Viral Skin Infections Practice Questions

Q: Myrmecia warts are a type of which wart?

Plantar wart. ***Plantar wart*** - **Myrmecia warts** are a specific subtype of **plantar warts**, characterized by their deep, endophytic growth into the sole of the foot. - They are caused by **HPV type 1** and named for their "ant-like" appearance with visible black dots (thrombosed capillaries). - They are often painful, especially with pressure, and can have a distinct translucent core with surrounding callused skin. *Plane wart* - **Plane warts** (verruca plana or **flat warts**) are a different type of wart entirely. - They are typically small, smooth, and flesh-colored papules that often appear in clusters on the face, hands, or shins. - They are superficial and flat, unlike the deep endophytic growth pattern of myrmecia warts. *Palmar wart* - **Palmar warts** are similar to plantar warts in appearance and histology but occur specifically on the **palms of the hands**. - While they share some characteristics with plantar warts, "myrmecia" specifically refers to the deep, painful warts found on the plantar surface of the foot. *Verrucous wart* - **Verrucous wart** is a general descriptive term referring to the rough, cauliflower-like surface often seen on common warts (verruca vulgaris). - While plantar warts can have a verrucous surface, "myrmecia wart" describes a more specific clinical and histological pattern within the plantar wart category.

Q: Multinucleated giant cell on Tzanck smear is not seen in?

Molluscum contagiosum. **Molluscum contagiosum** - Tzanck smear typically reveals **Henderson-Paterson bodies**, which are large eosinophilic intracytoplasmic inclusions within epithelial cells. - **Multinucleated giant cells** are not characteristic findings in lesions caused by the molluscum contagiosum virus (a poxvirus). *Herpes simplex* - Tzanck smear often shows **multinucleated giant cells** and **acantholytic cells**, which are specific cytopathic effects of HSV. - The presence of these cells helps in the rapid diagnosis of **herpes simplex viral infections**. *Varicella* - Similar to herpes simplex, **varicella-zoster virus (VZV)** infection also produces **multinucleated giant cells** on Tzanck smear. - These cells are a hallmark of **herpesvirus infections**, indicating viral cytopathic effects in epithelial cells. *Herpes zoster* - Herpes zoster, caused by the **reactivation of VZV**, also presents with **multinucleated giant cells** on Tzanck smear. - This finding aids in confirming the diagnosis of **shingles**, distinguishing it from other vesicular rashes.

Q: Pityriasis rosea is caused by?

HHV 6 & 7. ***HHV 6 & 7*** - Pityriasis rosea is strongly associated with the reactivation of **Human Herpesvirus 6 (HHV-6)** and **Human Herpesvirus 7 (HHV-7)**, particularly HHV-7. - While the exact pathogenic mechanism is not fully understood, these viruses are consistently found in lesions and blood samples of affected individuals. *HHV 3 & 4* - **HHV-3** is the **varicella-zoster virus (VZV)**, which causes chickenpox and shingles. - **HHV-4** is the **Epstein-Barr virus (EBV)**, primarily known for causing infectious mononucleosis. Neither is associated with pityriasis rosea. *HHV 4 & 5* - **HHV-4 (EBV)** causes infectious mononucleosis and is linked to certain cancers. - **HHV-5** is the **cytomegalovirus (CMV)**, which can cause mononucleosis-like syndrome or congenital infections. Neither is implicated in pityriasis rosea. *Autoimmune etiology* - While some autoimmune conditions can present with skin rashes, pityriasis rosea is generally considered to have a **viral etiology**, not an autoimmune one. - There is no consistent evidence to suggest immune system dysfunction as the primary cause of pityriasis rosea.

Q: Which pattern suggests secondary syphilis rather than pityriasis rosea?

Palmoplantar involvement. ***Palmoplantar involvement*** - **Secondary syphilis** characteristically presents with a rash that affects the **palms and soles**, a distribution that is rare in most other dermatological conditions, including pityriasis rosea. - This specific finding is a crucial diagnostic clue differentiating it from a wide range of other skin eruptions. *Christmas tree distribution* - The "Christmas tree" pattern, characterized by oval lesions following the **Langer's lines** on the trunk, is a classic presentation of **pityriasis rosea**. - This linear orientation is not typical for the rash of secondary syphilis. *Collarette scaling* - **Collarette scaling**, where fine scales are present just inside the periphery of a lesion, is a common feature of the individual lesions in **pityriasis rosea**. - While some scaling can be seen in syphilis, the distinctive collarette pattern is more indicative of pityriasis rosea. *Herald patch presence* - The appearance of a **herald patch** (or mother patch) — a single, larger, oval lesion that precedes the generalized rash — is a pathognomonic sign of **pityriasis rosea**. - No such precursor lesion is typically found in secondary syphilis.

