Viral Skin Infections — MCQs

Viral Skin Infections Indian Medical PG Practice Questions and MCQs

Question 151: What is the commonest etiology of erythema multiforme?

A. Viral infections (Correct Answer)
B. Bacterial infections
C. Food allergies
D. Drug reactions

Explanation: **Explanation:** Erythema Multiforme (EM) is an acute, self-limiting Type IV hypersensitivity reaction characterized by the sudden onset of "target" or "iris" lesions. **1. Why Viral Infections are correct:** Infections are responsible for approximately 90% of EM cases. Among these, **Herpes Simplex Virus (HSV)** is the single most common trigger worldwide. HSV-1 is more frequently associated with EM than HSV-2. The pathogenesis involves the transport of viral DNA fragments to distant skin sites by circulating mononuclear cells, triggering a T-cell mediated immune response against keratinocytes. **2. Why other options are incorrect:** * **Bacterial infections:** While *Mycoplasma pneumoniae* is a significant cause (especially in children and cases with mucosal involvement), it is less common than viral etiologies. * **Food allergies:** These typically present as urticaria or anaphylaxis; they are not recognized triggers for the specific pathophysiology of EM. * **Drug reactions:** While drugs (like NSAIDs, sulfonamides, and anticonvulsants) can cause EM, they are much more strongly associated with **Stevens-Johnson Syndrome (SJS)** and **Toxic Epidermal Necrolysis (TEN)**. In clinical practice, if EM is triggered by a drug, it is often termed "EM Major." **Clinical Pearls for NEET-PG:** * **Target Lesion:** Consists of three zones—a central dusky/purpuric area (sometimes a vesicle), a pale edematous ring, and an outer erythematous halo. * **EM Minor vs. Major:** EM Minor involves minimal or no mucosal involvement; EM Major involves at least two mucosal surfaces. * **Recurrent EM:** Almost always associated with recurrent HSV infection. Prophylactic Acyclovir is the treatment of choice for these patients.

Question 152: A female presents with multiple small, pink, umbilicated papules on the face. What is the most likely diagnosis?

A. Acne vulgaris
B. Molluscum contagiosum (Correct Answer)
C. HPV
D. Herpes simplex

Explanation: ***Molluscum contagiosum*** - This condition, caused by a **poxvirus**, classically presents as multiple, discrete, small (2-5 mm), dome-shaped, pink or skin-colored papules with central **umbilication**. - It is a common, benign skin infection that spreads through direct contact or fomites and is frequently seen in children, sexually active adults, and immunocompromised individuals. *Herpes simplex* - Herpes simplex virus infection typically manifests as clusters of painful **vesicles** (small blisters) on an erythematous base, which later ulcerate and crust over. - The primary lesions are not solid papules and lack the characteristic central umbilication seen in molluscum. *HPV* - Human Papillomavirus (HPV) causes warts (verrucae), which are typically rough, hyperkeratotic papules (**verruca vulgaris**) or flat-topped papules (**verruca plana**). - Warts do not characteristically present with the smooth surface and central depression seen in molluscum contagiosum. *Acne vulgaris* - Acne is a disorder of the pilosebaceous unit, presenting with a variety of lesions including **comedones** (blackheads and whiteheads), inflammatory papules, and pustules. - Acne lesions are not umbilicated and are often associated with follicular inflammation and sebum production.

Question 153: A Tzanck smear prepared from a vesicle shows multinucleated giant cells. What is the diagnosis?

