Viral Skin Infections Practice Questions

Q: What is the diagnosis in this patient with axillary lymphadenopathy?

Herpetic whitlow. ***Herpetic whitlow*** - A **viral infection** caused by **herpes simplex virus (HSV)** that presents with **grouped vesicles** on the finger, commonly causing **regional lymphadenopathy** in the axilla. - The **vesicular appearance** and associated **axillary lymph node enlargement** are characteristic of HSV infection, distinguishing it from bacterial causes. *Bacterial felon* - A **deep bacterial infection** of the **fingertip pulp space** that presents as a **painful, swollen fingertip** without vesicles. - Does **not typically cause axillary lymphadenopathy** and lacks the characteristic vesicular lesions seen in viral infections. *Erysipelas* - A **superficial bacterial infection** of the skin caused by **Streptococcus pyogenes** with **raised, erythematous borders**. - Primarily affects **facial areas** and lower extremities, not typically the fingers, and would not present with vesicular lesions. *Paronychia* - A **bacterial or fungal infection** of the **nail fold** presenting as **erythema and swelling** around the nail margin. - Does **not cause vesicular lesions** or significant **axillary lymphadenopathy** as it remains a localized superficial infection.

Q: Hairy leukoplakia is associated with all of the following EXCEPT?

Filiform to flat patch on lateral tongue. **Explanation:** Oral Hairy Leukoplakia (OHL) is a benign, white mucosal lesion primarily caused by the **Epstein-Barr Virus (EBV)**. It is a hallmark opportunistic infection, most commonly seen in patients with **AIDS** or severe immunosuppression. **Why Option A is the Correct Answer (The "Except"):** The description "Filiform to flat patch" is clinically inaccurate for OHL. OHL characteristically presents as **corrugated, vertically oriented white ridges** (resembling "hair" or a "shaggy" surface) that **cannot be scraped off**. While it classically occurs on the **lateral borders of the tongue**, the morphology is typically thick and corrugated rather than a simple flat patch or filiform projection. **Analysis of Other Options:** * **Option B (Bilateral appearance):** OHL is frequently bilateral and symmetrical along the lateral margins of the tongue, which helps distinguish it from other unilateral lesions like squamous cell carcinoma. * **Option C (Epstein Barr virus):** EBV is the definitive causative agent. The virus replicates within the epithelial cells of the tongue, leading to the characteristic hyperkeratosis. * **Option D (AIDS):** OHL is one of the most common oral manifestations of HIV/AIDS. Its presence is often considered a clinical marker of disease progression and a low CD4 count (usually <200 cells/mm³). **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis:** Unlike Oral Candidiasis, OHL **cannot be scraped off** with a tongue depressor. * **Histopathology:** Look for **"Balloon cells"** (koilocytosis-like changes) in the upper stratum spinosum and nuclear inclusions. * **Treatment:** Usually not required unless for cosmetic reasons; it often resolves with Highly Active Antiretroviral Therapy (HAART) or systemic antivirals like Acyclovir. * **Malignant Potential:** Unlike idiopathic leukoplakia, OHL has **zero** premalignant potential.

Q: What is the most common genital lesion observed in patients with HIV?

Herpes. **Explanation:** The correct answer is **Herpes (HSV-2)**. In patients living with HIV, **Herpes Simplex Virus (HSV)** is the most common cause of genital ulcer disease (GUD) worldwide [1]. There is a synergistic relationship between the two viruses: HIV-induced immunosuppression leads to more frequent, severe, and persistent herpetic outbreaks, while the open ulcers caused by HSV provide a portal of entry that increases the risk of HIV transmission and acquisition. **Analysis of Options:** * **B. Herpes (Correct):** Studies consistently show that HSV-2 is the most prevalent co-infection and the leading cause of genital lesions in HIV-positive individuals [1]. In advanced HIV, these lesions may become "chronic" (lasting >1 month), which is an AIDS-defining illness. * **A. Chlamydia:** While common as a cause of urethritis or cervicitis, it typically presents as a discharge rather than a visible external "genital lesion" (except for the rare Lymphogranuloma Venereum strain). * **C. Syphilis:** *Treponema pallidum* causes genital ulcers (chancre), and while its incidence is rising among HIV-positive populations, it remains less common than HSV [1]. * **D. Candida:** Candidiasis is a very common opportunistic fungal infection in HIV (especially oral thrush), and while it can cause balanitis or vulvovaginitis, it is not the most common cause of a primary genital lesion compared to HSV. **High-Yield Clinical Pearls for NEET-PG:** * **AIDS-Defining Condition:** A chronic herpetic ulcer (mucocutaneous) persisting for more than **1 month** is an AIDS-defining illness. * **Atypical Presentation:** In HIV patients, HSV may present as large, deep, "punched-out" necrotic ulcers or even hypertrophic/verrucous lesions that mimic malignancy. * **Treatment:** Acyclovir is the drug of choice, but higher doses or longer durations are often required. Be aware of **Acyclovir-resistant HSV** in non-responsive cases (treated with Foscarnet).

