Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 211: Yellowish discoloration of oral mucous membrane, skin, and sclera of the eye is characteristic of which condition?

A. Pernicious anemia
B. Sickle cell anemia
C. Chloramphenicol therapy
D. Carotenemia (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Carotenemia** Carotenemia is caused by the excessive intake of carotenoid-rich foods (like carrots, oranges, and squash), leading to high serum levels of beta-carotene. This lipid-soluble pigment deposits in the **stratum corneum**. Clinically, it presents as a yellowish-orange discoloration most prominent on the palms, soles, and nasolabial folds. **Crucial Distinction:** While carotenemia involves the skin and can affect the oral mucosa, it **spares the sclera**. This is the key clinical differentiator from jaundice (icterus), where bilirubin has a high affinity for the elastin-rich sclera. *(Note: The question mentions sclera; however, in the context of the given options, Carotenemia is the most relevant dermatological condition associated with yellow skin discoloration, though classic teaching emphasizes scleral sparing.)* **Why other options are incorrect:** * **Pernicious Anemia:** Typically presents with "lemon-yellow" pallor due to a combination of anemia and mild hemolysis, but it is not a primary pigmentary deposition. * **Sickle Cell Anemia:** May cause jaundice (yellowing of sclera and skin) due to indirect hyperbilirubinemia from chronic hemolysis, but it is not described as a primary "discoloration" therapy or condition in this context. * **Chloramphenicol Therapy:** Classically associated with **"Gray Baby Syndrome"** in neonates, characterized by ashen-gray cyanosis, not yellowing. **High-Yield NEET-PG Pearls:** * **Lycopenemia:** A variant of carotenemia caused by excessive tomato intake; results in a deeper orange-red skin hue. * **Scleral Icterus:** Occurs when serum bilirubin exceeds **2–2.5 mg/dL**. * **Quinacrine/Mepacrine:** An antimalarial drug that can also cause generalized yellow skin discoloration and scleral yellowing.

Question 212: Saw tooth rete pegs are seen in which of the following conditions?

A. Lichen planus (Correct Answer)
B. Leukoplakia
C. Pemphigus vulgaris
D. Psoriasis

Explanation: **Explanation:** **Lichen Planus (Option A)** is the correct answer. The characteristic histopathological hallmark of Lichen Planus is a **"saw-tooth" appearance of the rete pegs**. This occurs due to a dense, band-like lymphocytic infiltrate at the dermo-epidermal junction (interface dermatitis) that causes liquefactive degeneration of the basal cell layer. As the basal layer is destroyed, the epidermis compensates and remodels, leading to the pointed, triangular elongation of the rete ridges resembling the teeth of a saw. **Analysis of Incorrect Options:** * **Leukoplakia (Option B):** This is a clinical term for a white patch. Histologically, it shows hyperkeratosis and epithelial dysplasia, but not the specific saw-tooth pattern. * **Pemphigus Vulgaris (Option C):** This is an autoimmune blistering disease characterized by **acantholysis** (loss of intercellular connections). Key histological features include "row of tombstones" (intact basal layer) and intraepidermal suprabasal blisters. * **Psoriasis (Option D):** Psoriasis features regular elongation of rete ridges, often described as **"test-tube in a rack"** appearance, along with Munro’s microabscesses and Kogoj’s pustules. **High-Yield Clinical Pearls for NEET-PG:** * **Max Joseph Spaces:** Small areas of separation between the epidermis and dermis seen in Lichen Planus. * **Civatte Bodies (Colloid bodies):** Shrunken, eosinophilic apoptotic keratinocytes found in the lower epidermis/upper dermis of Lichen Planus patients. * **Wickham Striae:** The clinical manifestation of hypergranulosis seen as white lacy patterns on the surface of papules or oral mucosa. * **6 P’s of Lichen Planus:** Planar (flat-topped), Purple, Polygonal, Pruritic, Papules, and Plaques.

Question 213: What is true about a keloid scar?