A. HSV (Correct Answer)
B. EBV
C. HIV
D. HPV

Explanation: ***HSV*** - The Tzanck smear is a rapid cytological test used to detect the viral cytopathic effects seen in vesicles caused by the *Herpesviridae* family, including **Herpes Simplex Virus (HSV)** and **Varicella-Zoster Virus (VZV)**. - The finding of **multinucleated giant cells** (also called **Tzanck cells**) formed by the fusion of infected keratinocytes is highly characteristic of herpetic infections. - **Important note**: The Tzanck smear **cannot distinguish between HSV and VZV** as both produce identical cytopathic effects. However, among the given options, **only HSV** is from the Herpesviridae family that causes vesicular lesions with this classic finding. - Clinical context (location, distribution, patient age) and confirmatory tests like **PCR** or **viral culture** are needed to differentiate HSV from VZV definitively. *HIV* - **HIV** (Human Immunodeficiency Virus) is diagnosed through blood tests, such as fourth-generation antigen/antibody screens or **PCR** for viral load. - The Tzanck smear is a test for vesicular dermatoses and **does not** play a role in the diagnosis of HIV infection. - HIV does not cause vesicles with multinucleated giant cells. *HPV* - **HPV** (Human Papillomavirus) causes warts and condylomas, which are diagnosed histologically showing characteristic **koilocytes** (squamous cells with perinuclear halos). - HPV lesions are **papular or verrucous**, not vesicular, and therefore would not yield multinucleated giant cells on Tzanck smear. - HPV does not belong to the Herpesviridae family. *EBV* - **EBV** (Epstein-Barr Virus) primarily causes Infectious Mononucleosis and is diagnosed using serological tests, such as the **Monospot test** (detecting heterophile antibodies) or EBV-specific antibodies. - EBV is **not associated with vesicular eruptions** and does not produce Tzanck-positive lesions. - EBV belongs to the Herpesviridae family but manifests systemically rather than with characteristic skin vesicles.

Question 154: A female patient presents to the OPD with complaints of recurrent lesions on lips, which is associated with fever. Which of the following is the characteristic feature seen in Tzanck smear?

A. Acantholytic cells
B. Henderson-Paterson bodies
C. Multinucleated giant cells (Correct Answer)
D. Owl eye appearance

Explanation: ***Multinucleated giant cells*** - Tzanck smear is a rapid diagnostic test for vesiculobullous lesions - In **Herpes Simplex Virus (HSV)** infection, the characteristic finding is **multinucleated giant cells** with nuclear molding (ballooning degeneration) - The clinical presentation of recurrent lip lesions with fever is classic for HSV-1 (herpes labialis) - Tzanck smear shows acantholysis and multinucleated keratinocytes *Acantholytic cells* - These are seen in **pemphigus vulgaris** (autoimmune blistering disorder) - Not characteristic of viral infections like HSV *Henderson-Paterson bodies* - These are intracytoplasmic inclusion bodies seen in **molluscum contagiosum** - Appear as eosinophilic structures (molluscum bodies) - Not seen in HSV infection *Owl eye appearance* - This describes large intranuclear inclusions seen in **Cytomegalovirus (CMV)** infection - Not characteristic of HSV infection

Question 155: A patient presented with multiple painful blisters on an erythematous base along a dermatome on the trunk as shown in the image. What is the diagnosis?

A. Herpes simplex
B. Herpes zoster (Correct Answer)
C. Molluscum contagiosum
D. Chicken pox

Explanation: ***Herpes zoster*** - This diagnosis is indicated by the classic presentation of a **painful, unilateral vesicular eruption** on an erythematous base, which is confined to a single **dermatome**. - It is caused by the **reactivation** of the latent **varicella-zoster virus (VZV)** from the dorsal root ganglia, which previously caused chickenpox. *Herpes simplex* - Herpes simplex virus (HSV) typically causes vesicular lesions grouped around the **orolabial** (HSV-1) or **genital** (HSV-2) regions, not in a dermatomal pattern on the trunk. - While it can cause a widespread eruption (eczema herpeticum), it does not characteristically follow a single nerve distribution like herpes zoster. *Molluscum contagiosum* - This condition presents as discrete, flesh-colored, **dome-shaped papules** with central **umbilication**, not as painful vesicles on an erythematous base. - It is caused by a **poxvirus**, and the lesions are typically scattered and not confined to a dermatome. *Chicken pox* - Chickenpox (primary VZV infection) presents as a **generalized, diffuse vesicular rash** that affects the entire body, rather than being limited to a single dermatome. - The rash appears in successive crops, resulting in lesions at **various stages of development** (papules, vesicles, and crusted lesions) simultaneously.

