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: 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: 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: 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: Miliaria arises from obstruction of ?

Eccrine sweat glands. ***Eccrine sweat glands*** - Miliaria, commonly known as **prickly heat**, occurs due to the obstruction of the **eccrine sweat ducts**. - This obstruction traps sweat beneath the skin, leading to inflammation and characteristic rash. *Apocrine sweat glands* - **Apocrine glands** are primarily located in the axillae and anogenital region and are associated with body odor, not miliaria. - Obstruction of apocrine glands can lead to conditions like **hidradenitis suppurativa**, which is distinct from miliaria. *Sebaceous glands* - **Sebaceous glands** produce sebum and are responsible for conditions like **acne vulgaris** when their ducts become clogged. - They are not involved in sweat production or the pathology of miliaria. *Ectopic sebaceous glands* - **Ectopic sebaceous glands** are sebaceous glands found in unusual locations, such as Fordyce spots in the mouth or Montgomery glands in the areola. - While they produce sebum, their obstruction is unrelated to the development of miliaria.

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

Keratinocyte. ***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.

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

They are typically pedunculated.. ***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 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

Lines of Blaschko are related to?

Accepted Answer

Keratinocytes

Answer

Blood vessels

Answer

Nerves

Answer

Bones

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

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

Accepted Answer

Lichen planus

Answer

Addison's disease

Answer

DM

Answer

Hypothyroidism

Question 6

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 7

Miliaria arises from obstruction of ?

Accepted Answer

Eccrine sweat glands

Answer

Apocrine sweat glands

Answer

Sebaceous glands

Answer

Ectopic sebaceous glands

Question 8

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

Accepted Answer

Keratinocyte

Answer

Neutrophil

Answer

Lymphocyte

Answer

Fibroblast

Question 9

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 10

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

Accepted Answer

They are typically pedunculated.

Answer

They commonly occur on the neck and axilla.

Answer

They have malignant potential.

Answer

They are associated with seborrhoeic keratosis.

Basic Dermatology — MCQs

Basic Dermatology — MCQs

On this page

Practice by Chapter

Want unlimited practice?