Viral Skin Infections — MCQs

Viral Skin Infections Indian Medical PG Practice Questions and MCQs

Question 181: Slapped cheek appearance is associated with which of the following?

A. Herpes zoster
B. Parvovirus B19 infection (Correct Answer)
C. Molluscum contagiosum
D. Kaposi sarcoma

Explanation: ***Parvovirus B19 infection*** - **Parvovirus B19** infection, also known as Fifth Disease or **Erythema Infectiosum**, classically presents with a **slapped cheek rash** on the face. - This characteristic facial rash is usually followed by a **lacy, reticular rash** on the trunk and extremities. *Herpes zoster* - **Herpes zoster** (shingles) presents as a painful, vesicular rash that follows a **dermatomal distribution**. - It does not cause a **slapped cheek appearance**; its rash is typically unilateral and confined to a single dermatome. *Molluscum contagiosum* - **Molluscum contagiosum** is characterized by small, flesh-colored, **umbilicated papules** with a central dimple. - These lesions can occur anywhere on the body but do not produce a diffuse facial rash like the **slapped cheek appearance**. *Kaposi sarcoma* - **Kaposi sarcoma** is a vascular tumor that manifests as **purple, brown, or reddish skin lesions**, often seen in immunocompromised individuals. - It is not associated with a **widespread facial rash** or the characteristic distribution of a slapped cheek appearance.

Question 182: A young man presented with painful vesicular lesions distributed along a dermatomal pattern on one side of his body. What is the likely diagnosis?

A. Lymphangioma circumscriptum
B. Molluscum contagiosum
C. Herpes simplex
D. Herpes Zoster (Correct Answer)

Explanation: ***Herpes Zoster*** - This condition is characterized by a **unilateral rash** that respects the **dermatomal distribution**, meaning it follows the path of a single nerve. - The lesions are typically **painful vesicles** and crusts, often associated with a burning sensation due to reactivation of the **varicella-zoster virus** (chickenpox virus). *Lymphangioma circumscriptum* - This is a rare **lymphatic malformation** presenting as clusters of **vesicles** or papules, often described as 'frog spawn' or 'tapioca pudding' in appearance. - While it can be painful, it usually does not follow a dermatomal pattern and is a congenital condition, not an acute viral eruption. *Molluscum contagiosum* - This is a viral skin infection producing small, firm, **umbilicated papules** that are typically flesh-colored or pearly. - While contagious, these lesions are generally **asymptomatic** and do not present with the acute pain, blistering, or dermatomal distribution characteristic of herpes zoster. *Herpes simplex* - This infection causes localized clusters of painful **vesicles** on an erythematous base, most commonly around the mouth (cold sores) or genitals. - Unlike herpes zoster, herpes simplex lesions typically recur in the same small area and do **not follow a dermatomal distribution**.

Question 183: Pleomorphic rash is a feature of:

A. Smallpox
B. Erythema subitum
C. Erythema infectiosum
D. Chickenpox (Correct Answer)

Explanation: ***Chickenpox*** - A **pleomorphic rash** in chickenpox means that lesions in different stages of development (macules, papules, vesicles, scabs) are present simultaneously in the same body area. - This characteristic presentation is a key diagnostic feature, differentiating it from smallpox where lesions typically appear in synchronized stages. *Smallpox* - The rash in smallpox tends to be **monomorphic**, meaning all lesions in a given area are at the same stage of development. - Smallpox lesions are typically *deep-seated*, firm, and progress slowly over several days. *Erythema subitum* - Also known as **roseola infantum**, this condition typically presents with a high fever followed by a **maculopapular rash** that appears as the fever breaks. - The rash is not pleomorphic and usually consists of small, discrete, rose-pink spots. *Erythema infectiosum* - Also known as **fifth disease**, it is characterized by a "slapped cheek" rash on the face, followed by a **lacelike or reticular rash** on the trunk and extremities. - The rash is not pleomorphic; its appearance is distinct and usually fades and reappears over several weeks.

Question 184: A child presents with grouped vesicles on the lips. What is the bedside investigation that you would like to do?