A. Non-familial, common in children, males are more affected.
B. Non-familial, does not outgrow the margin, blacks are affected.
C. Familial, females are more affected, outgrows the margins. (Correct Answer)
D. Familial, males are more affected, whites are affected more.

Explanation: ### Explanation A **keloid** is a benign overgrowth of dense fibrous tissue that results from an abnormal wound-healing response. The hallmark feature that distinguishes it from a hypertrophic scar is that it **extends beyond the original margins** of the wound and rarely regresses spontaneously. **Why Option C is Correct:** * **Familial:** There is a strong genetic predisposition; keloids are more common in individuals with a family history and are frequently seen in darker skin types (African, Asian, and Hispanic populations). * **Gender:** Studies suggest a slightly higher incidence in **females**, often attributed to a higher frequency of ear piercing. * **Margins:** By definition, keloids outgrow the boundaries of the initial injury, invading surrounding healthy skin. **Analysis of Incorrect Options:** * **Option A & B:** Keloids are often **familial** and are most common in the **10–30 age group** (rare in the very young or very old). They are significantly more common in **Blacks** (up to 15 times more frequent) than in Whites. Option B is incorrect because keloids *do* outgrow the margins. * **Option D:** While familial, the statement that males and Whites are more affected is epidemiologically incorrect. **High-Yield Clinical Pearls for NEET-PG:** * **Common Sites:** Presternal area (most common), deltoid, upper back, and earlobes. * **Histopathology:** Characterized by thick, disorganized, "glassy" **Type I and III collagen bundles** (hyalinized collagen). * **Treatment:** Intralesional **Triamcinolone acetonide** (corticosteroid) is the first-line treatment. Other options include cryotherapy, silicone gel sheets, and pressure therapy. * **Surgery Warning:** Simple surgical excision alone has a high recurrence rate (45–100%) and may result in a larger keloid.

Question 214: Angioid streaks in the eyes are seen in which of the following conditions?

A. Pseudoxanthoma elasticum (Correct Answer)
B. Tendinous xanthoma
C. Xanthalasma
D. Eruptive xanthoma

Explanation: **Explanation:** **Pseudoxanthoma Elasticum (PXE)** is the correct answer. It is a multisystem genetic disorder characterized by the progressive calcification and fragmentation of elastic fibers in the skin, eyes, and cardiovascular system. 1. **Why it is correct:** In the eyes, calcification of the elastic lamina of **Bruch’s membrane** leads to cracks or dehiscence. On fundoscopy, these appear as dark, reddish-brown, jagged lines radiating from the optic disc, known as **Angioid Streaks**. Cutaneously, PXE presents as yellowish papules on the neck and flexures, giving a "plucked chicken skin" appearance. 2. **Why other options are incorrect:** * **Tendinous xanthoma:** These are lipid deposits in tendons (commonly the Achilles tendon), typically associated with Familial Hypercholesterolemia. * **Xanthelasma:** These are yellowish plaques on the eyelids caused by localized lipid deposits. While they occur near the eye, they do not involve Bruch's membrane or cause angioid streaks. * **Eruptive xanthoma:** These are small, itchy, yellow-red papules appearing suddenly on extensor surfaces, usually due to severe hypertriglyceridemia. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Angioid Streaks (PEPSI):** **P**seudoxanthoma elasticum, **E**hlers-Danlos syndrome, **P**aget’s disease of bone, **S**ickle cell anemia (and other hemoglobinopathies), **I**diopathic. * **Inheritance of PXE:** Most commonly Autosomal Recessive (ABCC6 gene mutation). * **Systemic Involvement:** Patients are at high risk for premature atherosclerosis, intermittent claudication, and gastrointestinal hemorrhage.

Question 215: A 12-year-old girl presents for a routine physical examination. The patient has numerous freckles over her upper trunk and face. Which of the following terms best describes the morphologic appearance of her freckles?

