Viral Skin Infections Practice Questions

Q: Inflammation of the dorsal root ganglion and vesicular eruption of the skin and mucous membrane in the area supplied by an affected sensory nerve is characteristic of what condition?

Herpes zoster. ### Explanation **Correct Option: A. Herpes zoster** Herpes zoster (Shingles) is caused by the reactivation of the **Varicella-Zoster Virus (VZV)**, which remains latent in the **dorsal root ganglia** or cranial nerve ganglia after a primary chickenpox infection. When the virus reactivates, it travels down the sensory nerve, causing intense inflammation of the ganglion and a characteristic **vesicular eruption** strictly following the **dermatomal distribution** of that nerve. In the head and neck, the trigeminal nerve (especially the ophthalmic division) is frequently involved. **Why other options are incorrect:** * **B. Herpes simplex:** While it causes vesicular eruptions, it typically presents as recurrent localized lesions (like cold sores) and does not typically involve the widespread inflammation of the dorsal root ganglion or a strict dermatomal pattern characteristic of Zoster. * **C. Uveoparotid fever (Heerfordt's syndrome):** This is a manifestation of **Sarcoidosis** characterized by the triad of parotid enlargement, uveitis, and facial nerve palsy. It is a granulomatous disease, not a viral vesicular eruption. * **D. Aphthous stomatitis:** These are common, painful, non-infectious **ulcers** (not vesicles) found on non-keratinized oral mucosa. They do not involve sensory ganglia or skin eruptions. **NEET-PG Clinical Pearls:** * **Ramsay Hunt Syndrome (Herpes Zoster Oticus):** Reactivation involving the **geniculate ganglion** of the Facial Nerve (CN VII). Clinical triad: Facial palsy, vesicles in the external auditory canal/auricle, and vestibulocochlear symptoms (tinnitus/vertigo). * **Tzanck Smear:** Used for diagnosis; shows **multinucleated giant cells** and Cowdry Type A inclusion bodies. * **Hutchinson’s Sign:** Vesicles on the tip of the nose indicating involvement of the nasociliary nerve, predicting a high risk of ocular complications.

Q: Which of the following is most commonly associated with erythema multiforme?

Herpes Simplex Virus (HSV). **Explanation:** **Erythema Multiforme (EM)** is a Type IV hypersensitivity reaction characterized by the sudden onset of symmetric, "targetoid" (iris) lesions. **Why Herpes Simplex Virus (HSV) is correct:** HSV is the **most common trigger** for Erythema Multiforme, accounting for up to 90% of cases (specifically EM Minor). The pathogenesis involves the transport of HSV DNA fragments by macrophages to keratinocytes, which triggers a T-cell mediated immune response. Both HSV-1 (oral) and HSV-2 (genital) can precede the eruption by 1–2 weeks. **Why other options are incorrect:** * **Staphylococcus:** While *Staphylococcal Scalded Skin Syndrome (SSSS)* and *Toxic Shock Syndrome* are dermatological emergencies, Staph is not a primary trigger for EM. * **Tuberculosis:** Though TB can cause various skin manifestations (like Lupus Vulgaris or Erythema Nodosum), it is a very rare cause of EM. * **Epstein-Barr Virus (EBV):** EBV can cause EM, but it is significantly less common than HSV. EBV is more typically associated with infectious mononucleosis and oral hairy leukoplakia. **High-Yield Clinical Pearls for NEET-PG:** * **Target Lesion:** Consists of three zones—a central dusky/blistered area, a pale edematous ring, and an outer erythematous halo. * **EM Minor vs. Major:** EM Minor has minimal mucosal involvement; **EM Major** involves at least two mucosal surfaces (oral, ocular, or genital). * **Drug Triggers:** While viruses (HSV) are the most common cause of EM, drugs (Sulfonamides, NSAIDs, Anticonvulsants) are the most common cause of Stevens-Johnson Syndrome (SJS). * **Recurrence:** Recurrent EM is almost always associated with subclinical or overt HSV reactivation.

Q: What is the primary treatment for Herpes zoster?

