NEET-PG 2015 — Dermatology

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. [Practice more Dermatology PYQs on OnCourse]

Q: HLA-Cw6 is associated with

Psoriasis vulgaris. ***Psoriasis vulgaris*** - **HLA-Cw6** is the **strongest genetic risk factor** associated with an increased susceptibility to psoriasis vulgaris, particularly early-onset forms. - Its presence is linked to a more severe and widespread presentation of the disease. *Myasthenia gravis* - This autoimmune disorder is primarily associated with **HLA-DR3** and **HLA-B8**, and autoantibodies against the acetylcholine receptor. - While other HLA alleles may be involved, **HLA-Cw6** is not a primary or strong genetic association for myasthenia gravis. *Behcet's disease* - **HLA-B51** is the most significant genetic association with Behcet's disease, particularly in populations of Middle Eastern and East Asian descent. - Symptoms include **recurrent oral and genital ulcers**, **uveitis**, and skin lesions. *Pemphigus vulgaris* - This autoimmune blistering disease is strongly associated with **HLA-DR4** and **HLA-DRw6**, especially in individuals of Jewish descent. - It involves autoantibodies targeting **desmoglein 1 and 3**, leading to acantholysis within the epidermis. [Practice more Dermatology PYQs on OnCourse]

Q: Which area is typically not involved in a chickenpox rash?

Palms and soles. ***Palms and soles*** - The chickenpox rash, caused by the **varicella-zoster virus**, typically spares the palms and soles. - Chickenpox exhibits a characteristic **centripetal distribution** (center-predominant), with lesions most numerous on the trunk and progressively fewer on the extremities. - **Sparing of palms and soles** is a classic differentiating feature from other viral exanthems like hand-foot-and-mouth disease. *Trunk* - The **trunk** is usually the **most heavily involved area** in a chickenpox rash, with lesions often appearing first and being most numerous here. - This is the hallmark of the characteristic **centripetal distribution** of the rash. *Axilla* - The **axilla** is a common site for chickenpox lesions due to its location on the trunk and the presence of **warm, moist skin folds** that can favor lesion development. - The rash tends to be widespread, making secondary sites like the axilla commonly involved. *Back* - The **back** is a major part of the trunk and is therefore extensively involved in a chickenpox rash. - The rash often starts on the trunk and spreads outwards, ensuring significant involvement of the back. [Practice more Dermatology PYQs on OnCourse]

Q: Which of the following statements about actinic lichen planus is false?

Associated with severe pruritus. ***Associated with severe pruritus*** - While other forms of lichen planus, especially the typical cutaneous type, are often associated with **severe pruritus**, actinic lichen planus is typically characterized by **mild or absent pruritus**. - Its presentation is often more focused on pigmentary changes and papules in sun-exposed areas rather than intense itching. *Autoimmune etiology* - **Lichen planus**, including its actinic variant, is recognized as an **autoimmune disease**. - It involves a **T-cell-mediated immune response** against basal keratinocytes. *Violaceous brown papules* - Actinic lichen planus commonly presents with **violaceous, brown, or hyperpigmented papules and plaques**. - These lesions often exhibit a subtle **annular or reticulated pattern**. *Usually affects exposed areas of body* - As its name suggests ("actinic" referring to light), this variant of lichen planus preferentially affects **sun-exposed areas** such as the face, neck, and dorsal hands. - This distribution distinguishes it from classic lichen planus, which can occur anywhere but often affects the flexor surfaces of the wrists, ankles, and oral mucosa. [Practice more Dermatology PYQs on OnCourse]

Q: In which part of the body are lesions of Kaposi sarcoma most commonly seen?