A. Comedo
B. Macule (Correct Answer)
C. Nodule
D. Papule

Explanation: **Explanation:** The correct answer is **Macule**. **1. Why Macule is Correct:** A **macule** is defined as a flat, circumscribed area of altered skin color that is less than 1 cm in diameter. It is not palpable (you cannot feel it with your eyes closed) because there is no elevation or depression relative to the surrounding skin. Freckles (ephelides) are classic examples of macules; they represent small areas of increased melanin pigment without an increase in the number of melanocytes. **2. Why Other Options are Incorrect:** * **Comedo (A):** This is a primary lesion of acne. It is a "plug" of keratin and sebum within a hair follicle. It can be open (blackhead) or closed (whitehead). * **Nodule (C):** A nodule is a solid, palpable, circumscribed elevation that is larger than 1 cm in diameter and often has a significant dermal or subcutaneous component. * **Papule (D):** A papule is a solid, elevated, palpable lesion that is less than 1 cm in diameter. Unlike a macule, a papule has a distinct vertical dimension. **3. Clinical Pearls for NEET-PG:** * **Macule vs. Patch:** A flat lesion <1 cm is a **macule**; if it is >1 cm, it is called a **patch** (e.g., Vitiligo). * **Papule vs. Plaque:** An elevated lesion <1 cm is a **papule**; a broad, flat-topped elevation >1 cm is a **plaque** (e.g., Psoriasis). * **Freckles (Ephelides):** These darken with sun exposure and are due to increased melanin production. In contrast, **Lentigines** do not darken with sun exposure and are due to a linear hyperplasia of melanocytes. * **Axillary Freckling:** Known as **Crowe’s sign**, this is a high-yield diagnostic feature for Neurofibromatosis Type 1 (NF-1).

Question 216: A 70-year-old male presented with an asymptomatic white patch on the oral cavity following the application of a denture. What is the treatment of choice?

A. Low dose radiotherapy
B. Biopsy of all tissues
C. Ascertaining the denture is fitted properly (Correct Answer)
D. Antibiotics

Explanation: ### Explanation **Diagnosis: Frictional Keratosis** The clinical presentation describes **Frictional Keratosis**, a common reactive condition of the oral mucosa. It occurs due to chronic low-grade mechanical irritation—in this case, an ill-fitting denture. This results in hyperkeratosis, appearing as an asymptomatic, non-detachable white patch (leukoplakia-like). **Why Option C is Correct:** The primary management of frictional keratosis is the **removal of the offending stimulus**. If the white patch is caused by mechanical trauma from a denture, ensuring the denture is fitted properly or adjusted will eliminate the friction. In most cases, the lesion will resolve spontaneously once the irritation ceases. **Analysis of Incorrect Options:** * **Option A (Radiotherapy):** This is contraindicated. Frictional keratosis is a benign reactive process, not a malignancy. Radiotherapy would cause unnecessary morbidity and potential malignant transformation. * **Option B (Biopsy of all tissues):** While a biopsy is indicated if a lesion is suspicious for malignancy or fails to resolve after removing the stimulus, it is not the *initial* treatment of choice for a clear case of mechanical irritation. * **Option D (Antibiotics):** Frictional keratosis is a mechanical/hyperkeratotic issue, not an infectious one. Antibiotics have no role in its management. **NEET-PG High-Yield Pearls:** * **Clinical Tip:** Always differentiate frictional keratosis from **Oral Candidiasis** (which scrapes off) and **Oral Leukoplakia** (a premalignant lesion that does not have an obvious mechanical cause). * **Management Rule:** For any white patch with an identifiable local cause, remove the cause and review in **2–4 weeks**. If the lesion persists, a biopsy is mandatory to rule out dysplasia or squamous cell carcinoma. * **Common Sites:** Buccal mucosa (along the occlusal line/linea alba), lateral tongue, and edentulous ridges.

Question 217: Pruritus is not seen in which of the following conditions?

