Basic Dermatology — MCQs

Basic Dermatology Indian Medical PG Practice Questions and MCQs

Question 341: What do the Lines of Blaschko represent?

A. Patterns along lymphatics
B. Patterns along blood vessels
C. Patterns along nerves
D. Patterns of cell migration (Correct Answer)

Explanation: ***Patterns of cell migration*** - The **Lines of Blaschko** are invisible patterns in the skin reflecting the **movement and proliferation of cells** during embryonic development. - They become apparent in certain genetic conditions or mosaics when affected cells form streaks or swirls following these lines. *Patterns along lymphatics* - **Lymphatic patterns** refer to the distribution of the lymphatic system, which drains interstitial fluid and immune cells. - Skin conditions involving lymphatics often present as **lymphedema** or **lymphangitis**, which do not typically follow Blaschko's lines. *Patterns along blood vessels* - **Vascular patterns** describe the distribution of blood vessels in the skin, which can be affected in conditions like **livedo reticularis** or **vasculitis**. - These are distinct from Blaschko's lines, which are embryological in origin and not directly related to vascular anatomy. *Patterns along nerves* - **Nerve patterns** in the skin, such as **dermatomes**, correspond to the sensory innervation supplied by spinal nerves. - While some skin conditions can follow dermatomal distributions (e.g., **herpes zoster**), these are distinct from the embryological migration patterns represented by Blaschko's lines.

Question 342: Acanthosis nigricans is characterized by all of the following except?

A. Associated with thick skin with hyperpigmentation
B. May be a sign of internal malignancy
C. Common in obese people
D. Histologically there is hypermelanosis (Correct Answer)

Explanation: ***Histologically there is hypermelanosis*** - This statement is **FALSE** and is the correct answer to this "EXCEPT" question - The characteristic dark appearance of acanthosis nigricans is **NOT due to increased melanin** (hypermelanosis) - Histologically, the key features are **hyperkeratosis, papillomatosis, and mild acanthosis** - There is typically **minimal or no increase in melanocytes or melanin pigment** - The hyperpigmentation seen clinically is an optical effect from the thickened, hyperkeratotic epidermis *May be a sign of internal malignancy* - This statement is **true**; acanthosis nigricans can be a paraneoplastic syndrome associated with internal malignancies - **Malignant acanthosis nigricans** is particularly associated with **gastrointestinal adenocarcinomas** (especially gastric) - This form typically has sudden onset, rapid progression, and more widespread involvement *Common in obese people* - This statement is **true**; acanthosis nigricans is frequently associated with **insulin resistance** - Commonly seen in individuals with **obesity, type 2 diabetes, and metabolic syndrome** - This benign form typically affects flexural areas (neck, axillae, groin) *Associated with thick skin with hyperpigmentation* - This statement is **true**; these are the hallmark clinical features of acanthosis nigricans - Presents as **velvety thickening** and **dark brown to black hyperpigmentation** - Typically affects intertriginous areas and skin folds

Question 343: What percentage of skin involvement is characteristic of erythroderma?

A. More than 90% (Correct Answer)
B. Less than 30%
C. 30% to 60%
D. 60% to 70%

Explanation: ***More than 90%*** - Erythroderma, also known as **exfoliative dermatitis**, is defined by diffuse redness and scaling involving **more than 90% of the body surface area**. - This extensive involvement leads to significant physiological disturbances due to impaired skin barrier function. *Less than 30%* - Skin involvement less than 30% does not meet the criteria for erythroderma and would be considered more localized dermatological conditions. - This percentage of involvement would typically indicate a benign rash or localized eczema, not a widespread inflammatory process. *30% to 60%* - While significant, 30% to 60% skin involvement is still insufficient to classify a condition as erythroderma. - This range might be seen in severe but still localized forms of conditions like psoriasis or eczema. *60% to 70%* - 60% to 70% involvement is extensive but falls short of the critical threshold for erythroderma. - Although indicating widespread disease, it does not constitute the near-total body erythema and scaling characteristic of erythroderma.

Question 344: Lines of Blaschko are related to?

A. Keratinocytes (Correct Answer)
B. Blood vessels
C. Nerves
D. Bones

Explanation: ***Keratinocytes*** - **Lines of Blaschko** represent the migratory pathways of embryonic cells, primarily **keratinocytes**, in the skin. - These lines are not visible under normal conditions but become apparent in various **genetic skin disorders** where abnormal cells follow these specific patterns. *Blood vessels* - While blood vessels are extensively present in the skin, they do not follow the specific **migratory patterns** described by the Lines of Blaschko. - Their arrangement is more related to **vascular networks** and anatomical supply rather than embryonic cell migration. *Nerves* - **Nerves** in the skin have specific distributions, often following dermatomal patterns, which are distinct from the **Lines of Blaschko**. - Nerve distribution is related to their segmental origin from the **spinal cord**, not the migratory paths of epidermal cells. *Bones* - **Bones** are part of the skeletal system and are not found in the skin, making them unrelated to the **Lines of Blaschko**. - These lines describe epidermal cell migration, which is a feature of the **integumentary system**.