Q: A 25-year-old male presents with a cluster of vesicles along the dermatome on his chest and back. He complains of burning pain in the same area. What is the most likely diagnosis?

Herpes zoster. ***Herpes zoster*** - The classic presentation of **vesicular rash along a dermatome** with **burning pain** is highly characteristic of herpes zoster (shingles). - This condition is caused by the **reactivation of the varicella-zoster virus (VZV)**, which lies dormant in sensory ganglia. *Contact dermatitis* - This condition typically presents as an **itchy, erythematous rash** that appears after contact with an allergen or irritant. - While vesicles can be present, the rash is usually not strictly confined to a single dermatome and **burning pain is less common** than itching. *Herpes simplex* - Herpes simplex virus (HSV) typically causes **localized clusters of vesicles** on mucosal surfaces (e.g., oral, genital) or skin. - It does not usually present with a **dermatomal distribution** on the trunk as described in the vignette. *Impetigo* - Impetigo is a **bacterial skin infection** characterized by **honey-crusted lesions** or pustules. - While it can involve vesicles, it does not follow a **dermatomal pattern** and is caused by bacteria, not a viral reactivation.

Q: Which of the following sexually transmitted infections is most likely to present with vesicular lesions that ulcerate?

Genital herpes. ***Genital herpes*** - Caused by the **herpes simplex virus (HSV)**, it typically manifests as clusters of **painful vesicles** on an erythematous base. - These vesicles subsequently **ulcerate**, producing characteristic shallow, often painful sores. *Syphilis* - Primarily presents as a **painless chancre** (a single, firm ulcer) in its primary stage, not vesicular lesions. - Vesicular lesions are not a typical presentation of any stage of syphilis. *Chancroid* - Characterized by one or more **painful, soft ulcers with ragged, undermined borders** and a grayish base. - It does not present with an initial vesicular stage. *Lymphogranuloma venereum* - Initial lesion is often a **small, painless papule or a shallow ulcer** that often goes unnoticed. - The most prominent feature is usually painful **inguinal lymphadenopathy** (buboes), rather than vesicular eruptions.

Q: How does herpes zoster typically present in immunocompetent adults?

Unilateral dermatomal rash. ***Correct: Unilateral dermatomal rash*** - Herpes zoster, commonly known as **shingles**, characteristically presents as a **painful, blistering rash** limited to a single dermatome on one side of the body. - This **unilateral distribution** follows the path of the affected sensory nerve root where the **varicella-zoster virus (VZV)** has reactivated. - This is the hallmark presentation in **immunocompetent adults**. *Incorrect: Bilateral dermatomal rash* - **Bilateral involvement** in herpes zoster is rare and typically suggests a **compromised immune system** rather than an immunocompetent adult. - A symmetrical rash would point away from the typical **dermatomal distribution** of VZV reactivation. *Incorrect: Vesicular rash on the face* - While herpes zoster can affect the face (e.g., **herpes zoster ophthalmicus** affecting the trigeminal nerve), the presentation is still **unilateral** and restricted to a specific dermatome. - The rash is not simply "on the face" but follows the distribution of one of the branches of the **trigeminal nerve**. - This option is too vague and doesn't specify the key **unilateral dermatomal** characteristic. *Incorrect: Pustular rash on the extremities* - The primary lesions of herpes zoster are typically **vesicles** (fluid-filled blisters), which can progress to pustules (pus-filled) but are not initially pustular. - The rash is confined to a **dermatome**, not diffusely spread across the extremities, which would suggest other conditions like **disseminated herpes simplex** or **bacterial skin infections**.

Q: A 30-year-old woman is diagnosed with genital herpes simplex virus infection by PCR analysis. Which type of lesion is most characteristic of this infection?