A. Hyperthyroidism
B. Polycythemia rubra vera
C. Hyperparathyroidism (Correct Answer)
D. Uraemia

Explanation: **Explanation:** Pruritus (itching) is a common systemic manifestation of various metabolic, endocrine, and hematological disorders. To answer this question, one must distinguish between conditions that cause generalized pruritus and those that do not. **Why Hyperparathyroidism is the correct answer:** Primary hyperparathyroidism is generally **not** associated with pruritus. However, it is a common point of confusion because **Secondary Hyperparathyroidism** (occurring in the context of Chronic Kidney Disease) is a major driver of **Uremic Pruritus**. In secondary cases, elevated parathyroid hormone (PTH) levels lead to mast cell degranulation and calcium-phosphate crystal deposition in the skin, causing itch. In the absence of renal failure (Primary Hyperparathyroidism), these mechanisms are typically absent. **Analysis of Incorrect Options:** * **Hyperthyroidism:** Itching is seen in ~4–11% of patients. It is attributed to increased skin temperature, peripheral vasodilation, and increased kinin activity. * **Polycythemia Rubra Vera (PRV):** A classic NEET-PG favorite. It causes **aquagenic pruritus** (stinging/itching after a warm bath) due to histamine release from increased mast cells and basophils. * **Uraemia:** Chronic Kidney Disease (CKD) is one of the most common systemic causes of pruritus. It is multifactorial, involving uremic toxins, xerosis, and the aforementioned secondary hyperparathyroidism. **Clinical Pearls for NEET-PG:** * **Hypothyroidism** also causes pruritus, primarily due to severe skin dryness (xerosis). * **Iron deficiency anemia** is a well-known hematological cause of generalized pruritus, even before anemia develops. * **Obstructive Jaundice:** Pruritus is a hallmark, caused by the accumulation of bile acids and endogenous opioids. * **Most common systemic cause of pruritus:** Chronic Renal Failure (Uraemia).

Question 218: A young male presented with scaly truncal lesions. On examination, genital lesions along with oral 'lace-like' lesions are seen. What is the most likely diagnosis?

A. Lichen planus (Correct Answer)
B. Psoriasis
C. Secondary syphilis
D. Behcet's disease

Explanation: ### Explanation The clinical presentation of scaly truncal lesions associated with oral and genital involvement is classic for **Lichen Planus (LP)**. **1. Why Lichen Planus is correct:** Lichen planus is a chronic inflammatory condition characterized by the "6 Ps": **P**lanar (flat-topped), **P**urple, **P**olygonal, **P**ruritic, **P**apules, and **P**laques. * **Oral Lesions:** The "lace-like" white reticular pattern described is known as **Wickham striae**, a pathognomonic feature of oral LP. * **Genital Involvement:** LP frequently affects the glans penis (often in an annular configuration). * **Scaly Lesions:** While LP papules have a thin, adherent scale, the combination of mucosal and cutaneous involvement strongly points toward this diagnosis. **2. Why other options are incorrect:** * **Psoriasis:** Presents with silvery-white micaceous scales and the Auspitz sign. While it can affect the genitals, it rarely involves the oral mucosa (except in very rare geographic tongue-like patterns). * **Secondary Syphilis:** Known as the "Great Mimicker," it presents with a generalized maculopapular rash involving palms and soles. Oral lesions are typically "snail-track ulcers" or mucous patches, not a reticulate lace-like pattern. * **Behcet’s Disease:** Characterized by the triad of painful aphthous oral ulcers, genital ulcers, and uveitis. It does not typically present with scaly truncal papules or Wickham striae. **Clinical Pearls for NEET-PG:** * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo). * **Histopathology:** Shows "saw-tooth" rete ridges, basal cell degeneration (liquefaction necrosis), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Civatte Bodies:** Degenerated keratinocytes found in the lower epidermis/upper dermis. * **Treatment:** Topical corticosteroids are the first-line treatment.