Q: What is the drug of choice for treating genital warts?

Podophyllin. **Explanation:** Genital warts (Condyloma acuminata) are caused by the **Human Papillomavirus (HPV)**, most commonly types 6 and 11. Unlike systemic viral infections, these are localized epidermal proliferations. **Podophyllin** (and its purified form, Podophyllotoxin) is a potent cytotoxic agent that acts as a mitotic inhibitor. It binds to tubulin, preventing mitotic spindle formation, which leads to cell death and the physical destruction of the wart tissue. It remains a standard provider-applied chemical treatment for external genital warts. **Analysis of Options:** * **Acyclovir (A):** This is an antiviral used specifically for DNA viruses of the **Herpes family** (HSV, VZV). It inhibits viral DNA polymerase but has no efficacy against HPV. * **Minocycline (C):** This is a tetracycline antibiotic used primarily for acne, rosacea, and certain bacterial infections. It has no antiviral properties. * **Interferon alpha (D):** While it has antiviral and immunomodulatory properties and can be used for refractory cases (intralesional), it is not the first-line drug of choice due to high cost, side effects, and lower clearance rates compared to topical destructive therapies. **Clinical Pearls for NEET-PG:** * **Imiquimod:** A high-yield alternative; it is an **immune response modifier** (TLR-7 agonist) used for patient-applied treatment. * **Trichloroacetic Acid (TCA):** The preferred chemical treatment for pregnant women with genital warts (Podophyllin is contraindicated in pregnancy). * **Histology:** Look for **Koilocytes** (cells with perinuclear halo and wrinkled "raisinoid" nuclei) on a Tzanck smear or biopsy. * **HPV 16 & 18:** These are high-risk types associated with cervical and anal carcinoma, whereas 6 and 11 are low-risk (benign warts).

Q: A 5-year-old child presents with raised, firm, flesh-colored nodules. Histopathological examination reveals characteristic findings. What is the most likely diagnosis?

Molluscum contagiosum. **Explanation:** **Molluscum Contagiosum (Correct Answer):** Molluscum contagiosum is a common viral infection caused by a **Poxvirus**. It typically presents in children as firm, flesh-colored, dome-shaped papules with a characteristic **central umbilication**. The histopathological hallmark is the presence of **Henderson-Paterson bodies** (large, eosinophilic intracytoplasmic inclusion bodies) within the keratinocytes, which displace the nucleus to the periphery. **Why other options are incorrect:** * **Myrmecia (A):** This refers to deep, painful palmoplantar warts caused by **HPV-1**. Histology shows large eosinophilic keratohyalin granules, but they lack the classic umbilication and specific inclusion bodies of Molluscum. * **Herpes Zoster (C) & Herpes Simplex (D):** Both are caused by the Herpesviridae family. Clinically, they present as **vesicles on an erythematous base** (not flesh-colored nodules). Histopathology reveals **multinucleated giant cells** (Tzanck smear positive) and Cowdry Type A intranuclear inclusions, rather than cytoplasmic inclusions. **NEET-PG High-Yield Pearls:** * **Etiology:** DNA Poxvirus (Molluscum Contagiosum Virus). * **Transmission:** Skin-to-skin contact; in adults, it is often considered an **STI** if found in the anogenital region. * **Histology:** Look for the "molluscum body" or **Henderson-Paterson body**. * **Clinical Sign:** Central umbilication (cheesy material can be expressed). * **Association:** Extensive or giant lesions in adults should prompt an **HIV screening**.

Q: The characteristic rash of chickenpox exhibits which of the following distribution patterns?