Question 345: Which of the following is the MOST characteristic feature of skin tags (acrochordons)?

A. They commonly occur on the neck and axilla.
B. They have malignant potential.
C. They are associated with seborrhoeic keratosis.
D. They are typically pedunculated. (Correct Answer)

Explanation: ***They are typically pedunculated.*** - **Skin tags (acrochordons)** are benign soft tissue tumors characterized by their **pedunculated morphology** - they are attached to the skin by a narrow stalk or pedicle. - This **pedunculated appearance** is the **most characteristic** and **defining feature** that distinguishes them from other benign skin lesions. - They are typically **soft, flesh-colored or hyperpigmented**, and range from 1-5 mm in size. *They commonly occur on the neck and axilla.* - While **skin tags** frequently occur in areas of friction such as the neck, axilla, eyelids, groin, and inframammary folds, this **location is not specific**. - Many other skin conditions also favor these sites, so location alone is not a characteristic diagnostic feature. *They are associated with seborrhoeic keratosis.* - There is **no established clinical association** between skin tags and seborrheic keratoses. - Both are common **benign skin growths** in adults but represent different pathological entities with different clinical appearances. *They have malignant potential.* - This is **incorrect**. Skin tags are **benign fibrous polyps** with **no malignant potential**. - They do not require removal unless symptomatic or for cosmetic reasons.

Question 346: Which of the following pairs of conditions is incorrectly matched?

A. Erythema gyratum repens - malignancy
B. Erythema marginatum - rheumatic fever
C. Necrotic acral erythema - HCV
D. Erythema chronicum migrans - malignancy (Correct Answer)

Explanation: ***Erythema chronicum migrans - malignancy*** - **Erythema chronicum migrans** is the characteristic skin lesion of **Lyme disease**, caused by the bacterium *Borrelia burgdorferi*, transmitted by ticks. - It is not associated with malignancy; rather, its presence indicates a **bacterial infection** requiring antibiotic treatment. *Erythema marginatum - rheumatic fever* - **Erythema marginatum** is a **major diagnostic criterion** for **rheumatic fever**, a post-streptococcal inflammatory disease. - The rash is characterized by non-itchy, pink or red macules with raised, serpiginous borders that spread outwards, often transient. *Erythema gyratum repens - malignancy* - **Erythema gyratum repens** is a rare **paraneoplastic dermatosis** strongly associated with various internal malignancies, most commonly lung cancer. - It presents as a characteristic **wood-grain-like pattern** of concentric, migratory erythematous bands. *Necrotic acral erythema - HCV* - **Necrotic acral erythema** is a skin condition that predominantly affects the hands and feet and has a strong association with **hepatitis C virus (HCV) infection**. - It presents with violaceous plaques that can ulcerate and become necrotic, often in patients with chronic HCV.

Question 347: What type of cell are Tzanck cells commonly associated with in skin conditions?

A. Keratinocyte (Correct Answer)
B. Neutrophil
C. Lymphocyte
D. Fibroblast

Explanation: ***Keratinocyte*** - **Tzanck cells** are **acantholytic keratinocytes** characterized by loss of intercellular connections, resulting in rounded cells with **large nuclei** and **perinuclear halos**. - They are classically seen in **pemphigus vulgaris** and other acantholytic disorders on **Tzanck smear** preparation. - The Tzanck smear is a simple bedside diagnostic test where the base of a blister is scraped and examined microscopically after staining. *Fibroblast* - **Fibroblasts** are mesenchymal cells in the **dermis** that produce **collagen** and extracellular matrix components. - They are not epithelial cells and do not undergo acantholysis to form Tzanck cells. *Neutrophil* - **Neutrophils** are polymorphonuclear leukocytes involved in acute inflammatory responses and fighting bacterial infections. - They may infiltrate skin lesions but do not transform into Tzanck cells, which are specifically altered keratinocytes. *Lymphocyte* - **Lymphocytes** (T cells and B cells) are immune cells involved in **adaptive immunity**. - They are not the cell type from which Tzanck cells originate; Tzanck cells are acantholytic epidermal keratinocytes.

Question 348: The appearance described as an inverted champagne bottle is associated with which condition?