Valacyclovir. **Explanation:** **Herpes zoster (Shingles)** is caused by the reactivation of the **Varicella-Zoster Virus (VZV)** latent in the sensory ganglia. The primary goal of treatment is to limit viral replication, accelerate healing, and reduce the risk of post-herpetic neuralgia (PHN). **Why Valacyclovir is correct:** Valacyclovir is a prodrug of Acyclovir with significantly higher oral bioavailability. It inhibits viral DNA polymerase, leading to chain termination. It is preferred over Acyclovir in clinical practice due to its **superior pharmacokinetic profile** and less frequent dosing (TID vs. 5 times/day for Acyclovir), which improves patient compliance. Famciclovir is another equivalent option. **Why the other options are incorrect:** * **A. Zidovudine (AZT):** A Nucleoside Reverse Transcriptase Inhibitor (NRTI) used exclusively in the treatment of **HIV/AIDS**. * **C. Ribavirin:** A broad-spectrum antiviral used primarily for **Hepatitis C** (in combination) and **RSV** (Respiratory Syncytial Virus) infections. * **D. Nevirapine:** A Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) used in **HIV** management and for preventing mother-to-child transmission. **High-Yield Clinical Pearls for NEET-PG:** * **The "72-hour Rule":** Antiviral therapy is most effective when initiated within 72 hours of rash onset. * **Tzanck Smear:** Shows **Multinucleated Giant Cells** with Cowdry Type A intranuclear inclusions (common to HSV and VZV). * **Complication:** Post-herpetic neuralgia is the most common complication; Ramsay Hunt Syndrome occurs when the Geniculate ganglion is involved. * **Vaccination:** The Recombinant Zoster Vaccine (Shingrix) is recommended for adults >50 years to prevent reactivation.

Q: What is the commonest site of involvement in herpes zoster?

Thoracic region. **Explanation:** **Herpes Zoster (Shingles)** is caused by the reactivation of the latent Varicella-Zoster Virus (VZV) within the sensory ganglia. The virus remains dormant in the dorsal root ganglia after a primary chickenpox infection and reactivates when cell-mediated immunity declines. **Why Thoracic region is correct:** The distribution of the rash follows specific dermatomes. The **thoracic dermatomes (T3 to L2)** are the most frequently involved sites, accounting for over **50-60% of all cases** [1]. This is because the primary infection (chickenpox) often features a high density of lesions on the trunk, leading to a higher viral load seeding the corresponding thoracic sensory ganglia. **Analysis of Incorrect Options:** * **Cranial nerve & Face:** While the Trigeminal nerve (especially the ophthalmic division, leading to *Herpes Zoster Ophthalmicus*) is the most common cranial nerve involved, it occurs less frequently than thoracic involvement (approx. 10-20% of cases). * **Lumbar region:** Though common, lumbar involvement occurs less frequently than thoracic involvement. The frequency of reactivation generally correlates with the density of the original varicella rash in that area. **High-Yield Clinical Pearls for NEET-PG:** * **Hutchinson’s Sign:** Vesicles on the tip or side of the nose indicate involvement of the nasociliary branch of the trigeminal nerve and predict a high risk of ocular complications. * **Ramsay Hunt Syndrome:** Reactivation in the geniculate ganglion involving CN VII and VIII, presenting with facial palsy and vesicles in the external auditory canal. * **Post-Herpetic Neuralgia (PHN):** The most common complication, defined as pain persisting >90 days after the rash onset [1]. * **Treatment:** Oral Acyclovir, Valacyclovir, or Famciclovir is most effective when started within **72 hours** of rash onset [1].

Q: A 40-year-old patient presents with tumor-like lesions on the arms, legs, and buttocks. Histology showed hyaline acidophilic inclusion bodies. What is the diagnosis?

