NEET-PG 2015 — Dermatology
19 Previous Year Questions with Answers & Explanations
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?
In which part of the body are lesions of Kaposi sarcoma most commonly seen?
All of the following are premalignant conditions except which of the following?
What condition is suggested by eyelid papules and a hoarse cry in a child?
Which of the following statements about actinic lichen planus is false?
All of the following are part of the treatment of scabies except?
What do the Lines of Blaschko represent?
Most common flexural site for atopic dermatitis -
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: 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 5: All of the following are premalignant conditions except which of the following?
- A. Bowen's Disease
- B. Pyoderma Gangrenosum (Correct Answer)
- C. Xeroderma Pigmentosum
- D. Actinic Keratosis
Explanation: ***Pyoderma Gangrenosum*** - This is a **neutrophilic dermatosis** characterized by rapidly enlarging, painful ulcers with undermined, violaceous borders. It is an inflammatory condition, not premalignant. - While often associated with systemic diseases such as **inflammatory bowel disease** or **rheumatoid arthritis**, it does not inherently carry an increased risk of developing into skin cancer. *Bowen's Disease* - This is a form of **squamous cell carcinoma in situ**, meaning the cancerous cells are confined to the epidermis and have not yet invaded the dermis. - It is considered a **premalignant lesion** because it has the potential to progress to invasive squamous cell carcinoma if left untreated. *Actinic Keratosis* - These are **rough, scaly patches** on the skin caused by years of sun exposure, predominantly in fair-skinned individuals. - Actinic keratoses are considered **premalignant lesions** with a risk of transforming into invasive squamous cell carcinoma. *Xeroderma Pigmentosum* - This is a rare, **autosomal recessive genetic disorder** characterized by a defect in DNA repair mechanisms, specifically nucleotide excision repair. - Individuals with xeroderma pigmentosum have an extremely high risk of developing various **skin cancers** (basal cell carcinoma, squamous cell carcinoma, melanoma) at an early age due to their inability to repair UV-induced DNA damage.
Question 6: What condition is suggested by eyelid papules and a hoarse cry in a child?
- A. Croup
- B. Lipoid proteinosis (Correct Answer)
- C. Acrodermatitis enteropathica
- D. Congenital syphilis
Explanation: ***Lipoid proteinosis*** - This condition is characterized by **hoarseness from infancy** due to deposition in the vocal cords and characteristic **beaded papules on the eyelids** (moniliform blepharosis). - Also known as **Urbach-Wiethe disease**, it is a rare autosomal recessive disorder resulting from mutations in the **ECM1 gene**, leading to abnormal deposition of hyaline material in various tissues. *Croup* - Croup typically presents with a **barking cough** and **stridor**, often following a viral upper respiratory infection. - It does not cause eyelid papules or chronic hoarseness from infancy, but rather acute respiratory distress. *Acrodermatitis enteropathica* - This is a rare autosomal recessive disorder of **zinc malabsorption**, leading to a classic triad of **dermatitis**, **diarrhea**, and **alopecia**. - It does not involve eyelid papules or hoarseness as primary features. *Congenital syphilis* - Congenital syphilis can cause a wide range of manifestations, including skin rashes, bone abnormalities, and rhinitis ("snuffles"), but eyelid papules and chronic hoarseness are not typical presenting features. - Diagnosis is usually confirmed by serological tests for syphilis.
Question 7: 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 8: All of the following are part of the treatment of scabies except?
- A. Topical Permethrin
- B. Oral antihistamines
- C. Oral ivermectin
- D. Long term oral steroids (Correct Answer)
Explanation: ***Long term oral steroids*** - **Long-term oral steroids** are generally avoided in scabies treatment as they can **suppress the immune system**, potentially worsening the infestation. - While steroids might offer temporary relief from itching, they do not address the underlying parasitic cause and can lead to various **side effects** with prolonged use. *Topical Permethrin* - **Topical permethrin** 5% cream is a **first-line treatment** for scabies, highly effective against the *Sarcoptes scabiei* mite. - It is typically applied to the entire body from the neck down, left on for 8-14 hours, and then washed off. *Oral ivermectin* - **Oral ivermectin** is an alternative treatment, particularly useful for **crusted scabies**, widespread infestations, or in cases where topical treatments are difficult to administer. - It acts by disrupting the nervous system of the mites, leading to their death. *Oral antihistamines* - **Oral antihistamines** are used to manage the **intense pruritus** (itching) associated with scabies. - They do not kill the mites but provide symptomatic relief, improving patient comfort.
Question 9: What do the Lines of Blaschko represent?
- A. Patterns along lymphatics
- B. Patterns along blood vessels
- C. Patterns along nerves
- D. Patterns of cell migration (Correct Answer)
Explanation: ***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.
Question 10: 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.