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: 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: 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 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: Phrynoderma is primarily associated with a deficiency of which of the following?

Vitamin A. ***Vitamin A*** - **Phrynoderma** (toad skin) has been **classically attributed to vitamin A deficiency** in traditional medical literature and was the accepted answer in historical examinations. - It presents as **follicular hyperkeratosis** with dry, scaly, rough skin having prominent hair follicles with a sandpaper-like texture. - However, **modern evidence** suggests phrynoderma is a **multifactorial condition** often involving **multiple nutritional deficiencies**, with vitamin A being one important contributor among others. *Essential fatty acid* - Deficiency of **essential fatty acids** (linoleic and alpha-linolenic acid) causes **skin dryness, flakiness, and follicular hyperkeratosis**. - **Recent studies** indicate EFA deficiency may play a **significant role** in phrynoderma, particularly in developing countries where multiple nutritional deficiencies coexist. - The clinical presentation can closely mimic vitamin A deficiency-related skin changes. *Vitamin D* - Deficiency of **vitamin D** primarily causes **rickets** in children and **osteomalacia** in adults with bone pain, muscle weakness, and skeletal deformities. - While vitamin D has roles in skin health, its deficiency does not directly cause the follicular hyperkeratosis characteristic of phrynoderma. *Niacin* - **Niacin (vitamin B3)** deficiency causes **pellagra** with the classic \"3 Ds\": **dermatitis, diarrhea, and dementia**. - Pellagra dermatitis is typically **symmetrical in sun-exposed areas** with redness, scaling, and hyperpigmentation—distinctly different from the follicular pattern of phrynoderma.

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

Ocular and cutaneous features. ***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.

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.

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

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 5

Lines of Blaschko are related to?

Accepted Answer

Keratinocytes

Answer

Blood vessels

Answer

Nerves

Answer

Bones

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

Phrynoderma is primarily associated with a deficiency of which of the following?

Accepted Answer

Vitamin A

Answer

Essential fatty acid

Answer

Vitamin D

Answer

Niacin

Question 9

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

Accepted Answer

Ocular and cutaneous features

Answer

Autosomal dominant

Answer

Associated with abnormality in lipid metabolism

Answer

Never associated with neurological involvement

Question 10

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

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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