Viral Skin Infections Practice Questions

Q: What is the primary route of transmission for molluscum contagiosum in adults?

Sexual contact. ***Sexual contact*** - In adults, **molluscum contagiosum** is predominantly transmitted through **direct skin-to-skin contact**, especially during sexual activity. - The lesions are often found in the **genital**, **perineal**, and **lower abdominal areas** in sexually active individuals. *Fecal-oral route* - This route of transmission is associated with infections spread through contaminated food or water, such as **Hepatitis A** or **gastroenteritis**, not molluscum contagiosum. - Molluscum contagiosum is a **poxvirus** that infects the skin directly, and is not shed in feces. *Respiratory droplets* - Diseases like the **common cold**, **influenza**, and **COVID-19** are typically spread via respiratory droplets, which involve airborne transmission from coughing or sneezing. - Molluscum contagiosum is a **dermal infection** and is not transmitted through the air. *Vector-borne transmission* - Vector-borne diseases are transmitted by living organisms, such as **mosquitoes** (e.g., malaria, dengue) or **ticks** (e.g., Lyme disease). - Molluscum contagiosum has no known insect or animal vector involved in its transmission.

Q: A 30-year-old man with recurrent genital warts has undergone multiple treatments without success. Which of the following treatments would be most appropriate to try next?

Imiquimod cream. ***Imiquimod cream*** - **Imiquimod** is an **immune response modifier** that stimulates the production of **cytokines**, such as interferon-alpha, which has antiviral and antiproliferative effects, making it effective for persistent warts. - It is particularly useful for recurrent warts or those unresponsive to ablative therapies due to its mechanism of action targeting the underlying viral infection. *Electrocautery* - **Electrocautery** physically destroys the wart tissue using heat, which can be effective but carries risks of scarring and potential recurrence if not completely eradicated. - For recurrent warts, the underlying Human Papillomavirus (HPV) infection needs to be addressed, which ablative methods like electrocautery do not inherently do. *Podophyllin resin* - **Podophyllin resin** is a **cytotoxic agent** that inhibits cell division, leading to tissue necrosis; however, it can be irritating and is generally not recommended for extensive or recurrent lesions due to potential systemic absorption and toxicity. - Its mechanism primarily involves destroying the infected cells rather than stimulating a host immune response, which might be less effective for recurrent cases. *Liquid nitrogen cryotherapy* - **Liquid nitrogen cryotherapy** works by freezing and destroying the wart tissue, but it often requires multiple sessions and can be painful. - Similar to electrocautery, it is an ablative method that does not directly enhance the host's immune response to clear the Human Papillomavirus (HPV), making it less ideal for recurrent cases where host immunity might be a factor.

Q: A 25-year-old woman is diagnosed with first-episode genital herpes. Which clinical feature best predicts the likelihood of frequent recurrences?

HSV-2 versus HSV-1 etiology. ***HSV-2 versus HSV-1 etiology*** - **HSV-2 infections** are associated with significantly **higher recurrence rates** (typically 4-5 recurrences per year) compared to genital HSV-1 infections (approximately one recurrence every two years) [1]. - The **anatomical site** (genital vs. oral) and the **viral serotype** are key determinants of recurrence frequency [1]. *Severe primary episode* - While a severe primary episode may indicate a higher viral load or a less robust immune response, it does **not reliably predict the frequency of future recurrences**. - Its severity is more indicative of the **initial symptomatic presentation** rather than the long-term recurrence pattern [1]. *Presence of prodromal symptoms* - **Prodromal symptoms** (e.g., tingling, itching) precede a recurrence but **do not predict the likelihood or frequency** of subsequent recurrences. - They are an important patient cue for an impending outbreak, but not a prognostic factor for recurrence rate. *Duration of lesions >10 days* - The **duration of primary lesions** is characteristic of the initial infection's severity and the time taken for healing, but it does **not predict the frequency of future recurrences**. - Longer lesion duration may reflect a more widespread or intense initial viral shedding, rather than persistent viral activity over time.

Q: What is the characteristic microscopic finding in a Tzanck smear from a herpes lesion?

Multinucleated giant cells. ***Multinucleated giant cells*** - The presence of **multinucleated giant cells** (also called Tzanck cells or multinucleated keratinocytes) is the **most characteristic** cytological finding in a Tzanck smear from herpes simplex virus (HSV) or varicella-zoster virus (VZV) lesions. - These giant cells with **2-15 nuclei** form due to **viral-induced cell fusion (syncytia formation)** and are readily identified on routine staining. - This is the hallmark finding that makes Tzanck smear a useful rapid diagnostic test. *Intracellular inclusion bodies* - While **intranuclear inclusion bodies** (Cowdry type A inclusions) are indeed present in herpes infections, they are **less prominent** and require careful examination [1]. - These inclusions are **strictly intranuclear** (within the nucleus), appearing as eosinophilic inclusions surrounded by a clear halo [1]. - Although diagnostic when present, multinucleated giant cells are more readily identified and thus considered the characteristic finding on Tzanck smear. *Budding yeast cells* - **Budding yeast cells** are characteristic of fungal infections, most commonly *Candida* species. - They are typically seen in conditions like candidiasis, not viral infections such as herpes. *Clue cells* - **Clue cells** are epithelial cells covered with bacteria, specifically *Gardnerella vaginalis*, and are a hallmark of **bacterial vaginosis**. - They are not associated with viral vesicular lesions or herpes infections. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.

