Basic Dermatology Practice Questions

Q: What do the Lines of Blaschko represent?

Patterns of cell migration. ***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.

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

Histologically there is hypermelanosis. ***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

Q: What is the primary purpose of UV rays examination in dermatology?

Assessing pigmentary disorders. ***Assessing pigmentary disorders*** - **UV light** (specifically **Wood's lamp** examination) enhances the contrast between pigmented and non-pigmented areas of the skin, making **vitiligo**, **melasma**, and other **pigmentary changes** more apparent. - This increased visibility allows for better delineation of lesion borders and estimation of the extent of pigmentary abnormalities, aiding in diagnosis and treatment planning. - This is the **most common and primary clinical application** of Wood's lamp in dermatology. *Diagnosing fungal infections* - While a **Wood's lamp** can sometimes highlight certain fungal infections like **tinea capitis** caused by **Microsporum species** (due to **fluorescence**), it is not the primary or definitive diagnostic tool. - **Microscopy with KOH prep** and **fungal culture** are the gold standard for diagnosing fungal infections. - Most modern dermatophytes do not fluoresce, limiting its utility. *Detecting porphyria* - Certain types of **porphyria** (e.g., **porphyria cutanea tarda**) can cause **red-pink fluorescence of urine** or teeth under **UV light**, but this is a systemic finding, not a primary dermatological examination purpose. - Diagnosis of **porphyria** primarily relies on **laboratory tests** measuring porphyrin levels in blood, urine, and stool. *Detecting bacterial infections* - While certain bacteria (such as **Corynebacterium minutissimum** causing **erythrasma**) show **coral-red fluorescence** under Wood's lamp, this is a specific diagnostic application, not the primary purpose. - Most bacterial skin infections do not fluoresce, and culture/clinical examination remain the primary diagnostic methods.

Q: Lines of Blaschko are related to?

Keratinocytes. ***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**.

Q: What percentage of skin involvement is characteristic of erythroderma?

More than 90%. ***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.

Q: What is the medical term for the condition characterized by excessive sweating?

Hyperhidrosis. ***Hyperhidrosis*** - This term directly translates to **"excessive sweating"**, with "hyper-" meaning excessive and "hidrosis" referring to sweating. - It describes a condition where the body produces more sweat than is necessary to regulate body temperature. *Anhidrosis* - **Anhidrosis** refers to the **absence of sweating**, which is the opposite of excessive sweating [2]. - Individuals with anhidrosis may be unable to cool themselves effectively, leading to overheating [2]. *Hypohidrosis* - **Hypohidrosis** describes **decreased sweating**, a reduction in the normal amount of sweat produced. - It is less severe than anhidrosis but can still impair the body's ability to regulate temperature. *Normal sweating* - This option refers to the physiological process of sweating in appropriate amounts to **regulate body temperature** in response to heat or exercise [1], [3]. - It implies that there is no abnormal excess or deficiency in sweat production.

Q: Itchy purple papule followed by hyperpigmentation on resolution, is seen in?

Lichen planus. ***Correct: Lichen planus*** - This condition presents with characteristic **pruritic (itchy) violaceous (purple) papules** that often develop **post-inflammatory hyperpigmentation** upon resolution. - The classic presentation follows the **"5 P's": Purple, Pruritic, Polygonal, Planar, Papules**. - Lesions commonly affect the **wrists, ankles, lower back, and genitals**, and may also involve the **oral mucosa** (Wickham's striae). - The hyperpigmentation on resolution is due to **melanin incontinence** and dermal melanophages. *Incorrect: Addison's disease* - Characterized by **hyperpigmentation**, but this is typically diffuse, affecting sun-exposed areas, pressure points, and mucous membranes (e.g., gum line), not discrete papules. - The pigmentation is due to increased **ACTH stimulating melanocytes**, without an initial itchy papular stage. *Incorrect: DM (Diabetes Mellitus)* - Diabetes Mellitus can cause various skin manifestations, including **acanthosis nigricans**, necrobiosis lipoidica diabeticorum, and diabetic dermopathy. - These manifestations do not typically present as itchy purple papules followed by hyperpigmentation, but rather as thickened, velvety skin folds or atrophic, pigmented lesions. *Incorrect: Hypothyroidism* - Can lead to **dry, coarse skin**, and occasionally **non-pitting edema** (myxedema). - It does not present with itchy purple papules or lesions that resolve with hyperpigmentation.

