Which type of ultraviolet radiation causes the most skin disorders?
Potato nose is seen in ?
Which of the following drugs is effective in the treatment of pityriasis versicolor?
Pathergy test is used for which condition?
What percentage of skin involvement is characteristic of erythroderma?
What is the treatment for granuloma inguinale?
A 15cm hyperpigmented macule on an adolescent male undergoes changes such as coarseness, growth of hair & acne. Diagnosis is?
What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
Scalp and face are involved in-
Dermatophytes affect -
NEET-PG 2013 - Dermatology NEET-PG Practice Questions and MCQs
Question 21: Which type of ultraviolet radiation causes the most skin disorders?
- A. UV-A
- B. UV-B (Correct Answer)
- C. UV-C
- D. None of the options
Explanation: ***UV-B*** - **UV-B radiation** is a major cause of **sunburn** and directly damages DNA, leading to most **skin cancers** (basal cell carcinoma, squamous cell carcinoma, and melanoma). - It plays a significant role in photoaging and the development of most **skin disorders** related to sun exposure. *UV-A* - **UV-A radiation** penetrates deeper into the skin than UV-B and is primarily associated with **photoaging**, producing wrinkles and fine lines. - While it contributes to skin cancer development, its direct role in DNA damage and sunburn is less than that of UV-B. *UV-C* - **UV-C radiation** is the most damaging type of UV light, but it is almost entirely **absorbed by the Earth's ozone layer** and does not reach the Earth's surface. - Therefore, it does not typically cause skin disorders in humans under natural conditions. *None of the options* - This option is incorrect because **UV-B radiation** is well-established as a primary cause of numerous skin disorders, including most skin cancers and sunburn.
Question 22: Potato nose is seen in ?
- A. Acne vulgaris
- B. Rhinosporoidosis
- C. Acne rosacea (Correct Answer)
- D. Lupus vulgaris
Explanation: ***Acne rosacea*** - **Potato nose**, also known as **rhinophyma**, is a severe manifestation of **acne rosacea**, characterized by thickened, red, and bumpy skin on the nose. - This condition results from **hyperplasia of sebaceous glands** and connective tissue in the nose, leading to its characteristic bulbous appearance. *Acne vulgaris* - This common skin condition is characterized by **comedones**, **papules**, **pustules**, and sometimes cysts, primarily on the face, chest, and back. - It does **not typically cause rhinophyma** or significant thickening of nasal skin. *Rhinosporoidosis* - This is a **chronic granulomatous fungal infection** affecting mucous membranes, particularly the nose. - While it can cause nasal polyps and masses, it does **not result in the sebaceous gland hyperplasia** and thickened skin characteristic of rhinophyma. *Lupus vulgaris* - Lupus vulgaris is a chronic and progressive form of **cutaneous tuberculosis**, often affecting the face. - It presents with **reddish-brown plaques** and nodules that can ulcerate and scar but does **not lead to the specific nasal hypertrophy** seen in rhinophyma.
Question 23: Which of the following drugs is effective in the treatment of pityriasis versicolor?
- A. Ketoconazole (Correct Answer)
- B. Metronidazole
- C. Griseofulvin
- D. Chloroquine
Explanation: ***Ketoconazole*** - **Ketoconazole** is an **azoles antifungal agent** effective against the *Malassezia* species, the causative agent of **pityriasis versicolor**. - It works by inhibiting the synthesis of **ergosterol**, a crucial component of the fungal cell membrane, leading to its disruption and fungal cell death. *Metronidazole* - **Metronidazole** is an **antibiotic** and **amoebicide** primarily used to treat bacterial and parasitic infections. - It has **no antifungal activity** and is thus ineffective against *Malassezia* or other fungal infections. *Griseofulvin* - **Griseofulvin** is an **oral antifungal drug** primarily used for **dermatophyte infections** of the skin, hair, and nails (e.g., tinea capitis, onychomycosis). - It is **ineffective against yeasts and molds**, including *Malassezia*, making it unsuitable for pityriasis versicolor. *Chloroquine* - **Chloroquine** is an **antimalarial drug** also used in the treatment of some autoimmune conditions like lupus erythematosus. - It possesses **no antifungal properties** and is not used to treat fungal infections of any kind.
Question 24: Pathergy test is used for which condition?