Q: A patient presents with painful vesicles as shown in the image. What is the diagnosis?

Herpes. ***Herpes*** - The image shows a cluster of **small, painful vesicles on an erythematous base**, which is highly characteristic of a herpes simplex virus (HSV) infection. - These lesions typically evolve into ulcers, crust over, and heal, and are often recurrent. *Chancroid* - Chancroid presents as **painful, soft chancres** (ulcers) with irregular, undermined borders and a gray or yellow base, often accompanied by **buboes** (enlarged, tender lymph nodes). - It does not typically manifest as clusters of small vesicles. *Syphilis* - Primary syphilis presents as a **painless chancre**—a single, firm, ulcerated lesion with a clean base and raised borders. - Secondary syphilis can cause a variety of skin manifestations, but not painful vesicles. *Candidiasis* - Cutaneous candidiasis usually appears as a **red, moist rash with satellite lesions** (smaller papules or pustules spreading from the main rash), often in skin folds. - While it can be inflammatory and itchy, it does not typically form discreet painful vesicles as seen in the image.

Q: A 7-year-old child presents to the dermatology clinic with multiple small, painless, flesh-colored papules on the trunk and arms that have been present for 3 months. The lesions are 2-4 mm in diameter, dome-shaped with a smooth surface, and several have a characteristic central umbilication. The child is otherwise healthy and immunocompetent. The lesions are not pruritic and there is no associated lymphadenopathy. On closer examination, a white, cheesy material can be expressed from the central depression of some lesions. What is the most likely diagnosis?

Molluscum contagiosum. ***Molluscum contagiosum*** - The classic presentation of **flesh-colored, dome-shaped papules** with **central umbilication** is pathognomonic for molluscum contagiosum. - The presence of a **white, cheesy material** that can be expressed from the central depression is characteristic of the viral core. *Trichodysplasia spinulosa* - This condition presents with **follicular papules** and **spiny projections**, primarily on the face, and is typically seen in **immunocompromised** individuals. - The description of **flesh-colored, dome-shaped papules** with **umbilication** does not fit the typical presentation of trichodysplasia spinulosa. *Condyloma acuminata* - These are **genital warts** caused by HPV, typically presenting as **verrucous** or **cauliflower-like lesions** on the anogenital region. - The description of **small, painless, flesh-colored papules** with **central umbilication** on the trunk and arms is inconsistent with condyloma acuminata. *Donovanosis* - Donovanosis, or **granuloma inguinale**, is a rare bacterial infection causing **ulcerative lesions** in the genital and perianal areas. - This diagnosis is highly unlikely given the child's age, rash location (trunk and arms), and the specific morphology of the lesions.

Q: A woman presents with lesions on the inner thighs and peri-anal region. They are nodular, 4-6 mm in size and appear pale. The histopathological image shows multiple intracytoplasmic inclusion bodies consistent with Henderson-Patterson bodies. The diagnosis is:

Molluscum contagiosum. ***Molluscum contagiosum*** - The clinical presentation of **nodular, pale lesions** in the inner thighs and peri-anal region, combined with histopathology showing **Henderson-Patterson bodies** (large eosinophilic intracytoplasmic inclusions), is pathognomonic for molluscum contagiosum. - Henderson-Patterson bodies represent viral factories within infected keratinocytes, a key diagnostic feature of this **poxvirus** infection. *Trichodysplasia spinulosa* - This condition is characterized by **follicular papules** with prominent keratin spines, typically occurring on the face, and is associated with the **Trichodysplasia spinulosa-associated polyomavirus**. - It does not present with Henderson-Patterson bodies or the typical nodular lesions seen in molluscum contagiosum. *Condyloma acuminata* - These are **genital warts** caused by the **human papillomavirus (HPV)**, presenting as verrucous or cauliflower-like growths. - Histologically, they show **koilocytic atypia** (vacuolated cells with nuclear abnormalities), not Henderson-Patterson bodies. *Donovanosis* - Also known as **granuloma inguinale**, this is a chronic, progressive, ulcerative granulomatous disease caused by **Klebsiella granulomatis**. - Histopathology reveals **Donovan bodies** (intracellular bacteria within macrophages), which are distinct from Henderson-Patterson bodies and the clinical presentation of nodular lesions.