Q: Which of the following pairs of conditions is incorrectly matched?

Erythema chronicum migrans - malignancy. ***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.

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

Acantholysis. ***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.

Q: Which of the following statements about spider telangiectasia is false?

More common in males. ***More common in males*** - This statement is **FALSE** because spider telangiectasias (spider nevi/spider angiomas) are more commonly observed in **females**, often due to hormonal influences like **estrogen**. - They are frequently associated with conditions such as **pregnancy**, **oral contraceptive use**, or **chronic liver disease**, highlighting a female predominance. - The estrogen-dependent nature explains their higher prevalence in women of reproductive age. *Can be caused by trauma* - This statement is **TRUE** in a broader sense, though classical spider telangiectasias are primarily hormonally-mediated rather than traumatic. - While **simple telangiectasias** can develop after localized trauma or repeated pressure, spider telangiectasias have a characteristic morphology (central arteriole with radiating vessels) and are typically associated with **estrogen excess** or **liver disease**. - For exam purposes, this is considered a true statement as telangiectatic vessels can be influenced by local factors. *Light therapy for treatment* - This statement is **TRUE**. **Laser therapy**, specifically **pulsed dye laser (PDL)** or **intense pulsed light (IPL)**, is the most effective treatment for spider telangiectasias. - The laser selectively targets **hemoglobin** in the dilated vessels, causing photocoagulation and vessel obliteration, leading to excellent cosmetic results. *May be associated with liver disease* - This statement is **TRUE**. Spider telangiectasias are a well-recognized cutaneous manifestation of **chronic liver disease**, especially **cirrhosis**. - Impaired hepatic function leads to decreased **estrogen metabolism** (hyperestrogenemia), contributing to the development of these vascular lesions. - They are one of the stigmata of chronic liver disease, along with palmar erythema and gynecomastia.

Question 1

What do the Lines of Blaschko represent?

Accepted Answer

Patterns of cell migration

Answer

Patterns along lymphatics

Answer

Patterns along blood vessels

Answer

Patterns along nerves

Question 2

Acanthosis nigricans is characterized by all of the following except?

Accepted Answer

Histologically there is hypermelanosis

Answer

Associated with thick skin with hyperpigmentation

Answer

May be a sign of internal malignancy

Answer

Common in obese people

Question 3

What is the primary purpose of UV rays examination in dermatology?

Accepted Answer

Assessing pigmentary disorders

Answer

Detecting porphyria

Answer

Diagnosing fungal infections

Answer

Detecting bacterial infections

Question 4

Lines of Blaschko are related to?

Accepted Answer

Keratinocytes

Answer

Blood vessels

Answer

Nerves

Answer

Bones

Question 5

What percentage of skin involvement is characteristic of erythroderma?

Accepted Answer

More than 90%

Answer

Less than 30%

Answer

30% to 60%

Answer

60% to 70%

Question 6

What is the medical term for the condition characterized by excessive sweating?

Accepted Answer

Hyperhidrosis

Answer

Hypohidrosis

Answer

Anhidrosis

Answer

Normal sweating

Question 7

Itchy purple papule followed by hyperpigmentation on resolution, is seen in?

Accepted Answer

Lichen planus

Answer

Addison's disease

Answer

DM

Answer

Hypothyroidism

Question 8

Which of the following pairs of conditions is incorrectly matched?

Accepted Answer

Erythema chronicum migrans - malignancy

Answer

Erythema gyratum repens - malignancy

Answer

Erythema marginatum - rheumatic fever

Answer

Necrotic acral erythema - HCV

Question 9

Loss of intercellular cohesion between keratinocytes is referred to as?

Accepted Answer

Acantholysis

Answer

Acanthosis

Answer

Keratinolysis

Answer

Spongiosis

Question 10

Which of the following statements about spider telangiectasia is false?

Accepted Answer

More common in males

Answer

Light therapy for treatment

Answer

May be associated with liver disease

Answer

Can be caused by trauma

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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