Lower extremities. ***Lower extremities*** - Kaposi sarcoma lesions most frequently appear on the **skin of the lower extremities**, especially the feet and ankles. - This predilection is thought to be due to increased **venous stasis** or other local factors. *Upper extremities* - While Kaposi sarcoma can affect the upper extremities, it is a **less common primary site** compared to the lower limbs. - Lesions here are more likely to appear as the disease **progresses or disseminates**. *Torso* - Kaposi sarcoma lesions can occur on the torso, particularly on the **trunk**, but it is not the most common initial presentation. - Visceral involvement of the **gastrointestinal tract** and lungs can often present without skin lesions on the torso. *Head and neck* - Lesions of Kaposi sarcoma can appear on the head and neck, especially on the **face and oral cavity**, particularly in classic Kaposi sarcoma or in individuals with advanced immunosuppression. - However, this is still **less frequent** than involvement of the lower extremities. [Practice more Dermatology PYQs on OnCourse]

19 Previous Year Questions with Answers & Explanations

Questions

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

HLA-Cw6 is associated with

Which area is typically not involved in a chickenpox rash?

Which of the following statements about actinic lichen planus is false?

In which part of the body are lesions of Kaposi sarcoma most commonly seen?

Most common flexural site for atopic dermatitis -

Which of the following statements about Bowen's disease is correct?

Which of the following statements is true regarding pemphigus vulgaris?

In which of the following conditions is phototherapy, specifically ultraviolet light therapy, useful for treatment?

Q10

Acanthosis nigricans is characterized by all of the following except?

NEET-PG 2015 - Dermatology NEET-PG Practice Questions and MCQs

Question 1: Phrynoderma is primarily associated with a deficiency of which of the following?

A. Essential fatty acid
B. Vitamin A (Correct Answer)
C. Vitamin D
D. Niacin

Explanation: ***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.

Question 2: HLA-Cw6 is associated with

A. Behcet's disease
B. Pemphigus vulgaris
C. Psoriasis vulgaris (Correct Answer)
D. Myasthenia gravis

Explanation: ***Psoriasis vulgaris*** - **HLA-Cw6** is the **strongest genetic risk factor** associated with an increased susceptibility to psoriasis vulgaris, particularly early-onset forms. - Its presence is linked to a more severe and widespread presentation of the disease. *Myasthenia gravis* - This autoimmune disorder is primarily associated with **HLA-DR3** and **HLA-B8**, and autoantibodies against the acetylcholine receptor. - While other HLA alleles may be involved, **HLA-Cw6** is not a primary or strong genetic association for myasthenia gravis. *Behcet's disease* - **HLA-B51** is the most significant genetic association with Behcet's disease, particularly in populations of Middle Eastern and East Asian descent. - Symptoms include **recurrent oral and genital ulcers**, **uveitis**, and skin lesions. *Pemphigus vulgaris* - This autoimmune blistering disease is strongly associated with **HLA-DR4** and **HLA-DRw6**, especially in individuals of Jewish descent. - It involves autoantibodies targeting **desmoglein 1 and 3**, leading to acantholysis within the epidermis.

Question 3: Which area is typically not involved in a chickenpox rash?

A. Trunk
B. Axilla
C. Back
D. Palms and soles (Correct Answer)

Explanation: ***Palms and soles*** - The chickenpox rash, caused by the **varicella-zoster virus**, typically spares the palms and soles. - Chickenpox exhibits a characteristic **centripetal distribution** (center-predominant), with lesions most numerous on the trunk and progressively fewer on the extremities. - **Sparing of palms and soles** is a classic differentiating feature from other viral exanthems like hand-foot-and-mouth disease. *Trunk* - The **trunk** is usually the **most heavily involved area** in a chickenpox rash, with lesions often appearing first and being most numerous here. - This is the hallmark of the characteristic **centripetal distribution** of the rash. *Axilla* - The **axilla** is a common site for chickenpox lesions due to its location on the trunk and the presence of **warm, moist skin folds** that can favor lesion development. - The rash tends to be widespread, making secondary sites like the axilla commonly involved. *Back* - The **back** is a major part of the trunk and is therefore extensively involved in a chickenpox rash. - The rash often starts on the trunk and spreads outwards, ensuring significant involvement of the back.

Question 4: Which of the following statements about actinic lichen planus is false?