Centripetal distribution. **Explanation:** Chickenpox (Varicella), caused by the **Varicella-Zoster Virus (VZV)**, is characterized by a classic rash that follows a **centripetal distribution**. This means the lesions are most concentrated on the trunk (chest, back, and abdomen) and face, with relative sparing of the distal extremities (palms and soles). **Analysis of Options:** * **Centripetal distribution (Correct):** The rash typically begins on the trunk and spreads outward, but the density remains highest centrally. This is a hallmark diagnostic feature. * **Deep seated (Incorrect):** Varicella vesicles are superficial and thin-walled, often described as "dewdrops on a rose petal." Deep-seated, firm lesions are characteristic of Smallpox (Variola). * **Monomorphic (Incorrect):** Chickenpox is **pleomorphic**. This means lesions at various stages of development (macules, papules, vesicles, and crusts) are present simultaneously in the same anatomical area. Smallpox, conversely, is monomorphic. * **Umbilicated (Incorrect):** While some varicella vesicles may show slight central depression as they crust, "umbilication" is the classic descriptor for **Molluscum Contagiosum** or Smallpox. **NEET-PG High-Yield Pearls:** * **Incubation Period:** 10–21 days. * **Infectivity:** From 1–2 days before the rash appears until all lesions have crusted over. * **Tzanck Smear:** Shows **Multinucleated Giant Cells** (also seen in Herpes Simplex). * **Complications:** Secondary bacterial infection (most common in children) and Varicella pneumonia (most common/severe in adults). * **Smallpox vs. Chickenpox:** Smallpox is centrifugal (peripheral), monomorphic, and deep-seated; Chickenpox is centripetal (central), pleomorphic, and superficial.

Q: What is the most likely diagnosis?

Herpes zoster. ***Herpes zoster*** - Presents with characteristic **unilateral vesicles or ulcers** that follow a specific **dermatomal distribution**, commonly affecting the **trigeminal nerve** branches in oral cavity - The **painful, vesicular eruption** typically remains confined to one side and follows the anatomical nerve pathway, making it highly distinctive *Candidiasis* - Characterized by **white plaques** that can be wiped off, revealing an **erythematous base** underneath - Typically presents **bilaterally** and affects immunocompromised patients, diabetics, or those on antibiotics *Geographic tongue* - Features **map-like patches** with **red centers** and **white borders** on the **dorsal surface** of the tongue - This is a **benign condition** with migrating patterns that doesn't follow dermatomal distribution *Lichen planus* - Presents with **white reticular striae** (Wickham's striae) in a **lace-like pattern** on buccal mucosa - Typically affects **bilateral buccal mucosa** and doesn't follow unilateral dermatomal patterns

Q: Dew drops on rose petal appearance is seen in infection with which of the following?

Varicella zoster virus. **Explanation:** The classic clinical description **"dew drops on rose petal"** refers to the characteristic morphology of the primary rash in **Chickenpox**, caused by the **Varicella-Zoster Virus (VZV)**. 1. **Why Varicella-Zoster Virus is correct:** The rash typically begins as small, clear, thin-walled vesicles (the "dew drop") situated on an intensely erythematous, circular base (the "rose petal"). This appearance occurs because the virus causes intraepidermal acantholysis, leading to fluid accumulation. A hallmark of VZV is **pleomorphism**, where lesions at different stages of evolution (papules, vesicles, and crusts) are seen simultaneously in the same anatomical area. 2. **Why other options are incorrect:** * **Herpes genitalis (HSV-2):** While it also presents with vesicles on an erythematous base, these are typically **grouped (herpetiform)** and painful, rather than the scattered "dew drop" distribution seen in VZV. * **Candida:** Presents as bright red erythematous plaques with characteristic **satellite lesions** (pustules at the periphery), often in intertriginous areas. * **T. rubrum:** This is a dermatophyte causing Tinea corporis/cruris, characterized by **annular plaques** with central clearing and an active, scaly border. **High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** Used for rapid diagnosis of VZV and HSV; look for **Multinucleated Giant Cells** and Cowdry Type A inclusion bodies. * **Centripetal Distribution:** VZV rash starts on the trunk and spreads to the face and extremities (opposite of Smallpox). * **Ramsay Hunt Syndrome:** Reactivation of VZV in the geniculate ganglion, leading to facial palsy and vesicles in the external auditory canal.

Q: The pseudo-isomorphic phenomenon is seen in which of the following dermatological conditions?

