PG High-Yield Pearls:** * **Histology of Zoon’s:** Dense band-like infiltrate of **plasma cells** (>80%), "lozenge-shaped" keratinocytes, and extravasated RBCs. * **Treatment of Choice:** **Circumcision** is considered curative. * **Differential Diagnosis:** Always biopsy to rule out Erythroplasia of Queyrat (malignant) vs. Zoon’s (benign). * **Similar Finding:** "Cayenne pepper spots" are also seen in **Schamberg’s Disease** (Progressive Pigmented Purpuric Dermatosis), also due to hemosiderin.

Question 1

Lines of Blaschko represent:

Accepted Answer

Lines of development

Answer

Lines along lymphatics

Answer

Lines along blood vessels

Answer

Lines of nerves

Question 2

In erythema migrans, which papillae of the tongue are absent?

Accepted Answer

Filiform

Answer

Fungiform

Answer

Foliate

Answer

Circumvallate

Question 3

A 35-year-old woman develops an itchy rash over her back, legs, and trunk several hours after swimming in a lake. Erythematous, edematous papules are noted. The wheals vary in size. There are no mucosal lesions and no swelling of the lips. What is the most likely diagnosis?

Accepted Answer

Urticaria

Answer

Folliculitis

Answer

Erythema multiforme

Answer

Erythema chronicum migrans

Question 4

What is the characteristic finding of a beaded margin of the eyelid?

Accepted Answer

Lipoid proteinosis

Answer

Erythema granuloma annulare

Answer

Leprosy

Answer

Granuloma annulare

Question 5

Multipleround to oval erythematous patches with fine central scale distributed along the skin tension lines on the trunk is highly suggestive of?

Accepted Answer

Pityriasis rosea

Answer

Tinea versicolor

Answer

Lichen planus

Answer

Seborrheic dermatitis

Question 6

A 28-year-old woman with diabetes presents with painless lesions on her leg, characterized by a central depression and raised irregular margins. What is the most likely diagnosis?

Accepted Answer

Necrobiosis lipoidica diabeticorum

Answer

Eruptive xanthomas

Answer

Gangrene

Answer

Staphylococcal infection

Question 7

A child presents with a lesion on the buttocks that has been present for 2 years, spreading peripherally with central scarring and is asymptomatic. What is the most likely diagnosis?

Accepted Answer

Erythema annulare centrifugum

Answer

Erythema migrans

Answer

Erythema marginatum

Answer

Erythema gyratum

Question 8

A 22-year-old woman developed small itchy wheals after physical exertion, walking in the sun, eating hot spicy food, and when she was angry. What is the most likely diagnosis?

Accepted Answer

Cholinergic urticaria

Answer

Chronic idiopathic urticaria

Answer

Heat urticaria

Answer

Solar urticaria

Question 9

Cutaneous signs of diabetes mellitus are all except?

Accepted Answer

Angiokeratomas

Answer

Necrobiosis lipoidica

Answer

Carotinosis

Answer

Shin spots (granuloma annulare)

Question 10

Which condition presents with 'Cayenne pepper' stippling due to hemosiderin?

Accepted Answer

Plasma cell balanitis of Zoon

Answer

Erythroplasia of Queyrat

Answer

Paget's disease

Answer

Metronidazole

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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