A. Associated with severe pruritus (Correct Answer)
B. Violaceous brown papules
C. Usually affects exposed areas of body
D. Autoimmune etiology

Explanation: ***Associated with severe pruritus*** - While other forms of lichen planus, especially the typical cutaneous type, are often associated with **severe pruritus**, actinic lichen planus is typically characterized by **mild or absent pruritus**. - Its presentation is often more focused on pigmentary changes and papules in sun-exposed areas rather than intense itching. *Autoimmune etiology* - **Lichen planus**, including its actinic variant, is recognized as an **autoimmune disease**. - It involves a **T-cell-mediated immune response** against basal keratinocytes. *Violaceous brown papules* - Actinic lichen planus commonly presents with **violaceous, brown, or hyperpigmented papules and plaques**. - These lesions often exhibit a subtle **annular or reticulated pattern**. *Usually affects exposed areas of body* - As its name suggests ("actinic" referring to light), this variant of lichen planus preferentially affects **sun-exposed areas** such as the face, neck, and dorsal hands. - This distribution distinguishes it from classic lichen planus, which can occur anywhere but often affects the flexor surfaces of the wrists, ankles, and oral mucosa.

Question 5: In which part of the body are lesions of Kaposi sarcoma most commonly seen?

A. Upper extremities
B. Lower extremities (Correct Answer)
C. Torso
D. Head and neck

Explanation: ***Lower extremities*** - Kaposi sarcoma lesions most frequently appear on the **skin of the lower extremities**, especially the feet and ankles. - This predilection is thought to be due to increased **venous stasis** or other local factors. *Upper extremities* - While Kaposi sarcoma can affect the upper extremities, it is a **less common primary site** compared to the lower limbs. - Lesions here are more likely to appear as the disease **progresses or disseminates**. *Torso* - Kaposi sarcoma lesions can occur on the torso, particularly on the **trunk**, but it is not the most common initial presentation. - Visceral involvement of the **gastrointestinal tract** and lungs can often present without skin lesions on the torso. *Head and neck* - Lesions of Kaposi sarcoma can appear on the head and neck, especially on the **face and oral cavity**, particularly in classic Kaposi sarcoma or in individuals with advanced immunosuppression. - However, this is still **less frequent** than involvement of the lower extremities.

Question 6: Most common flexural site for atopic dermatitis -

A. Popliteal fossa
B. Elbow crease (Correct Answer)
C. Scalp
D. Trunk

Explanation: ***Elbow crease*** - The **antecubital fossa** (elbow crease) and **popliteal fossa** (knee crease) are the **two most characteristic flexural sites** for atopic dermatitis in children and adults. - Both sites are **equally common** and represent classic presentations of flexural eczema. - The constant rubbing, friction, and moisture retention in these areas contribute to skin irritation and the characteristic **lichenification** seen in atopic dermatitis. - In the context of this question asking for "most common," both antecubital and popliteal fossae are considered the primary flexural sites. *Popliteal fossa* - The **popliteal fossa** (behind the knee) is equally as common as the antecubital fossa and is a classic flexural site for atopic dermatitis. - It shares the same pathophysiological mechanisms and clinical presentation as the elbow crease. - Both antecubital and popliteal fossae are mentioned together in standard dermatology texts as the hallmark flexural sites. *Scalp* - While the scalp can be affected by atopic dermatitis, especially in **infants** (as **seborrheic dermatitis** or cradle cap), it is **not a flexural site**. - Scalp involvement typically presents as scaling and erythema, rather than the lichenified plaques characteristic of flexural eczema. *Trunk* - The trunk can be affected by atopic dermatitis with diffuse patches or widespread xerosis, but it is **not a flexural site**. - Flexural areas (skin folds) are the characteristic locations for atopic dermatitis in the flexural pattern.

Question 7: Which of the following statements about Bowen's disease is correct?

A. Chronic sun exposure is a known risk factor.
B. It is more common in fair-skinned individuals.
C. There is a link between HSV infection and Bowen's disease.
D. It is a form of squamous cell carcinoma in situ. (Correct Answer)

