Basic Dermatology Practice Questions

Q: Koebner's phenomenon is seen in all except

Tinea corporis. ***Tinea corporis*** - **Koebner's phenomenon**, also known as the isomorphic response, is the appearance of skin lesions characteristic of a **pre-existing dermatosis** at sites of **trauma** to previously uninvolved skin. - **Tinea corporis**, a **superficial fungal infection**, does NOT exhibit true Koebner's phenomenon. - Its spread occurs through **direct fungal contact or autoinoculation**, not through an isomorphic response to non-specific trauma. *Psoriasis* - **Psoriasis** is the **classic example** of Koebner's phenomenon. - New psoriatic plaques can appear at sites of **skin trauma** such as scratches, surgical scars, burns, or tattoos within **10-20 days** of injury. - This occurs in approximately **25-50%** of psoriasis patients. *Warts* - **Warts** (verruca vulgaris), caused by **human papillomavirus (HPV)**, can show what is sometimes called **pseudo-Koebner's phenomenon**. - Trauma facilitates **viral inoculation** and seeding of HPV into the skin, leading to new wart formation along scratch lines. - However, this is technically **viral spread through trauma**, not a true isomorphic response of a pre-existing dermatosis. *Molluscum contagiosum* - **Molluscum contagiosum** can similarly demonstrate **pseudo-Koebner's phenomenon**. - Scratching spreads the **molluscum contagiosum virus** to adjacent areas, creating linear arrays of lesions. - Like warts, this represents **direct viral inoculation** rather than true isomorphic response, but is often grouped with Koebner's phenomenon in clinical practice.

Q: Phrynoderma is a cutaneous manifestation of severe deficiency of vitamin :

Vitamin A. ***Vitamin A*** - **Phrynoderma**, also known as **toad skin** or follicular hyperkeratosis, is a classic cutaneous manifestation of severe **vitamin A deficiency**. - This condition is characterized by **dry, scaly skin** with prominent **follicular papules** due to hyperkeratosis around hair follicles. *Vitamin D* - Deficiency of **vitamin D** is primarily associated with bone diseases like **rickets** in children and **osteomalacia** in adults. - While it can manifest with diffuse musculoskeletal pain and weakness, it does not typically cause the specific follicular hyperkeratosis seen in phrynoderma. *Vitamin C* - **Vitamin C deficiency** leads to **scurvy**, characterized by **gingivitis**, easy bruising, poor wound healing, and **perifollicular hemorrhages**. - Although it affects skin and hair follicles, the appearance of perifollicular hemorrhages is distinct from the hyperkeratotic papules of phrynoderma. *Vitamin B* - **Vitamin B complex deficiencies** can cause a wide range of dermatological issues, such as **pellagra** (niacin/B3 deficiency) with photosensitive dermatitis, or **cheilosis** and **glossitis** (riboflavin/B2 deficiency). - However, deficiencies in B vitamins do not typically present with phrynoderma or follicular hyperkeratosis as their primary cutaneous manifestation.

Q: Erythema nodosum is seen in all of the following except:

Chronic pancreatitis. ***Chronic pancreatitis*** - **Erythema nodosum** is a **panniculitis**, an inflammation of the subcutaneous fat. **Chronic pancreatitis** is generally NOT a recognized cause of erythema nodosum. - Pancreatic diseases, specifically **acute pancreatitis**, can sometimes cause a different type of panniculitis called **pancreatic panniculitis**, characterized by fat necrosis and enzymatic destruction of subcutaneous fat—this is distinct from erythema nodosum. - Chronic pancreatitis does not have this association with either condition. *Tuberculosis* - **Tuberculosis** is one of the most well-established infectious causes of erythema nodosum, especially in endemic regions. - The cell-mediated immune response to mycobacterial antigens triggers the characteristic tender, red subcutaneous nodules. *Pregnancy* - **Pregnancy** is a well-recognized physiological trigger for erythema nodosum due to hormonal changes and altered immune responses. - It typically occurs in the second trimester and is considered one of the common non-pathological causes. *SLE* - **Systemic lupus erythematosus (SLE)** has been reported in association with erythema nodosum, though this is relatively uncommon. - While SLE has numerous cutaneous manifestations (malar rash, discoid lesions, lupus panniculitis), erythema nodosum can occasionally occur as part of the systemic inflammatory response.