A. Varicose veins
B. Deep vein thrombosis
C. Venous ulceration
D. Lipodermatosclerosis (Correct Answer)

Explanation: ***Lipodermatosclerosis*** - This condition presents with a characteristic "inverted champagne bottle" appearance, where the **ankle area is narrow** and the **calf area above it is wider** due to fibrotic changes and fat atrophy. - It's a severe manifestation of **chronic venous insufficiency**, characterized by **skin hardening**, pigmentation, and inflammation, often preceding venous ulceration. *Varicose veins (enlarged, twisted veins)* - While associated with **venous insufficiency**, varicose veins themselves are **dilated, tortuous superficial veins**, and do not typically cause the generalized lower leg shape change described. - They may cause swelling and discomfort but do not directly lead to the **fibrotic narrowing** seen in an "inverted champagne bottle" leg. *Deep vein thrombosis (DVT) (acute venous obstruction)* - DVT is an **acute condition** involving a **blood clot in a deep vein**, leading to sudden onset pain, swelling, and redness. - It does not cause the **chronic skin changes** and **fibrotic reshaping** of the calf and ankle that characterize lipodermatosclerosis. *Venous ulceration (open sores due to venous insufficiency)* - Venous ulcers are **open sores** that occur in severe chronic venous insufficiency, often found above the medial malleolus. - While they are a complication of the underlying venous disease that can also cause lipodermatosclerosis, the ulceration itself is a **skin lesion**, not the **overall inverted champagne bottle shape** of the leg.

Question 349: Richner-Hanhart syndrome is characterized by which of the following?

A. Autosomal dominant
B. Associated with abnormality in lipid metabolism
C. Ocular and cutaneous features (Correct Answer)
D. Never associated with neurological involvement

Explanation: ***Ocular and cutaneous features*** - **Richner-Hanhart syndrome**, also known as **Tyrosinemia type II**, is characterized by the classic triad of **painful hyperkeratotic plaques** on the palms and soles (cutaneous features), **corneal ulcers** or **dendritic keratitis** (ocular features), and **variable neurological involvement**. - These features arise from the accumulation of **tyrosine** due to a deficiency of the enzyme **hepatic tyrosine aminotransferase (TAT)**. - The **ocular and cutaneous manifestations** are the hallmark features that define this syndrome. *Autosomal dominant* - Richner-Hanhart syndrome is inherited in an **autosomal recessive** pattern, meaning two copies of the defective gene (TAT gene on chromosome 16) are required for the condition to manifest. - An **autosomal dominant** inheritance pattern would mean only one copy of the defective gene is sufficient to cause the disorder. *Associated with abnormality in lipid metabolism* - The syndrome is an inborn error of **amino acid metabolism**, specifically involving **tyrosine**, not lipid metabolism. - Diseases associated with abnormality in **lipid metabolism** include conditions like Gaucher disease, Niemann-Pick disease, or Fabry disease. *Never associated with neurological involvement* - This is **incorrect**. **Neurological involvement** including intellectual disability, developmental delay, seizures, and behavioral problems occurs in **30-50% of cases**. - The accumulation of **tyrosine** and its metabolites (particularly tyrosine crystals) can be **neurotoxic**, leading to varying degrees of neurological impairment. - Early dietary restriction of tyrosine and phenylalanine can prevent or minimize neurological complications.

Question 350: Loss of intercellular cohesion between keratinocytes is referred to as?

A. Acanthosis
B. Acantholysis (Correct Answer)
C. Keratinolysis
D. Spongiosis

Explanation: ***Acantholysis*** - This term specifically refers to the **loss of cohesion between keratinocytes** in the epidermis due to the breakdown of desmosomal attachments. - It is a hallmark feature of several **blistering skin diseases**, such as pemphigus. *Acanthosis* - This refers to the **thickening of the stratum spinosum** (prickle cell layer) of the epidermis, often due to an increase in the number of keratinocytes. - It is seen in conditions like **psoriasis** and seborrheic keratosis, but does not involve a loss of intercellular cohesion. *Keratinolysis* - This term describes the **breakdown or dissolution of keratin**, which is the primary structural protein of the epidermis. - While keratinocytes produce keratin, keratinolysis itself is not the specific term for loss of cohesion between these cells. *Spongiosis* - This is defined as **intercellular edema** (fluid accumulation) within the epidermis, especially prominent in the stratum spinosum. - It leads to the widening of intercellular spaces and stretching of desmosomes, but the cells generally remain attached, unlike in acantholysis.

Practice by Chapter

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Dermatological Procedures

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Cutaneous Immunology

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