Q: A 60-year-old patient presents with unilateral vesicular lesions in a dermatomal distribution on the torso. The lesions are painful and appeared over the past 2-3 days, progressing from erythematous patches to fluid-filled vesicles. The patient reports prodromal burning and tingling sensation in the affected area. Which of the following is the most likely diagnosis?

Herpes zoster infection. ***Herpes zoster infection*** - The patient's presentation of **unilateral vesicular lesions** in a **dermatomal distribution**, accompanied by severe pain and a **prodromal burning and tingling sensation**, is classic for herpes zoster (shingles). - Herpes zoster results from the **reactivation of latent varicella-zoster virus (VZV)** in a sensory ganglion, leading to painful rash along the affected nerve path. *Irritant contact dermatitis* - This condition involves inflammation due to direct contact with an irritating substance, often presenting with **eczematous lesions**, redness, itching, and sometimes vesicles. - However, it typically lacks the characteristic **dermatomal distribution** and severe neuropathic pain seen in herpes zoster. *Allergic contact dermatitis* - Allergic contact dermatitis is an immune-mediated reaction to an allergen, causing intensely pruritic, erythematous, and often **vesicular or bullous eruptions** that tend to spread beyond the initial contact area over time. - While it can cause vesicles, it does not follow a **dermatomal pattern** and is usually very itchy, rather than primarily painful and burning, with a distinct prodrome. *Herpes Simplex Infection* - Herpes simplex virus (HSV) infections also cause **vesicular lesions** but typically present as clusters of vesicles on an **erythematous base** in a localized area, often around the mouth (cold sores) or genitals. - Unlike herpes zoster, HSV lesions are usually **recurrent** in the same small area and typically do not exhibit a widespread, **unilateral dermatomal pattern** or the associated severe, persistent neuropathic pain.

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

Parvovirus B19 infection. ***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.

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

Herpes Zoster. ***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 1

What is the primary route of transmission for molluscum contagiosum in adults?

Accepted Answer

Sexual contact

Answer

Fecal-oral route

Answer

Respiratory droplets

Answer

Vector-borne transmission

Question 2

A 30-year-old man with recurrent genital warts has undergone multiple treatments without success. Which of the following treatments would be most appropriate to try next?

Accepted Answer

Imiquimod cream

Answer

Electrocautery

Answer

Podophyllin resin

Answer

Liquid nitrogen cryotherapy

Question 3

A 25-year-old woman is diagnosed with first-episode genital herpes. Which clinical feature best predicts the likelihood of frequent recurrences?

Accepted Answer

HSV-2 versus HSV-1 etiology

Answer

Severe primary episode

Answer

Presence of prodromal symptoms

Answer

Duration of lesions >10 days

Question 4

What is the characteristic microscopic finding in a Tzanck smear from a herpes lesion?

Accepted Answer

Multinucleated giant cells

Answer

Intracellular inclusion bodies

Answer

Budding yeast cells

Answer

Clue cells

Question 5

A patient presents with painful vesicles as shown in the image. What is the diagnosis?

Accepted Answer

Herpes

Answer

Chancroid

Answer

Syphilis

Answer

Candidiasis

Question 6

A 7-year-old child presents to the dermatology clinic with multiple small, painless, flesh-colored papules on the trunk and arms that have been present for 3 months. The lesions are 2-4 mm in diameter, dome-shaped with a smooth surface, and several have a characteristic central umbilication. The child is otherwise healthy and immunocompetent. The lesions are not pruritic and there is no associated lymphadenopathy. On closer examination, a white, cheesy material can be expressed from the central depression of some lesions.

What is the most likely diagnosis?

Accepted Answer

Molluscum contagiosum

Answer

Trichodysplasia spinulosa

Answer

Condyloma acuminata

Answer

Donovanosis

Question 7

A woman presents with lesions on the inner thighs and peri-anal region. They are nodular, 4-6 mm in size and appear pale. The histopathological image shows multiple intracytoplasmic inclusion bodies consistent with Henderson-Patterson bodies. The diagnosis is:

Accepted Answer

Molluscum contagiosum

Answer

Trichodysplasia spinulosa

Answer

Condyloma acuminata

Answer

Donovanosis

Question 8

A 60-year-old patient presents with unilateral vesicular lesions in a dermatomal distribution on the torso. The lesions are painful and appeared over the past 2-3 days, progressing from erythematous patches to fluid-filled vesicles. The patient reports prodromal burning and tingling sensation in the affected area. Which of the following is the most likely diagnosis?

Accepted Answer

Herpes zoster infection

Answer

Irritant contact dermatitis

Answer

Allergic contact dermatitis

Answer

Herpes Simplex Infection

Question 9

Slapped cheek appearance is associated with which of the following?

Accepted Answer

Parvovirus B19 infection

Answer

Herpes zoster

Answer

Molluscum contagiosum

Answer

Kaposi sarcoma

Question 10

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

Accepted Answer

Herpes Zoster

Answer

Lymphangioma circumscriptum

Answer

Molluscum contagiosum

Answer

Herpes simplex

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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