Viral Skin Infections Practice Questions

Q: A 45-year-old male has multiple grouped vesicular lesions present on the T10 dermatome associated with pain. What is the most likely diagnosis?

Herpes zoster. ### **Explanation** **1. Why Herpes Zoster is Correct:** The clinical presentation of **grouped vesicular lesions** distributed along a **single dermatome** (T10) associated with **pain** (neuralgia) is the classic hallmark of **Herpes Zoster** (Shingles). This condition results from the reactivation of the latent Varicella-Zoster Virus (VZV) in the dorsal root ganglia. The T10 dermatome (level of the umbilicus) is a common site. The unilateral, dermatomal distribution is the most significant diagnostic clue. **2. Why Other Options are Incorrect:** * **Dermatitis Herpetiformis:** While it presents with vesicles, they are typically **symmetrically distributed** on extensor surfaces (elbows, knees) and are associated with intense pruritus and Celiac disease, not dermatomal pain. * **Herpes Simplex:** HSV usually presents as grouped vesicles on a red base, but it is typically localized to the **mucocutaneous junctions** (lips or genitals) and does not follow a specific dermatomal pattern. * **Scabies:** This is a parasitic infestation characterized by **nocturnal itching** and burrows in web spaces. It does not present with grouped vesicles in a dermatomal distribution. **3. High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** Shows **Multinucleated Giant Cells** (common to both HSV and VZV). * **Hutchinson’s Sign:** Vesicles on the tip of the nose indicating involvement of the ophthalmic nerve (Nasociliary branch), risking ocular complications. * **Ramsay Hunt Syndrome:** Involvement of the geniculate ganglion leading to facial palsy and vesicles in the external auditory canal. * **Post-Herpetic Neuralgia (PHN):** The most common complication, defined as pain persisting >3 months after the rash heals. * **Treatment:** Oral Acyclovir (800 mg 5 times/day for 7 days), Valacyclovir, or Famciclovir.

Q: In Tzanck smear, multinucleated cells are seen in which of the following conditions?

Chickenpox. **Explanation:** The **Tzanck smear** is a rapid bedside diagnostic test used primarily to identify acantholytic cells or viral cytopathic effects. In the context of viral infections, the presence of **multinucleated giant cells** (formed by the fusion of infected keratinocytes) is a hallmark finding. * **Why Chickenpox is correct:** Chickenpox (Varicella-Zoster Virus) belongs to the Herpesviridae family. Like Herpes Simplex (HSV), it causes characteristic cytopathic changes including **multinucleation**, nuclear molding, and chromatin margination. These are easily visualized on a Tzanck smear stained with Giemsa or Wright stain. **Analysis of Incorrect Options:** * **Psoriasis:** A chronic inflammatory condition characterized by epidermal hyperplasia (acanthosis) and Munro’s microabscesses (neutrophils in the stratum corneum), not multinucleated cells. * **Molluscum contagiosum:** Caused by a Poxvirus. A Tzanck smear would show **Henderson-Paterson bodies** (large, intracytoplasmic eosinophilic inclusion bodies), not multinucleated cells. * **Pemphigus vulgaris:** While Tzanck smear is used here, it reveals **Acantholytic cells (Tzanck cells)**—which are rounded, detached keratinocytes with hyperchromatic nuclei—but these are typically **mononucleated**, not multinucleated. **High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear Mnemonic:** It is positive in **"CHAMP"**: **C**hickenpox, **H**erpes simplex/Zoster, **A**cantholytic disorders (Pemphigus), **M**olluscum contagiosum (Inclusions), and **P**ustular psoriasis (Neutrophils). * **Key Distinction:** Multinucleated giant cells help differentiate Herpes group viruses from other vesicular eruptions but *cannot* distinguish between HSV-1, HSV-2, and VZV. * **Stains used:** Giemsa, Wright, or Leishman stain.

Q: Infection by which virus gives rise to the following skin lesions?

Varicella zoster virus. ***Varicella zoster virus*** - Produces the characteristic **polymorphous vesicular rash** described as "**dew drops on rose petals**" - vesicles of different stages on an erythematous base. - The lesions appear in **crops** with vesicles, pustules, and crusts present simultaneously, typically starting on the **trunk** and spreading centripetally. *Herpesvirus* - Causes **grouped vesicles** on an erythematous base, typically clustered in a small area rather than widespread. - Lesions are usually **recurrent** at the same anatomical site and are **monomorphic** (same stage of development). *Measles virus* - Produces a **maculopapular rash** that starts behind the ears and spreads cephalocaudally, not vesicular lesions. - Associated with **Koplik's spots** in the mouth and systemic symptoms like **cough**, **coryza**, and **conjunctivitis**. *Parvovirus* - Causes **erythema infectiosum** with a characteristic "**slapped cheek**" appearance followed by a **lacy reticular rash** on extremities. - The rash is **maculopapular** and **non-vesicular**, completely different from the vesicular pattern described.

Q: What is the treatment of choice for genital warts in pregnancy?