A. Wood's lamp
B. Slit skin smear
C. Tzanck smear (Correct Answer)
D. KOH

Explanation: ***Tzanck smear*** - A **Tzanck smear** is a rapid bedside test that can identify **multinucleated giant cells**, which are seen in herpes simplex virus infections. - The presence of **grouped vesicles on the lips** is highly suggestive of **herpes labialis** (HSV-1), which is primarily a **clinical diagnosis**. - Among the options provided, Tzanck smear is the only relevant bedside investigation, though it has **limited sensitivity and specificity** and **cannot distinguish between HSV and VZV**. - In modern practice, **PCR or direct immunofluorescence** are preferred when laboratory confirmation is needed, but Tzanck smear remains a low-cost option in resource-limited settings. *Wood's lamp* - A Wood's lamp uses **ultraviolet light** to detect certain fungal or bacterial infections by revealing characteristic fluorescence. - It is useful for conditions like **tinea capitis** (green fluorescence) and **erythrasma** (coral-red fluorescence), but has no role in diagnosing viral vesicular lesions. *Slit skin smear* - A **slit skin smear** is used to detect **acid-fast bacilli** in the diagnosis of **leprosy**. - It is not indicated for vesicular lesions and is irrelevant to herpes simplex infection. *KOH* - A **KOH (potassium hydroxide) mount** is used to diagnose **fungal infections** by dissolving keratinocytes and revealing fungal hyphae or spores. - It has no utility in diagnosing viral infections such as herpes simplex.

Question 185: Pseudo koebner's sign is seen in

A. Inverse psoriasis
B. Warts (Correct Answer)
C. Psoriasis
D. Lichen planus

Explanation: ***Warts*** - The **pseudo-Koebner phenomenon** refers to the appearance of new lesions at sites of trauma due to **viral inoculation** rather than an isomorphic response of a pre-existing dermatosis. - **Warts** (verruca vulgaris) caused by **human papillomavirus (HPV)** classically demonstrate pseudo-Koebner phenomenon, where the virus is inoculated into traumatized or abraded skin, leading to new wart formation along the trauma line. - Similarly, **molluscum contagiosum** can also show pseudo-Koebner phenomenon through viral seeding at trauma sites. *Psoriasis* - Psoriasis exhibits the **true Koebner phenomenon** (isomorphic response), not pseudo-Koebner. - In true Koebner, pre-existing psoriatic disease manifests as new psoriatic lesions at sites of trauma due to immune-mediated mechanisms. - This is fundamentally different from viral inoculation seen in pseudo-Koebner. *Lichen planus* - Lichen planus also demonstrates **true Koebner phenomenon**, where new lichen planus lesions appear at trauma sites. - This represents an isomorphic immune response, not viral spread, and therefore is not pseudo-Koebner phenomenon. *Inverse psoriasis* - Inverse psoriasis affects **intertriginous areas** (skin folds) and does not typically manifest Koebner or pseudo-Koebner phenomena. - The smooth, erythematous patches in flexural areas are less prone to the superficial trauma needed to elicit these responses.

Question 186: What is the diagnosis of an umbilicated, pearly white, asymptomatic skin lesion?

A. EBV
B. HSV
C. Molluscum contagiosum (Correct Answer)
D. None of the options

Explanation: ***Molluscum contagiosum*** - This **viral skin infection** typically presents with **multiple, small (2-5 mm), firm, pearly, dome-shaped papules** that have a **central umbilication**. - The lesions are usually **asymptomatic**, as described, though they can occasionally be itchy or inflamed. - Caused by a **poxvirus** and is highly contagious through direct contact. *EBV* - **Epstein-Barr Virus (EBV)** is primarily associated with **infectious mononucleosis**, which presents with fever, sore throat, and lymphadenopathy, not umbilicated skin lesions. - EBV can cause oral hairy leukoplakia in immunocompromised individuals, which is a white lesion, but it is **not pearly, umbilicated, or dome-shaped**. *HSV* - **Herpes Simplex Virus (HSV)** causes lesions that are typically **grouped vesicles on an erythematous base** that evolve into erosions or ulcers. - HSV lesions are often **painful or itchy** and **do not appear as pearly, umbilicated papules**. *None of the options* - This is incorrect because **Molluscum contagiosum** perfectly matches the clinical description of umbilicated, pearly white, asymptomatic skin lesions. - The classic **central umbilication** is the pathognomonic feature that distinguishes molluscum from other viral skin infections.

Question 187: Which of the following types of wart is treated by local application of podophyllin?