Question 156: A patient presents with painful ulcer in the mouth and a past history of recurrent vesicular lesions in the genitalia. Bedside test findings are shown. What is the most appropriate drug for management?

A. Ceftriaxone
B. Azithromycin
C. Penicillin
D. Acyclovir (Correct Answer)

Explanation: ***Correct: Acyclovir*** - The clinical history of recurrent painful oral and genital vesicular lesions, combined with the **Tzanck smear** finding of **multinucleated giant cells** (as shown in the image), is classic for **Herpes Simplex Virus (HSV)** infection. - **Acyclovir** is a guanosine analog antiviral drug that inhibits viral DNA polymerase, making it the first-line treatment for HSV and Varicella-Zoster Virus (VZV) infections. *Incorrect: Penicillin* - **Penicillin** is an antibiotic used to treat bacterial infections, most notably **syphilis**, which is caused by the spirochete *Treponema pallidum*. - Syphilis typically presents with a single, **painless chancre**, not recurrent painful vesicles, and penicillin has no efficacy against viral pathogens like HSV. *Incorrect: Ceftriaxone* - **Ceftriaxone** is a third-generation cephalosporin antibiotic, primarily used for bacterial infections such as **gonorrhea** and meningitis. - It is ineffective for treating viral infections, and the clinical presentation does not align with the purulent discharge characteristic of gonorrhea. *Incorrect: Azithromycin* - **Azithromycin** is a macrolide antibiotic effective against bacteria that can cause genital ulcers, such as **Haemophilus ducreyi** (causing **Chancroid**) and *Chlamydia trachomatis*. - While Chancroid causes painful ulcers, it does not typically present with a vesicular stage or the recurrent pattern seen in this case, nor would it show multinucleated giant cells on a smear.

Question 157: Identify the lesion shown in the image:

A. Herpes Zoster (Correct Answer)
B. Varicella
C. Impetigo
D. Contact Dermatitis

Explanation: ***Herpes Zoster (Shingles)*** - The image displays a characteristic **unilateral rash with vesicles and crusts** distributed along a **dermatome** on the child's face, specifically presenting as a pattern that follows the distribution of a **nerve root**, which is pathognomonic for **herpes zoster**. - This condition is caused by the **reactivation of the varicella-zoster virus (VZV)**, the same virus that causes chickenpox, remaining dormant in sensory ganglia. *Varicella (Chickenpox)* - Varicella typically presents as a **generalized rash** with lesions in various stages of development (macules, papules, vesicles, crusts) scattered across the entire body, not confined to a specific dermatome. - While caused by VZV, it is the **primary infection**, rather than reactivation, and does not exhibit a unilateral, dermatomal distribution. *Impetigo* - Impetigo is a **superficial bacterial skin infection** characterized by **honey-colored crusts** often preceded by small vesicles or bullae, but it does not typically follow a dermatomal pattern. - It usually occurs in areas of skin trauma or abrasions and is common around the nose and mouth. *Contact Dermatitis* - Contact dermatitis is an **inflammatory skin reaction** caused by contact with an allergen or irritant, resulting in redness, itching, and sometimes vesicles. - The distribution of contact dermatitis would typically correlate with the area of contact with the offending substance, not a specific nerve pathway.

Question 158: Identify the lesions given in the image:

A. Chickenpox (Correct Answer)
B. Measles
C. Rubella
D. Erythema infectiosum

Explanation: These options are generated based on the image only, as no options are provided in the input. ***Chickenpox*** - The image displays a rash characterized by **vesicles** and **crusted lesions** in various stages of healing, which is a hallmark of chickenpox (**varicella**). - The widespread distribution over the limbs and trunk, along with the polymorphic appearance of lesions, is typical for **Varicella-zoster virus infection**. *Measles* - Measles presents as a **maculopapular rash** that typically starts on the face and spreads downwards, often coalescing. - It does not typically involve the vesicular or crusted lesions seen in the image. *Rubella* - Rubella causes a **fine, pinkish-red rash** that is less prominent and generally fades more quickly than measles. - The lesions are usually discrete macules and do not progress to vesicles or crusts. *Erythema infectiosum* - This condition (also known as **Fifth Disease**) typically presents with a distinctive "slapped cheek" rash on the face, followed by a **lacy, reticular rash** on the trunk and limbs. - It does not produce vesicular lesions as depicted in the image.

