Viral Skin Infections Practice Questions

Q: What diagnosis is suggested by the finding on the sole of this patient's foot?

Plantar wart. ***Plantar wart (Verruca plantaris)*** - The image shows a **hyperkeratotic lesion with central black dots** on the sole of the foot, which is pathognomonic for a **plantar wart** - Plantar warts are caused by **human papillomavirus (HPV)** infection, most commonly types 1, 2, and 4 - The characteristic **black dots represent thrombosed capillaries**, not necrosis - Key diagnostic features include **interruption of skin lines** across the lesion and **tenderness on lateral compression** (pinch test) - They occur on **pressure-bearing areas** of the foot and can be solitary or multiple (mosaic warts) *Chemical burn* - Chemical burns present with **erythema, blistering, or ulceration** with more diffuse or irregular borders - History of **chemical exposure** would be present, and the lesion lacks the characteristic black dots seen in plantar warts - The pattern and location don't fit typical chemical injury *Pemphigus* - Pemphigus is an **autoimmune blistering disease** presenting with **flaccid bullae** that rupture easily - It primarily affects **mucous membranes and flexural areas**, rarely presenting as a solitary hyperkeratotic lesion on the sole - The clinical presentation is completely different from the hyperkeratotic lesion with black dots shown *Radiation dermatitis* - Radiation dermatitis occurs after **therapeutic or accidental radiation exposure** - Presents with **erythema, desquamation, hyperpigmentation, or fibrosis** in the radiation field - Would not present as a discrete hyperkeratotic lesion with black dots, and the sole of the foot is an unusual site for radiation therapy

Q: Podophyllin was historically used as treatment of choice in

Condyloma acuminata. ***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.

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: Most common manifestation of HPV infection in children :

Common skin warts (verruca vulgaris). ***Common skin warts (verruca vulgaris)*** - **Verruca vulgaris**, or common skin warts, are the most frequent cutaneous manifestation of **human papillomavirus (HPV)** infection in children. - These warts are typically caused by **HPV types 2, 4, and 7** and are often found on the hands, fingers, and feet. - They account for the majority of HPV-related lesions in the pediatric population. *Condyloma acuminatum (genital warts)* - While **condyloma acuminatum** (genital warts) are caused by HPV (usually types 6 and 11), they are **much less common** in children compared to common skin warts. - In children, their presence may raise concerns about sexual abuse or vertical transmission from mother to child. - Common skin warts remain the predominant manifestation in the pediatric age group. *Sarcoma* - **Sarcomas** are malignant tumors of connective tissue and are not directly caused by HPV infection. - HPV is associated with **carcinomas** (epithelial cancers) like cervical, anal, and oropharyngeal cancers, but not sarcomas. *Osteoma* - An **osteoma** is a benign tumor composed of bone tissue, usually found on the skull or facial bones. - It is not associated with HPV infection and is typically a slow-growing, asymptomatic lesion.

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 of the following conditions is associated with autoinoculation, where lesions spread to other body sites through scratching or direct contact?

Papilloma. ***Papilloma*** - **Papillomas** (viral warts) caused by **human papillomavirus (HPV)** are the classic example of autoinoculation in dermatology. - The virus can spread from one body site to another through **scratching, shaving, or direct contact** with the lesion. - This is particularly common with common warts, plantar warts, and flat warts, which can seed adjacent skin areas through mechanical trauma. - Autoinoculation is a hallmark feature of **viral cutaneous infections**, especially HPV-related lesions. *Bullous pemphigoid* - **Bullous pemphigoid** is an autoimmune blistering disease caused by antibodies against basement membrane zone proteins (BP180 and BP230). - Blisters arise due to **internal autoimmune processes**, not mechanical spread or autoinoculation. - While scratching may rupture blisters, this does not cause new blisters to form at distant sites—the disease distribution is determined by the autoimmune process, not by mechanical seeding. *Leukoplakia* - **Leukoplakia** is characterized by white patches on mucous membranes that cannot be scraped off and are considered **precancerous**. - It is not associated with autoinoculation or the spread of lesions through scratching. - This is a dysplastic mucosal change, not an infectious or mechanically spreadable condition. *Ameloblastoma* - **Ameloblastoma** is a rare, benign, but locally aggressive tumor of odontogenic epithelial origin, occurring mainly in the **jaws**. - It is an internal tumor and has no association with skin lesions, scratching, or autoinoculation.

Q: A female patient presents with multiple sessile lesions on the vulva that do not bleed on touch. What is the most likely diagnosis?

Condyloma acuminata. ***Condyloma acuminata*** - **Condyloma acuminata**, also known as genital warts, are typically **sessile or pedunculated lesions** with a verrucous (cauliflower-like) appearance, commonly found on the vulva. - These lesions are caused by the **human papillomavirus (HPV)** and generally do not bleed on touch unless traumatized. *Molluscum* - **Molluscum contagiosum** presents as **dome-shaped, pearly papules** with a central umbilication, not sessile lesions. - The lesions are typically smaller and have a characteristic central dimple. *Herpes genitalis* - **Herpes genitalis** presents as painful **vesicles or ulcers** that often rupture and form crusts, not sessile lesions. - These lesions are typically accompanied by pain and itching. *Chancroid* - **Chancroid** is characterized by one or more **painful, soft chancres** with irregular, undermined borders and a grayish base that often bleeds easily. - Ulcers are the hallmark of chancroid, not sessile growths.