Cryotherapy. **Explanation:** The treatment of choice for genital warts (Condyloma acuminata) in pregnancy is **Cryotherapy** (using liquid nitrogen). During pregnancy, the goal of treatment is to remove symptomatic warts and reduce the viral load before delivery to minimize the risk of juvenile-onset recurrent respiratory papillomatosis (JORRP) in the neonate. Cryotherapy is preferred because it is a **physical modality** that is safe, non-teratogenic, and lacks systemic absorption. **Why the other options are incorrect:** * **Podophyllotoxin (Option C):** This is strictly **contraindicated** in pregnancy due to its potent antimitotic effects, which can lead to systemic toxicity and potential fetal death or congenital anomalies. * **Imiquimod (Option B):** While it is an immune response modifier used for warts in non-pregnant patients, it is generally avoided in pregnancy due to a lack of sufficient safety data (Category C). * **Salicylic acid (Option A):** It is generally avoided for genital mucosal surfaces due to its corrosive nature and potential for systemic absorption (salicylism), especially over large surface areas. **High-Yield Clinical Pearls for NEET-PG:** * **Safe alternatives in pregnancy:** Trichloroacetic acid (TCA) 80-90% and surgical excision/electrocautery are also considered safe. * **Causative agents:** HPV types 6 and 11 (Low risk). * **Delivery Method:** Genital warts are *not* an absolute indication for Cesarean section unless they physically obstruct the birth canal or are likely to cause massive hemorrhage during labor. * **Most common viral STI:** HPV is the most common viral sexually transmitted infection worldwide.

Q: A 23-year-old, sexually active man has been treated for Neisseria gonorrhoeae infection 6 times during the past 5 years. He now comes to the physician because of the increasing number and size of warty lesions slowly enlarging on his external genitalia during the past year. On physical examination, there are multiple 1- to 3-mm sessile, nonulcerated, papillary excrescences over the inner surface of the penile prepuce. These lesions are excised, but 2 years later, similar lesions appear. Which of the following conditions most likely predisposed him to the development of these recurrent lesions?

Human papillomavirus infection. ### Explanation **Correct Answer: C. Human papillomavirus (HPV) infection** The clinical presentation of multiple, sessile, nonulcerated, papillary excrescences on the genitalia is classic for **Condyloma acuminatum** (anogenital warts). These are caused by **Human Papillomavirus (HPV)**, most commonly types **6 and 11**. The patient’s history of recurrent STIs (gonorrhea) indicates high-risk sexual behavior, which is the primary risk factor for acquiring HPV. The recurrence of these lesions after excision is a hallmark of HPV, as the virus often remains latent in the basal layer of the surrounding skin or mucosa, leading to new lesions even after the physical removal of visible warts. **Analysis of Incorrect Options:** * **A. Candida albicans:** Typically presents as balanitis (inflammation of the glans) with erythema, itching, and a "cheesy" white discharge, not as organized papillary growths. * **B. Circumcision:** This is actually a **protective factor**. Circumcision reduces the risk of acquiring HPV and other STIs because the removal of the prepuce eliminates a warm, moist environment conducive to viral persistence. * **D. Neisseria gonorrhoeae:** While the patient has a history of gonorrhea, this bacterium causes urethritis (purulent discharge and dysuria), not verrucous skin lesions. It does not predispose to warts, though its presence indicates a high risk for co-infection with HPV. **NEET-PG High-Yield Pearls:** * **Etiology:** HPV 6 and 11 (Low risk - warts); HPV 16 and 18 (High risk - associated with squamous cell carcinoma of the cervix, anus, and penis). * **Histopathology:** Look for **Koilocytes** (squamous epithelial cells with perinuclear halos and wrinkled "raisinoid" nuclei). * **Treatment:** Podophyllin, Imiquimod (immunomodulator), cryotherapy, or surgical excision. * **Prevention:** The quadrivalent and nonavalent HPV vaccines are effective against types 6 and 11.

Q: Which of the following is NOT true about Molluscum contagiosum?

It is treated with metronidazole and doxycycline.. **Explanation:** **Molluscum Contagiosum** is a common viral skin infection caused by a **Poxvirus** (specifically a double-stranded DNA virus). In adults, it is often transmitted sexually and presents as small, firm, pearly, umbilicated papules on the lower abdomen, thighs, or genitalia. **Why Option D is the correct answer (False statement):** Molluscum contagiosum is a **viral infection**, not a bacterial or protozoal one. **Metronidazole** is used for anaerobic bacteria and protozoa (like *Trichomonas vaginalis*), while **Doxycycline** is used for Chlamydia, Syphilis, or PID. These antibiotics have no efficacy against the poxvirus. Treatment for Molluscum is typically destructive (cryotherapy, curettage) or expectant, as it is often self-limiting. **Analysis of other options:** * **Option A:** Correct. It is caused by the *Molluscipoxvirus*, a member of the Poxviridae family. * **Option B:** Correct. While common in children, extensive or giant lesions in adults are a hallmark of **immunocompromised states**, particularly **HIV/AIDS**. * **Option C:** Correct. Management includes physical destruction of the lesions via **cryotherapy** (liquid nitrogen), curettage, or topical agents like podophyllotoxin or potassium hydroxide. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Feature:** Central umbilication (dimple) on a pearly papule. * **Histopathology:** Presence of **Henderson-Paterson bodies** (large, intracytoplasmic eosinophilic inclusion bodies) is a classic exam finding. * **Transmission:** Skin-to-skin contact or fomites. In children, it is non-sexual; in adults, it is considered an STI. * **HIV Correlation:** If a patient presents with extensive facial molluscum, always screen for HIV.