- A. Lichen planus
- B. Atopic dermatitis
- C. Behçet's syndrome (Correct Answer)
- D. Reiter's syndrome
Explanation: ***Behçet's syndrome*** - The **pathergy test** is a diagnostic test where a sterile needle is used to prick the skin, and a positive result (erythematous papule or pustule) indicates a hyperreactivity of the skin, common in **Behçet's syndrome**. - This syndrome is a **vasculitis** characterized by recurrent oral and genital ulcers, ocular inflammation, and skin lesions, where pathergy is a characteristic feature. *Lichen planus* - This is an **inflammatory dermatosis** affecting the skin, hair, nails, and mucous membranes, characterized by "6 P's": **Pruritic, Purple, Polygonal, Planar, Papules, and Plaques**. - The pathergy test is **not used** in the diagnosis of lichen planus. *Atopic dermatitis* - Also known as **eczema**, it is a chronic, relapsing inflammatory skin condition characterized by dry, itchy skin and often associated with a personal or family history of allergies, asthma, or allergic rhinitis. - Diagnosis is primarily clinical, focusing on characteristic skin lesions and symptoms, and the **pathergy test is not applicable**. *Reiter's syndrome* - Now known as **reactive arthritis**, this condition is an autoimmune disorder that develops in response to an infection elsewhere in the body, typically genitourinary or gastrointestinal. - It classically presents with **arthritis, urethritis, and conjunctivitis** (Can't see, can't pee, can't climb a tree), and the **pathergy test is not used** for its diagnosis.
Question 25: What percentage of skin involvement is characteristic of erythroderma?
- A. More than 90% (Correct Answer)
- B. Less than 30%
- C. 30% to 60%
- D. 60% to 70%
Explanation: ***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.
Question 26: What is the treatment for granuloma inguinale?
- A. Tetracycline
- B. Azithromycin (Correct Answer)
- C. Clarithromycin
- D. Streptomycin
Explanation: ***Azithromycin*** - **Azithromycin** is the recommended first-line treatment for **granuloma inguinale** (donovanosis) caused by *Klebsiella granulomatis*. - Current recommended regimens: **Azithromycin 1g orally once weekly** OR **500mg daily for at least 3 weeks** (until all lesions have completely healed). - Preferred due to excellent tissue penetration, good efficacy, and convenient dosing that improves patient compliance. *Tetracycline* - **Tetracycline** (500mg four times daily) was historically used but has been largely replaced by **doxycycline** (100mg twice daily) as the preferred tetracycline-class antibiotic. - While effective against *Klebsiella granulomatis*, it requires frequent dosing leading to poor adherence. - **Doxycycline** (not listed here) is actually considered a co-first-line option alongside azithromycin in current CDC guidelines. *Clarithromycin* - **Clarithromycin** is a macrolide antibiotic but is not a recommended first-line agent for granuloma inguinale. - Limited clinical data supports its use for this condition, and it is not included in standard treatment guidelines. - Azithromycin from the same macrolide class is preferred due to better-established efficacy. *Streptomycin* - **Streptomycin** is an aminoglycoside antibiotic primarily used for mycobacterial infections (e.g., tuberculosis, plague). - Not indicated for granuloma inguinale as *Klebsiella granulomatis* responds well to macrolides (azithromycin) and tetracyclines (doxycycline). - Requires parenteral administration and has significant toxicity concerns (ototoxicity, nephrotoxicity).
Question 27: A 15cm hyperpigmented macule on an adolescent male undergoes changes such as coarseness, growth of hair & acne. Diagnosis is?
- A. Melanocytic nevus
- B. Becker nevus (Correct Answer)
- C. Sebaceous nevus
- D. Sebaceous adenoma
Explanation: ***Becker nevus*** - A Becker nevus is a **hyperpigmented patch** that typically appears during adolescence in males, often on the shoulder or upper trunk. - It characteristically becomes **hairy (hypertrichosis)**, more coarse, and can develop acne within the lesion, particularly during puberty due to androgen sensitivity. *Melanocytic nevus* - While melanocytic nevi are hyperpigmented, they generally do not show the characteristic changes of **coarseness, significant hair growth, or acne** within the lesion during adolescence. - They are typically stable in size and texture after initial development, with changes raising concern for **melanoma**. *Sebaceous nevus* - A sebaceous nevus is a **congenital lesion** often appearing as a yellowish-orange, waxy, or bumpy patch, usually on the scalp or face. - It does not typically present as a large, flat hyperpigmented macule that develops hair and acne in adolescence; instead, it may become verrucous or develop tumors in adulthood. *Sebaceous adenoma* - A sebaceous adenoma is a **benign tumor** of the sebaceous glands, usually appearing as a small, solitary, flesh-colored to yellowish papule or nodule, especially on the face. - It is not typically seen as a large, hyperpigmented macule that grows hair and acne over a broad area, as described in the question.