A. All of the options
B. Plantar wart
C. Verruca wart
D. Genital wart (Correct Answer)

Explanation: ***Genital wart*** - **Podophyllin** is an antimitotic agent that is commonly used for the topical treatment of **genital warts (condyloma acuminata)**. - Its mechanism involves arresting cell division in metaphase, leading to **necrosis of the wart tissue**. *All of the options* - While podophyllin is effective for some warts, it is not universally recommended for all types due to potential side effects and varying efficacy. - Other wart types, such as **plantar warts** and **verruca vulgaris**, often require different treatment modalities like salicylic acid, cryotherapy, or surgical excision. *Plantar wart* - **Plantar warts** are typically located on the soles of the feet and are often treated with **salicylic acid**, cryotherapy, or laser therapy, as they can be resistant to topical podophyllin. - The thick stratum corneum on the soles of the feet can limit the penetration of podophyllin, making it less effective for these warts. *Verruca wart* - The term "**verruca wart**" is general and usually refers to **verruca vulgaris** (common warts), which are often found on hands and fingers. - Treatment for common warts typically includes **cryotherapy**, salicylic acid preparations, or duct tape occlusion, rather than podophyllin, which can cause significant irritation on non-genital skin.

Question 188: Herpetic Whitlow is seen in

A. Bone
B. Tongue
C. Fingers (Correct Answer)
D. Lymph nodes

Explanation: ***Fingers*** - **Herpetic whitlow** is a painful infection caused by the **herpes simplex virus (HSV)**, predominantly affecting the fingers or toes. - It often presents with **vesicular lesions** and **erythema** on the digits, commonly occurring in healthcare workers or children with oral herpes. *Bone* - HSV infection of the bone is **extremely rare** and would typically manifest as osteomyelitis, not herpetic whitlow. - Herpetic whitlow primarily involves the **skin and subcutaneous tissues**, not skeletal structures. *Tongue* - HSV can cause **oral herpes (cold sores)** on the tongue, gums, or other perioral areas, but this is distinct from herpetic whitlow. - **Herpetic whitlow** specifically refers to digital HSV infection. *Lymph nodes* - While regional **lymphadenopathy** can be a secondary symptom of herpetic whitlow due to immune response, the primary infection site is not the lymph nodes. - Lymph nodes are part of the immune system and **filter lymph**, not typically sites for primary viral skin lesions.

Question 189: Frei's test is used in diagnosing which of the following conditions?

A. Granuloma inguinale
B. Donovanosis
C. Lymphogranuloma venereum (Correct Answer)
D. Soft chancre

Explanation: ***Lymphogranuloma venereum*** - The **Frei test** is a historical skin test used to diagnose **lymphogranuloma venereum (LGV)**, which is caused by specific serovars (L1, L2, L3) of *Chlamydia trachomatis*. - It involves injecting antigen derived from LGV-infected material intradermally, looking for a delayed hypersensitivity reaction (papule ≥6 mm after 48-72 hours). - Though historically significant, the Frei test is now **obsolete** and replaced by more specific serological tests and nucleic acid amplification tests (NAATs). *Granuloma inguinale* - This condition, also known as **donovanosis**, is caused by *Klebsiella granulomatis*. - Diagnosis is typically made by identifying **Donovan bodies** (intracytoplasmic cysts containing gram-negative bacteria) on tissue smear or biopsy, NOT by the Frei test. *Donovanosis* - Another term for **granuloma inguinale**, caused by *Klebsiella granulomatis*. - Characterized by painless, progressive genital ulcers with a beefy-red granulomatous appearance. - Diagnosis relies on demonstration of Donovan bodies, not the Frei test. *Soft chancre* - This refers to **chancroid**, a sexually transmitted infection caused by *Haemophilus ducreyi*. - Characterized by painful genital ulcers and tender inguinal lymphadenopathy. - Diagnosed by bacterial culture or PCR, not the Frei test.

Question 190: Podophyllin was historically used as treatment of choice in

A. Plain warts
B. Condyloma acuminata (Correct Answer)
C. Condyloma lata
D. Plantar warts

Explanation: ***Condyloma acuminata*** - **Podophyllin** is a **cytotoxic agent** that inhibits cell division and was historically a common topical treatment for **genital warts (condyloma acuminata)**. - Its mechanism of action targets the rapidly dividing cells of the HPV-induced warts, leading to necrosis and shedding. *Plain warts* - Plain warts (verruca vulgaris) are typically self-limiting and are often treated with **salicylic acid**, cryotherapy, or electrocautery. - While podophyllin can be effective against certain kinds of warts, it was not the primary or historical treatment of choice for common plain warts. *Condyloma lata* - **Condyloma lata** are moist, flat, broad lesions associated with **secondary syphilis** and are highly infectious. - Treatment involves **penicillin** to cure the underlying syphilis infection, not topical podophyllin. *Plantar warts* - **Plantar warts** occur on the soles of the feet and are often covered by a callus, making them difficult to treat with superficial methods. - Treatment typically involves **salicylic acid**, cryotherapy, **surgical excision**, or laser therapy due to their tough nature, rather than podophyllin.

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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