Molluscum contagiosum. **Explanation:** The **pseudo-isomorphic phenomenon** (also known as the pseudo-Koebner phenomenon) refers to the spread of infectious lesions along a line of trauma, such as scratching or shaving. Unlike the true Koebner phenomenon, which involves an inflammatory response, this occurs due to **autoinoculation** of an infectious agent into the skin. **1. Why Molluscum Contagiosum is correct:** Molluscum contagiosum is caused by a **Poxvirus**. The virus replicates within the epidermis, and when a lesion is traumatized, the infectious viral particles are mechanically spread along the scratch mark, leading to a linear distribution of new umbilicated papules. This is a classic example of autoinoculation. **2. Why the other options are incorrect:** * **A, B, and C (Psoriasis, Lichen Planus, Vitiligo):** These conditions exhibit the **True Koebner Phenomenon (Isomorphic Phenomenon)**. In these cases, non-specific trauma (like a scratch) triggers the development of new lesions of a pre-existing non-infectious skin disease in previously healthy skin. They are mediated by inflammatory and immunological pathways rather than infection. **High-Yield Clinical Pearls for NEET-PG:** * **True Koebner Phenomenon:** Seen in Psoriasis (most common), Lichen Planus, and Vitiligo. * **Pseudo-Koebner Phenomenon:** Seen in Molluscum contagiosum, Verruca (Warts), and Impetigo. * **Reverse Koebner:** Disappearance of a lesion following trauma (e.g., Psoriasis). * **Wolf’s Isotopic Response:** Occurrence of a new skin disease at the exact site of a previously healed, unrelated skin disease (most commonly seen after Herpes Zoster). * **Molluscum Contagiosum Key Feature:** Presence of **Henderson-Paterson bodies** (intracytoplasmic inclusion bodies) on histopathology.

Question 1

What is the diagnosis in this patient with axillary lymphadenopathy?

Accepted Answer

Herpetic whitlow

Answer

Bacterial felon

Answer

Erysipelas

Answer

Paronychia

Question 2

Hairy leukoplakia is associated with all of the following EXCEPT?

Accepted Answer

Filiform to flat patch on lateral tongue

Answer

Bilateral appearance

Answer

Epstein Barr virus

Answer

AIDS

Question 3

What is the most common genital lesion observed in patients with HIV?

Accepted Answer

Herpes

Answer

Chlamydia

Answer

Syphilis

Answer

Candida

Question 4

A 35-year-old man has noted a small bump on his upper trunk for the past 6 weeks. On physical examination, there is a solitary, 0.4-cm, flesh-colored nodule on the upper trunk. The dome-shaped lesion is umbilicated, and a curd-like material can be expressed from the center. This material is smeared on a slide, and the Giemsa stain shows many pink, homogeneous, cytoplasmic inclusions. The lesion regresses over the next 2 months. Which of the following infectious agents most likely produced this lesion?

Accepted Answer

Molluscum contagiosum

Answer

Histoplasma capsulatum

Answer

Human papillomavirus

Answer

Staphylococcus aureus

Question 5

What is the drug of choice for treating genital warts?

Accepted Answer

Podophyllin

Answer

Acyclovir

Answer

Minocycline

Answer

Interferon alpha

Question 6

A 5-year-old child presents with raised, firm, flesh-colored nodules. Histopathological examination reveals characteristic findings. What is the most likely diagnosis?

Accepted Answer

Molluscum contagiosum

Answer

Myrmecia

Answer

Herpes zoster

Answer

Herpes simplex

Question 7

The characteristic rash of chickenpox exhibits which of the following distribution patterns?

Accepted Answer

Centripetal distribution

Answer

Deep seated

Answer

Monomorphic

Answer

Umbilicated

Question 8

What is the most likely diagnosis?

Accepted Answer

Herpes zoster

Answer

Candidiasis

Answer

Geographic tongue

Answer

Lichen planus

Question 9

Dew drops on rose petal appearance is seen in infection with which of the following?

Accepted Answer

Varicella zoster virus

Answer

Herpes genitalis

Answer

Candida

Answer

T. rubrum

Question 10

The pseudo-isomorphic phenomenon is seen in which of the following dermatological conditions?

Accepted Answer

Molluscum contagiosum

Answer

Psoriasis

Answer

Lichen planus

Answer

Vitiligo

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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