Question 28: What is the most likely diagnosis for a 15 mm hyperpigmented lesion on the shoulder that is enlarging and has hair growing from it?
- A. Melanocytic nevus
- B. Becker nevus (Correct Answer)
- C. Sebaceous nevus
- D. Comedo nevus
Explanation: ***Correct: Becker nevus*** This diagnosis is supported by the description of a **hyperpigmented lesion** that is **enlarging** and has **hair growing from it**, typically appearing during adolescence or young adulthood. **Becker nevus** often presents as an **irregular, hyperpigmented patch**, usually on the shoulder or upper trunk, and is characteristically associated with **hypertrichosis** (increased terminal hair growth). The combination of location (shoulder), enlargement, and hair growth in a 15 mm lesion is classic for Becker nevus. *Incorrect: Melanocytic nevus* While **melanocytic nevi** are hyperpigmented, they typically do not continue to **enlarge significantly** after childhood and generally do not develop new onset **hypertrichosis** as a primary feature. The size (15 mm) and progressive growth combined with hair development are more characteristic of a Becker nevus than a common melanocytic nevus. *Incorrect: Sebaceous nevus* **Sebaceous nevi** are typically **yellow-orange to tan, waxy plaques**, often on the scalp or face, with a cobblestone or papillomatous texture. They are not primarily characterized by **hyperpigmentation** and terminal hair growth, but rather by sebaceous gland proliferation. *Incorrect: Comedo nevus* A **comedo nevus** presents as a linear or unilateral group of **dilated follicular openings** filled with keratinous material, resembling blackheads. It is not characterized by diffuse **hyperpigmentation** or the increased terminal hair growth described in this case.
Question 29: Scalp and face are involved in-
- A. Nodular scabies
- B. Infantile scabies (Correct Answer)
- C. Norwegian scabies
- D. Adult scabies
Explanation: ***Infantile scabies*** - In **infants** and young children, scabies can present with widespread lesions, often involving the **head, neck, face, palms, and soles**, unlike in adults. - The immune system in infants is less developed, leading to more generalized and severe manifestations. - This is the characteristic distribution pattern that distinguishes infantile scabies. *Nodular scabies* - Characterized by persistent red-brown **nodules**, typically located in the axillae, groin, and scrotum. - While a variant of scabies, it does not specifically involve the scalp and face as a primary distinguishing feature. - These nodules can persist even after treatment. *Norwegian scabies* - Also called **crusted scabies**, this severe form occurs in immunocompromised patients. - Characterized by **thick, crusted lesions** with millions of mites, highly contagious. - While it can involve extensive body areas including face in immunocompromised hosts, the typical presenting feature is thick crusts, not the predilection for scalp/face seen in infantile scabies. *Adult scabies* - In adults, scabies typically spares the **head and neck** area, affecting interdigital spaces, wrists, elbows, axillae, and groin. - Involvement of the face and scalp is rare in adults, unless they are immunocompromised. - This distribution pattern is the key differentiating feature from infantile scabies.
Question 30: Dermatophytes affect -
- A. Dermis of skin
- B. Keratin (Correct Answer)
- C. Stratum spongiosum
- D. Stratum basale
Explanation: ***Keratin*** - **Dermatophytes** are a group of fungi that have a unique ability to digest **keratin**, a protein found in **skin, hair, and nails**. - This characteristic allows them to colonize and thrive in these superficial tissues, causing infections like **tinea corporis** (ringworm) or **tinea pedis** (athlete's foot). *Dermis of skin* - The **dermis** is the layer of skin beneath the epidermis, rich in **collagen, elastin, blood vessels, and nerves**. - Dermatophytes do not typically invade the dermis; their infections are generally limited to the **stratum corneum** and other keratinized structures. *Stratum spongiosum* - **Stratum spongiosum** is a term sometimes used to describe an edematous (swollen) epidermis, often seen in **eczema** and **dermatitis**. - Dermatophytes do not target this specific architectural change in the epidermis but rather feed on the keratin present in the more superficial layers. *Stratum basal* - The **stratum basale** (also called stratum germinativum) is the deepest layer of the **epidermis**, responsible for cell division and producing new skin cells. - Dermatophytes primarily infect the **dead keratinized cells** of the stratum corneum rather than the metabolically active cells of the stratum basale.