Q: On stretching the cheek the lesion disappears in:

Leukoedema. **Leukoedema** - **Leukoedema** is a common, benign, opalescent whitish-gray lesion of the buccal mucosa that **disappears or becomes less noticeable upon stretching the cheek**. - This characteristic disappearance upon stretching is a key diagnostic feature, differentiating it from other white lesions. - It is a developmental variation seen in up to 90% of African Americans and less commonly in other populations. *White sponge nevus* - **White sponge nevus** is a rare hereditary condition presenting as white, thick, folded plaques on the buccal mucosa bilaterally. - Unlike leukoedema, the lesions **do not disappear on stretching** and persist throughout life. - It is caused by mutations in keratin genes and remains constant in appearance. *Focal hyperkeratosis* - **Focal hyperkeratosis** is a thickened white lesion often caused by chronic irritation or friction, and while it may appear whitish, it **does not disappear or diminish upon stretching** the oral mucosa. - The whiteness is due to an excess of keratin, making it a more fixed and persistent lesion. *Leukoplakia* - **Leukoplakia** is a clinical term for a white patch or plaque on the oral mucosa that **cannot be rubbed off** and **cannot be characterized clinically or pathologically as any other disease**. It does not disappear on stretching. - It is considered a potentially malignant disorder, and its persistence with stretching is a significant differentiator from leukoedema.

Q: Acrodermatitis enteropathica is seen with deficiency of?

Zinc. ***Zinc*** - **Acrodermatitis enteropathica** is a rare, inherited disorder characterized by a triad of **dermatitis**, **diarrhea**, and **alopecia**, primarily due to impaired zinc absorption. - **Zinc supplementation** is the cornerstone of treatment and typically leads to rapid resolution of symptoms. *Copper* - Copper deficiency can lead to **anemia**, **neutropenia**, and **neurological symptoms** like ataxia and peripheral neuropathy. - It does not cause the characteristic skin lesions of acrodermatitis enteropathica. *Vitamin A* - Vitamin A deficiency is associated with **xerophthalmia** (dry eyes), **night blindness**, and impaired immune function. - It does not present with acrodermatitis enteropathica. *Iron* - Iron deficiency causes **microcytic hypochromic anemia**, fatigue, and pica. - It does not manifest as the specific dermatological and gastrointestinal symptoms seen in acrodermatitis enteropathica.

Q: "Keratotic sandal" is seen in which of the following?

Pityriasis rubra pilaris. ***Pityriasis rubra pilaris*** - "**Keratotic sandals**" refer to the characteristic **palmoplantar keratoderma** seen in pityriasis rubra pilaris, which gives the soles of the feet a thickened, yellowish appearance. - This condition also typically presents with **follicular papules**, **confluent erythematous plaques**, and often spared areas known as "islands of normal skin." *Tinea versicolor* - This is a **superficial fungal infection** characterized by **hypopigmented or hyperpigmented patches** with fine scaling, most commonly on the trunk and upper extremities. - It does not involve significant palmoplantar keratoderma or the formation of "keratotic sandals." *Sezary syndrome* - Sezary syndrome is an aggressive form of **cutaneous T-cell lymphoma** characterized by **erythroderma**, **lymphadenopathy**, and the presence of **Sezary cells** in the blood. - While skin involvement is extensive, the specific presentation of "keratotic sandals" is not a typical feature of Sezary syndrome. *Reiter's disease* - Reiter's disease, now known as **reactive arthritis**, is a seronegative spondyloarthropathy characterized by arthritis, urethritis, and conjunctivitis. - Skin manifestations can include **keratoderma blennorrhagicum**, which are papules and vesicles that become hyperkeratotic plaques, primarily on the palms and soles, but the term "keratotic sandals" is specifically associated with pityriasis rubra pilaris.

Q: Erythematous ringworm like lesions parallel to the ribs, with hanging curtain sign and Christmas tree pattern is suggestive of:

Pityriasis Rosea. ***Pityriasis Rosea*** - **Pityriasis rosea** classically presents with an initial **herald patch**, followed by smaller, erythematous, oval-shaped lesions that align along the **skin cleavage lines** (Langer's lines), creating a **"Christmas tree" pattern** on the back. - The **"hanging curtain sign"** refers to the way the scales may detach at the periphery, resembling a hanging curtain, often seen with the characteristic ringworm-like lesions. *Pityriasis rubra pilaris* - This condition is characterized by **follicular papules** and **confluent erythematous plaques** with prominent **keratotic plugs**, often forming areas of orange-red scaling. - It typically exhibits an **island of sparing** where small patches of healthy skin are untouched, which is not described by the patient's symptoms. *Psoriasis* - **Psoriasis** presents as well-demarcated, **erythematous plaques** covered with thick, silvery scales, often on extensor surfaces like elbows and knees. - It does not specifically show a "Christmas tree" pattern or a "hanging curtain sign"; instead, it's known for the **Auspitz sign** (bleeding upon scale removal). *Lichen planus* - **Lichen planus** is characterized by **pruritic, purple, polygonal, planar papules and plaques** (the "6 P's"), often with fine white lines called **Wickham's striae**. - It commonly affects the flexor surfaces of wrists, forearms, and ankles, and can involve the oral mucosa, but does not present with ringworm-like lesions in a "Christmas tree" pattern.