Vesicular. ***Vesicular*** - **Herpes simplex virus (HSV)** infections typically begin with the formation of painful, clustered **vesicles** (small, fluid-filled blisters) on an erythematous base. - These vesicles are characteristic of the primary stage of a herpetic outbreak before they rupture to form ulcers. *Pustular* - **Pustules** are elevated lesions filled with pus, often associated with bacterial infections or certain inflammatory conditions like acne. - While secondary bacterial infections can occur in HSV lesions, pustules are not the primary or most characteristic presentation of an uncomplicated HSV outbreak. *Maculopapular* - **Maculopapular rashes** consist of both flat, discolored lesions (**macules**) and raised, solid lesions (**papules**), commonly seen in viral exanthems or drug reactions. - This morphology is not typical for the localized, vesicular presentation of herpes simplex virus. *Erosive* - **Erosions** are superficial skin defects resulting from the loss of the epidermis, often occurring *after* vesicles rupture. - While genital herpes lesions eventually become erosive ulcers, the most characteristic *initial* lesion formed by the virus itself is the vesicle, which then *progresses* to an erosion.

Q: A 60-year-old man presents with a painful, vesicular rash in a dermatomal distribution on his right thorax. What is the most likely diagnosis?

Herpes zoster. ***Herpes zoster*** - The classic presentation of **painful, vesicular rash** in a **dermatomal distribution** is highly indicative of **herpes zoster**, also known as shingles. - This condition is caused by the reactivation of the **varicella-zoster virus (VZV)**, which lies dormant in sensory ganglia after a primary chickenpox infection. *Herpes simplex* - While herpes simplex causes **vesicular lesions**, they typically occur in localized clusters (e.g., oral or genital) and do not follow a **dermatomal pattern**. - Recurrent outbreaks are common, but the rash is generally less extensive and painful than in zoster. *Contact dermatitis* - **Contact dermatitis** is an inflammatory skin condition caused by exposure to irritants or allergens, resulting in an **erythematous, pruritic rash**, sometimes with vesicles. - However, it does not typically present with a **dermatomal distribution** and the pain is usually less prominent than the itching. *Impetigo* - **Impetigo** is a bacterial skin infection characterized by **honey-crusted lesions** and superficial blisters, commonly seen in children. - It is not typically painful, rarely follows a **dermatomal pattern**, and is not initially vesicular in the same way as zoster.

Question 1

Myrmecia warts are a type of which wart?

Accepted Answer

Plantar wart

Answer

Plane wart

Answer

Palmar wart

Answer

Verrucous wart

Question 2

Multinucleated giant cell on Tzanck smear is not seen in?

Accepted Answer

Molluscum contagiosum

Answer

Herpes simplex

Answer

Varicella

Answer

Herpes zoster

Question 3

Pityriasis rosea is caused by?

Accepted Answer

HHV 6 & 7

Answer

HHV 3 & 4

Answer

HHV 4 & 5

Answer

Autoimmune etiology

Question 4

Which pattern suggests secondary syphilis rather than pityriasis rosea?

Accepted Answer

Palmoplantar involvement

Answer

Christmas tree distribution

Answer

Collarette scaling

Answer

Herald patch presence

Question 5

A 40-year-old man with HIV (CD4 350) presents with multiple flesh-colored papules on face, some with central umbilication. He works as a preschool teacher. Most appropriate management is:

Accepted Answer

No treatment needed

Answer

Topical imiquimod

Answer

Immediate cryotherapy

Answer

Leave of absence until resolution

Question 6

A 25-year-old male presents with a cluster of vesicles along the dermatome on his chest and back. He complains of burning pain in the same area. What is the most likely diagnosis?

Accepted Answer

Herpes zoster

Answer

Contact dermatitis

Answer

Herpes simplex

Answer

Impetigo

Question 7

Which of the following sexually transmitted infections is most likely to present with vesicular lesions that ulcerate?

Accepted Answer

Genital herpes

Answer

Syphilis

Answer

Chancroid

Answer

Lymphogranuloma venereum

Question 8

How does herpes zoster typically present in immunocompetent adults?

Accepted Answer

Unilateral dermatomal rash

Answer

Bilateral dermatomal rash

Answer

Vesicular rash on the face

Answer

Pustular rash on the extremities

Question 9

A 30-year-old woman is diagnosed with genital herpes simplex virus infection by PCR analysis. Which type of lesion is most characteristic of this infection?

Accepted Answer

Vesicular

Answer

Pustular

Answer

Maculopapular

Answer

Erosive

Question 10

A 60-year-old man presents with a painful, vesicular rash in a dermatomal distribution on his right thorax. What is the most likely diagnosis?

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Contact dermatitis

Answer

Impetigo

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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