Q: In a case of recurrent genital herpes with >6 episodes per year, which prophylactic regimen is most appropriate?

Valacyclovir 500mg daily. ***Valacyclovir 500mg daily*** - **Valacyclovir 500mg once daily** is the most appropriate prophylactic regimen for frequent recurrent genital herpes (≥6 episodes/year) - **Once-daily dosing** significantly improves patient adherence compared to multiple daily doses, which is crucial for long-term suppressive therapy - **Higher bioavailability** than acyclovir (54% vs 15-20%), allowing for less frequent dosing - **CDC-recommended** suppressive therapy regimen with proven efficacy in reducing recurrence frequency by 70-80% - For patients with ≥10 episodes per year, the dose can be increased to **1g once daily** *Acyclovir 400mg BD* - This is a **valid alternative** CDC-recommended suppressive regimen - However, **twice-daily dosing** is less convenient for long-term prophylaxis compared to once-daily valacyclovir - **Lower bioavailability** requires more frequent dosing to maintain therapeutic levels - May be preferred in resource-limited settings due to lower cost *Famciclovir 250mg BD* - This is also a **valid CDC-recommended** suppressive therapy option - **Twice-daily dosing** reduces adherence compared to once-daily regimens - Generally considered a **second-line alternative** when acyclovir or valacyclovir are not tolerated - Effective but less commonly used as first-line suppressive therapy *Acyclovir 200mg 5 times daily* - This is an **acute episodic treatment** regimen for active outbreaks, not for suppressive prophylaxis - **Five times daily dosing** is impractical for long-term use and has poor adherence - Used for treating initial or recurrent episodes, typically for 5 days duration

Q: A patient with anogenital warts has not responded to conventional therapy after 3 months. Next best step is:

HIV testing. ### HIV testing - **Persistent, recalcitrant anogenital warts** that do not respond to conventional therapy after 3 months are a strong indicator of **immunocompromise** [1]. - **HIV infection** is a common cause of immunosuppression that can lead to treatment failure for anogenital warts [1]. *Switch to imiquimod* - While **imiquimod** is a topical treatment for anogenital warts, switching therapies without investigating the cause of treatment failure is not the initial best step. - The lack of response suggests an underlying issue rather than simply a need for a different treatment type. *Continue same treatment longer* - Continuing the same treatment when there has been **no response after 3 months** is unlikely to be effective and delays appropriate management. - This approach does not address the underlying reason for treatment failure. *Biopsy lesion* - While a **biopsy** can be important to confirm the diagnosis or rule out malignancy, it is typically considered after addressing potential underlying causes for treatment resistance, such as **immunocompromise**. - In this scenario, the primary concern is the lack of response to therapy, which points towards an immune system issue.

Question 1

What diagnosis is suggested by the finding on the sole of this patient's foot?

Accepted Answer

Plantar wart

Answer

Chemical burn

Answer

Pemphigus

Answer

Radiation dermatitis

Question 2

Podophyllin was historically used as treatment of choice in

Accepted Answer

Condyloma acuminata

Answer

Plain warts

Answer

Condyloma lata

Answer

Plantar warts

Question 3

Myrmecia warts are a type of which wart?

Accepted Answer

Plantar wart

Answer

Plane wart

Answer

Palmar wart

Answer

Verrucous wart

Question 4

Multinucleated giant cell on Tzanck smear is not seen in?

Accepted Answer

Molluscum contagiosum

Answer

Herpes simplex

Answer

Varicella

Answer

Herpes zoster

Question 5

Most common manifestation of HPV infection in children :

Accepted Answer

Common skin warts (verruca vulgaris)

Answer

Condyloma acuminatum (genital warts)

Answer

Sarcoma

Answer

Osteoma

Question 6

Pityriasis rosea is caused by?

Accepted Answer

HHV 6 & 7

Answer

HHV 3 & 4

Answer

HHV 4 & 5

Answer

Autoimmune etiology

Question 7

Which of the following conditions is associated with autoinoculation, where lesions spread to other body sites through scratching or direct contact?

Accepted Answer

Papilloma

Answer

Leukoplakia

Answer

Bullous pemphigoid

Answer

Ameloblastoma

Question 8

A female patient presents with multiple sessile lesions on the vulva that do not bleed on touch. What is the most likely diagnosis?

Accepted Answer

Condyloma acuminata

Answer

Molluscum

Answer

Herpes genitalis

Answer

Chancroid

Question 9

In a case of recurrent genital herpes with >6 episodes per year, which prophylactic regimen is most appropriate?

Accepted Answer

Valacyclovir 500mg daily

Answer

Acyclovir 400mg BD

Answer

Famciclovir 250mg BD

Answer

Acyclovir 200mg 5 times daily

Question 10

A patient with anogenital warts has not responded to conventional therapy after 3 months. Next best step is:

Accepted Answer

HIV testing

Answer

Switch to imiquimod

Answer

Continue same treatment longer

Answer

Biopsy lesion

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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