Q: The wavelength of a Wood lamp is:

360-385. ***360-385*** - This wavelength range (measured in nanometers) corresponds to **long-wave ultraviolet A (UVA) light**, which is emitted by a Wood lamp. - This specific UVA spectrum is used to cause **fluorescence** in certain dermatological conditions or metabolites, making them visible. *280-320* - This range corresponds to **UVB light**, which is known for causing sunburn and is used in phototherapy for conditions like psoriasis, but not for Wood lamp examination. - Exposure to this wavelength is primarily responsible for **DNA damage** and skin carcinogenesis. *450-500* - These wavelengths fall within the **visible blue light** spectrum. - While various light sources can emit light in this range, it does not correspond to the specific **UV** output of a Wood lamp. *400-450* - This range is at the boundary of **visible violet light** and UVA. - Although it includes some UVA, the primary and most effective range for Wood lamp examinations is slightly lower, specifically the **360-385 nm** range.

Q: In which of the following, Koebner phenomenon is NOT seen -

Lichen simplex chronicus. ***Lichen simplex chronicus*** - The **Koebner phenomenon**, which involves the appearance of skin lesions at sites of trauma, is not typically observed in **lichen simplex chronicus**. - This condition is characterized by **chronic scratching and rubbing**, leading to thickened, leathery skin, but the lesions themselves do not spread to new trauma sites in the classic Koebner fashion. *Psoriasis* - The **Koebner phenomenon** (also known as the isomorphic response) is highly characteristic of psoriasis, where new psoriatic lesions develop in areas of skin trauma. - This response is a key diagnostic feature and helps differentiate psoriasis from other skin conditions. *Lichen planus* - The **Koebner phenomenon** is a well-recognized feature of lichen planus, where the skin lesions can appear along lines of trauma, such as scratches or surgical scars. - This isomorphic response can be helpful in the diagnosis and understanding of the disease pathogenesis. *Lichen nitidus* - **Lichen nitidus** is another dermatological condition in which the **Koebner phenomenon** is observed. - New papules can erupt at sites of minor trauma, indicating an isomorphic response similar to that seen in psoriasis and lichen planus.

Q: Which of the following is not a component of sebum?

Propylene. ***Propylene*** - **Propylene** (or polypropylene) is a synthetic polymer used in plastics and fibers, not a naturally occurring component of human sebum. - Sebum is a complex mixture of lipids produced by the sebaceous glands to lubricate the skin and hair. *Wax* - **Waxes** (specifically wax esters) are a significant component of sebum, contributing to its protective and hydrophobic properties. - These esters are formed from fatty acids and long-chain alcohols. *Glycerides* - **Glycerides**, particularly triglycerides (esters of glycerol and fatty acids), are major components of sebum, making up a large percentage of its total lipid content. - They contribute to the skin's lipid barrier and emollient properties. *Cholesterol* - **Cholesterol** and its esters are also present in sebum, playing a role in maintaining the integrity and fluidity of the skin barrier. - It works alongside other lipids to prevent water loss and protect against external factors.

Question 1

Koebner's phenomenon is seen in all except

Accepted Answer

Tinea corporis

Answer

Psoriasis

Answer

Warts

Answer

Molluscum contagiosum

Question 2

Phrynoderma is a cutaneous manifestation of severe deficiency of vitamin :

Accepted Answer

Vitamin A

Answer

Vitamin D

Answer

Vitamin C

Answer

Vitamin B

Question 3

Erythema nodosum is seen in all of the following except:

Accepted Answer

Chronic pancreatitis

Answer

Tuberculosis

Answer

Pregnancy

Answer

SLE

Question 4

On stretching the cheek the lesion disappears in:

Accepted Answer

Leukoedema

Answer

White sponge nevus

Answer

Focal hyperkeratosis

Answer

Leukoplakia

Question 5

Acrodermatitis enteropathica is seen with deficiency of?

Accepted Answer

Zinc

Answer

Copper

Answer

Vitamin A

Answer

Iron

Question 6

"Keratotic sandal" is  seen in which of the following?

Accepted Answer

Pityriasis rubra pilaris

Answer

Tinea versicolor

Answer

Sezary syndrome

Answer

Reiter's disease

Question 7

Erythematous ringworm like lesions parallel to the ribs, with hanging curtain sign and Christmas tree pattern is suggestive of:

Accepted Answer

Pityriasis Rosea

Answer

Pityriasis rubra pilaris

Answer

Psoriasis

Answer

Lichen planus

Question 8

The wavelength of a Wood lamp is:

Accepted Answer

360-385

Answer

280-320

Answer

450-500

Answer

400-450

Question 9

In which of the following, Koebner phenomenon is NOT seen -

Accepted Answer

Lichen simplex chronicus

Answer

psoriasis

Answer

Lichen planus

Answer

Lichen nitidus

Question 10

Which of the following is not a component of sebum?

Accepted Answer

Propylene

Answer

Wax

Answer

Glycerides

Answer

Cholesterol

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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