Explanation: ***It is a form of squamous cell carcinoma in situ.*** - **Bowen's disease** is, by definition, **squamous cell carcinoma in situ (SCC in situ)**. - It is characterized by full-thickness epidermal atypia of keratinocytes **without invasion through the basement membrane**. - This statement is **definitional** and represents the fundamental nature of what Bowen's disease is, making it the **best answer** among the options. *Chronic sun exposure is a known risk factor.* - This statement is **medically accurate**. Chronic UV exposure is indeed a well-established risk factor for Bowen's disease. - However, this describes a **risk factor** rather than defining what the condition is. - Other risk factors include **arsenic exposure**, **ionizing radiation**, **immunosuppression**, and **HPV infection** (particularly in anogenital sites). - While true, this is not as fundamental as the definitional statement. *It is more common in fair-skinned individuals.* - This statement is also **medically accurate**. Bowen's disease occurs more frequently in fair-skinned individuals (Fitzpatrick skin types I-II). - Fair skin provides less melanin protection against UV damage, increasing susceptibility to various forms of skin cancer including Bowen's disease. - However, this describes **epidemiology** rather than defining the condition itself. *There is a link between HSV infection and Bowen's disease.* - This statement is **incorrect**. There is **no established association** between Herpes Simplex Virus (HSV) and Bowen's disease. - **Human Papillomavirus (HPV)**, particularly high-risk types 16 and 18, is associated with Bowen's disease, especially in anogenital locations. - This represents a common confusion between HSV and HPV.

Question 8: Which of the following statements is true regarding pemphigus vulgaris?

A. It primarily affects the dermal-epidermal junction.
B. It is a subepidermal blistering disease.
C. It is an intraepidermal blistering disease. (Correct Answer)
D. Antibodies are formed against basement membrane proteins.

Explanation: ***It is an intraepidermal blistering disease.*** - **Pemphigus vulgaris** is characterized by the formation of blisters *within the epidermis* due to the loss of cell-to-cell adhesion between **keratinocytes**. - This **acantholysis** results from autoantibodies targeting **desmosomes**, specifically **desmoglein 1 and 3**. *It is a subepidermal blistering disease.* - This statement is incorrect as it describes conditions like **bullous pemphigoid** or **dermatitis herpetiformis**, where blisters form *below* the epidermis. - In pemphigus vulgaris, the separation occurs *above* the basement membrane within the epidermal layer. *It primarily affects the dermal-epidermal junction.* - This is characteristic of **bullous pemphigoid** or **epidermolysis bullosa acquisita**, where the primary pathology involves the separation at the interface between the dermis and epidermis. - Pemphigus vulgaris directly affects the adhesion *within* the epidermis itself. *Antibodies are formed against basement membrane proteins.* - This is characteristic of **bullous pemphigoid**, where autoantibodies target components of the **basement membrane zone**, such as **BP180** and **BP230**. - In pemphigus vulgaris, the autoantibodies target **desmogleins** on the surface of keratinocytes, not basement membrane proteins.

Question 9: In which of the following conditions is phototherapy, specifically ultraviolet light therapy, useful for treatment?

A. Psoriasis (Correct Answer)
B. Tinea corporis
C. Pemphigus
D. PMLE

Explanation: ***Psoriasis*** - **Phototherapy** (narrowband UVB, broadband UVB, or PUVA) is a **well-established first-line treatment** for **moderate-to-severe psoriasis**. - It works by **suppressing overactive immune cells** in the skin, reducing inflammation and decreasing keratinocyte proliferation. - **Direct therapeutic effect** on active psoriatic lesions makes this the primary indication for phototherapy in dermatology. *Tinea corporis* - **Tinea corporis** is a **superficial fungal infection** (dermatophytosis) of the skin. - Requires **antifungal medications** (topical azoles or oral terbinafine/griseofulvin) for treatment. - **Phototherapy has no antifungal activity** and is not used for this condition. *Pemphigus* - **Pemphigus** is an **autoimmune blistering disease** with intraepidermal acantholysis. - Treatment requires **systemic immunosuppression** (corticosteroids, rituximab, azathioprine). - **Phototherapy is not indicated** and could potentially worsen the condition. *PMLE* - **Polymorphous light eruption (PMLE)** is a common **photosensitivity disorder**. - While **prophylactic photohardening** (gradual controlled UV exposure) can be used to build tolerance **before sun exposure season**, this is a **preventative desensitization strategy**, not treatment of active disease. - Unlike psoriasis, phototherapy does **not treat active PMLE lesions** and can trigger flares if not done properly. - The primary approach for active PMLE is **sun avoidance, sun protection, and topical corticosteroids**.

Question 10: 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