Question 159: The following image shows:

A. Filiform Warts
B. Myrmecia (Correct Answer)
C. Epidermodysplasia verruciformis
D. Verruca vulgaris

Explanation: ***Myrmecia*** - The image shows a **plantar wart** (verruca plantaris) with a characteristic deep, solitary growth pattern and **central white core** visible after superficial paring, which is typical of **Myrmecia**, a type of plantar wart caused by HPV-1. - Myrmecia often appears as a **single, deep lesion** on the sole of the foot, distinguishable from mosaic warts which are flatter and multiple. *Filiform Warts* - **Filiform warts** are slender, finger-like projections found typically on the face, especially around the mouth and eyes, and are not seen on the sole of the foot as depicted. - They tend to be **flesh-colored** and project outwards rather than having a deep, endophytic growth pattern. *Epidermodysplasia verruciformis* - This is a rare, inherited genetic disorder characterized by **widespread, flat, wart-like lesions** and reddish-brown plaques, often resembling pityriasis versicolor, and is associated with a high risk of skin cancer. - The lesions seen in the image are localized and do not exhibit the broad, flat, widespread appearance typical of epidermodysplasia verruciformis. *Verruca vulgaris* - **Verruca vulgaris** (common warts) are typically common on the hands and fingers, presenting as raised, rough, **dome-shaped papules** with pinpoint black dots (thrombosed capillaries). - While they can occur anywhere, the morphology in the image, particularly the deep, endophitic growth with a central white core after paring, is more characteristic of a Myrmecia plantar wart than a typical verruca vulgaris.

Question 160: What is the causative agent for the lesion on penis shown below?

A. HPV (Correct Answer)
B. Treponema pallidum
C. EBV
D. KSHV

Explanation: ***HPV*** - The image shows **condylomata acuminata** (genital warts), which are raised, exophytic, **cauliflower-like** lesions characteristic of **Human Papillomavirus** infection. - These **verrucous** growths on the penis are typically caused by **HPV types 6 and 11**, which are low-risk, non-oncogenic strains. *Treponema pallidum* - This organism causes **condylomata lata** in secondary syphilis, which are **flat, broad, moist** lesions, not the raised exophytic lesions shown. - **Condylomata lata** have a characteristic **flat-topped** appearance with a grayish base, distinctly different from the verrucous morphology seen here. *EBV* - **Epstein-Barr virus** is associated with **infectious mononucleosis** and certain malignancies like **Burkitt lymphoma** and nasopharyngeal carcinoma. - EBV does not cause **genital warts** or any proliferative penile lesions of this morphology. *KSHV* - **Kaposi's Sarcoma-associated Herpesvirus** (HHV-8) causes **Kaposi's sarcoma**, which presents as **purple, red, or brown** vascular lesions. - Kaposi's sarcoma lesions are typically **flat macules** progressing to **nodular tumors**, not cauliflower-like genital warts.

Practice by Chapter

Herpes Simplex Virus Infections

Practice Questions

Varicella-Zoster Virus Infections

Practice Questions

Human Papillomavirus Infections

Practice Questions

Molluscum Contagiosum

Practice Questions

Viral Exanthems

Practice Questions

Hand, Foot, and Mouth Disease

Practice Questions

Orf and Milker's Nodule

Practice Questions

Cytomegalovirus Cutaneous Manifestations

Practice Questions

Epstein-Barr Virus Manifestations

Practice Questions

Poxvirus Infections

Practice Questions

HIV-Related Dermatoses

Practice Questions

Viral Infections in Immunocompromised Hosts

Practice Questions

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