Question 219: In lichen planus, what are the shrunken basal cells with eosinophilic cytoplasm and pyknotic, fragmented nuclei called?

A. Tzanck cells
B. Civatte bodies (Correct Answer)
C. Donovan bodies
D. Rushton bodies

Explanation: In **Lichen Planus**, the primary pathology involves a T-cell mediated autoimmune attack on the basal cell layer of the epidermis. This leads to **liquefactive degeneration** of the basal keratinocytes. ### **Explanation of the Correct Answer** **Civatte bodies** (also known as colloid, hyaline, or cytoid bodies) are the hallmark histopathological feature of this process. They represent apoptotic or degenerated keratinocytes that have shrunken and fallen into the papillary dermis. Under the microscope, they appear as **round, eosinophilic (pink) bodies** with pyknotic (shrunken) or fragmented nuclei. On direct immunofluorescence (DIF), they characteristically show **globular deposits of IgM**. ### **Explanation of Incorrect Options** * **A. Tzanck cells:** These are rounded, acantholytic keratinocytes found in the floor of vesicles in conditions like **Pemphigus vulgaris** or **Herpes simplex**. * **C. Donovan bodies:** These are intracellular inclusions (resembling safety pins) seen within macrophages in **Granuloma Inguinale** (*Klebsiella granulomatis*). * **D. Rushton bodies:** These are eosinophilic, linear, or curved calcified structures found in the epithelial lining of **Odontogenic cysts**. ### **High-Yield Pearls for NEET-PG** * **Histopathology of Lichen Planus:** Remember the "Saw-tooth" appearance of rete ridges, Max-Joseph spaces (clefts at the DE junction), and a band-like lymphohistiocytic infiltrate. * **Wickham Striae:** The clinical white lacy patterns correspond histologically to **focal hypergranulosis**. * **Civatte bodies** are not pathognomonic for Lichen Planus; they can also be seen in Lupus Erythematosus and Erythema Multiforme, but are most numerous in LP.

Question 220: A 77-year-old Asian woman reports developing skin abscesses and oral ulcers following minor trauma. What is the most likely diagnosis?

A. Pyoderma Gangrenosum
B. Behcet disease (Correct Answer)
C. Darier's disease
D. Bullous pemphigoid

Explanation: **Explanation:** The clinical presentation of skin abscesses (pseudofolliculitis or sterile pustules) and oral ulcers triggered by minor trauma points toward **Behcet disease**. The key underlying concept here is **Pathergy**, a phenomenon where minor trauma (like a needle prick or a scratch) leads to the formation of a papule or pustule within 24–48 hours. * **Behcet Disease (Correct):** This is a multisystem inflammatory perivasculitis. The classic triad includes recurrent oral aphthous ulcers, genital ulcers, and uveitis. The "skin abscesses" following trauma described in the question represent a positive pathergy test, which is highly specific for Behcet disease, especially in populations from the "Silk Road" (Asian/Middle Eastern descent). **Why other options are incorrect:** * **Pyoderma Gangrenosum:** While it also exhibits pathergy, it typically presents as a rapidly enlarging, painful ulcer with a violaceous, undermined border, rather than multiple abscesses and oral ulcers. * **Darier’s Disease:** An autosomal dominant genodermatosis characterized by greasy, hyperkeratotic papules in seborrheic areas and nail changes (V-shaped nicking). It is not associated with trauma-induced abscesses. * **Bullous Pemphigoid:** An autoimmune blistering disorder seen in the elderly, characterized by tense bullae and intense pruritus. It does not typically present with pathergy or recurrent oral ulcers as a primary feature. **NEET-PG High-Yield Pearls:** * **Pathergy Test:** Positive in Behcet disease, Pyoderma Gangrenosum, and Sweet Syndrome. * **Behcet Genetics:** Strongly associated with **HLA-B51**. * **Magic Syndrome:** A rare variant where features of Behcet disease overlap with Relapsing Polychondritis (Mouth And Genital ulcers with Inflamed Cartilage).

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