Q: Which of the following occupations is a risk factor for the presenting illness?

A lifeguard in a swimming pool. ***A lifeguard in a swimming pool*** - **Molluscum contagiosum** spreads through direct contact with infected individuals and contaminated surfaces like **pool decks, diving boards**, and shared equipment. - Swimming pool environments facilitate **fomite transmission** as the virus can survive on wet surfaces and be transmitted through shared towels and pool equipment. *A poultry worker* - Poultry workers are at risk for **avian influenza**, **Salmonella**, and **Campylobacter** infections, not **molluscum contagiosum**. - **Molluscum contagiosum** is a **human-specific poxvirus** that does not affect or transmit through poultry. *Farmer* - Farmers are typically exposed to **zoonotic infections** like **anthrax**, **brucellosis**, and **Q fever** from livestock contact. - **Molluscum contagiosum** transmission occurs through **human-to-human contact** and contaminated surfaces, not agricultural exposure. *A kennel worker* - Kennel workers face risks of **dog bites**, **cat scratch disease**, **ringworm**, and **toxoplasmosis** from animal contact. - **Molluscum contagiosum** does not transmit from animals to humans as it is a **human-specific viral infection**.

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

Molluscum contagiosum. ***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 1

A 45-year-old male has multiple grouped vesicular lesions present on the T10 dermatome associated with pain. What is the most likely diagnosis?

Accepted Answer

Herpes zoster

Answer

Dermatitis herpetiformis

Answer

Herpes simplex

Answer

Scabies

Question 2

In Tzanck smear, multinucleated cells are seen in which of the following conditions?

Accepted Answer

Chickenpox

Answer

Psoriasis

Answer

Molluscum contagiosum

Answer

Pemphigus vulgaris

Question 3

A 69-year-old man presents with a gradual onset of pain, tingling, and hyperesthesia in the medial aspect of his right arm. Subsequently, he develops erythema and an outbreak of vesicles on the medial aspect of his right arm, extending from his medial epicondyle to the wrist. After several days, the lesions crust over and resolve, but he is left with a residual "burning" pain in the same distribution as the lesions, with occasional sharp pain provoked by touch. The infectious agent responsible for this condition resides in which part of the neuraxis?

Accepted Answer

Dorsal root ganglion

Answer

Brainstem

Answer

Sensory nerve axon

Answer

Sensory nerve root

Question 4

Infection by which virus gives rise to the following skin lesions?

Accepted Answer

Varicella zoster virus

Answer

Herpesvirus

Answer

Measles virus

Answer

Parvovirus

Question 5

What is the treatment of choice for genital warts in pregnancy?

Accepted Answer

Cryotherapy

Answer

Salicylic acid with lactic acid solution

Answer

Imiquimod

Answer

Podophyllotoxin

Question 6

A 23-year-old, sexually active man has been treated for Neisseria gonorrhoeae infection 6 times during the past 5 years. He now comes to the physician because of the increasing number and size of warty lesions slowly enlarging on his external genitalia during the past year. On physical examination, there are multiple 1- to 3-mm sessile, nonulcerated, papillary excrescences over the inner surface of the penile prepuce. These lesions are excised, but 2 years later, similar lesions appear. Which of the following conditions most likely predisposed him to the development of these recurrent lesions?

Accepted Answer

Human papillomavirus infection

Answer

Candida albicans infection

Answer

Circumcision

Answer

Neisseria gonorrhoeae infection

Question 7

Which of the following is NOT true about Molluscum contagiosum?

Accepted Answer

It is treated with metronidazole and doxycycline.

Answer

It is caused by a poxvirus.

Answer

It is commonly seen in HIV-infected and immunocompromised individuals.

Answer

Treatment can include cryotherapy.

Question 8

Which of the following occupations is a risk factor for the presenting illness?

Accepted Answer

A lifeguard in a swimming pool

Answer

A poultry worker

Answer

Farmer

Answer

A kennel worker

Question 9

A 25-year-old presents with painful vesicular lesions on the lips. A Tzanck smear from the lesion base shows multinucleated giant cells. What is the most likely causative agent?

Accepted Answer

Herpes simplex virus

Answer

Coxsackievirus A16

Answer

Human papillomavirus

Answer

Varicella-zoster virus

Question 10

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

Accepted Answer

Molluscum contagiosum

Answer

Acne vulgaris

Answer

HPV

Answer

Herpes simplex

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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