Molluscum contagiosum. ### Explanation **Correct Answer: D. Molluscum contagiosum** The clinical presentation of tumor-like skin lesions combined with the specific histological finding of **hyaline acidophilic inclusion bodies** is pathognomonic for **Molluscum contagiosum**. These inclusions, known as **Henderson-Patterson bodies**, are large, eosinophilic, intracytoplasmic structures found in the stratum spinosum and stratum corneum. They represent the site of viral replication (Poxvirus) and displace the host cell nucleus to the periphery. Clinically, these lesions appear as pearly, umbilicated papules. **Why other options are incorrect:** * **Cowpox (A):** While it is a Poxvirus, it typically presents as a single painful, inflamed pustule or ulcer (usually on the hands) acquired from infected animals. It shows **Guarnieri bodies** (intracytoplasmic inclusions), but not the classic Henderson-Patterson bodies. * **Milker's nodule (B):** Caused by the Parapoxvirus, it presents as small, red-to-purple nodules on the fingers of those handling infected cattle. Histology shows vacuolization of the epidermis but lacks the large hyaline inclusions of Molluscum. * **Orf (C):** Also a Parapoxvirus (from sheep/goats), it presents as a solitary "targetoid" nodule that progresses through stages (maculopapular to necrotic). It does not produce the characteristic hyaline bodies seen in this case. **High-Yield Clinical Pearls for NEET-PG:** * **Henderson-Patterson bodies:** Large, eosinophilic, intracytoplasmic inclusions (Molluscum). * **Guarnieri bodies:** Intracytoplasmic inclusions seen in Smallpox and Vaccinia. * **Paschen bodies:** Smallest infectious particles of Variola virus. * **Clinical sign:** Look for "umbilicated papules" in the history. In adults, if lesions are extensive or involve the face, consider **HIV/Immunosuppression**.

Q: A 13-year-old girl presents with two non-tender lesions on her fingers that appeared over 5 months. Examination reveals 0.5-cm slightly raised, pebbly-surfaced, gray-white papules, one on the dorsum of her distal right index finger, and another periungual to her little finger. The lesions gradually disappear over the next 18 months. Which of the following is the most likely factor in the pathogenesis of her lesions?

Human papillomavirus infection. **Explanation:** The clinical presentation of slightly raised, pebbly-surfaced, gray-white papules in a pediatric patient is classic for **Verruca Vulgaris (Common Warts)**. **1. Why the Correct Answer is Right:** Verruca vulgaris is caused by **Human Papillomavirus (HPV)**, most commonly types **1, 2, 4, and 7**. These viruses infect the basal layer of the epithelium, leading to epidermal hyperplasia (acanthosis) and hyperkeratosis. The "pebbly" or "verrucous" surface is a hallmark of HPV-induced skin changes. A key feature of viral warts, especially in children, is their tendency for **spontaneous regression** (as seen in this patient over 18 months) due to the development of a cell-mediated immune response. **2. Why Incorrect Options are Wrong:** * **A. BRAF gene mutation:** This is associated with melanocytic neoplasms, most notably **Malignant Melanoma** and Seborrheic Keratosis. It does not cause infectious verrucous papules. * **C. IgA antibody deposition:** This is the hallmark of **Dermatitis Herpetiformis** (associated with Celiac disease) or IgA Vasculitis (HSP). It presents as pruritic vesicles or purpura, not painless pebbly papules. * **D. Type IV hypersensitivity reaction:** This is the mechanism behind **Allergic Contact Dermatitis**. While it involves T-cells, it typically presents with acute erythema, scaling, and intense itching rather than stable, discrete viral papules. **3. NEET-PG High-Yield Pearls:** * **Histopathology:** Look for **Koilocytes** (cells with perinuclear halos and wrinkled nuclei) in the upper epidermis. * **Clinical Sign:** **Auspitz-like bleeding** (pinpoint bleeding) occurs when the surface is pared down due to the presence of elongated dermal papillae with prominent capillaries. * **Koebner Phenomenon:** Warts can spread linearly along lines of trauma (Pseudo-Koebner). * **Treatment:** Salicylic acid (keratolytic), cryotherapy (liquid nitrogen), or imiquimod.

Q: Multinucleate giant cells are seen in Tzanck smear in which of the following conditions?

Herpes genitalis. **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 **multinucleate giant cells** (formed by the fusion of infected keratinocytes) is a hallmark of the **Herpesviridae** family. **1. Why Herpes Genitalis is Correct:** Herpes genitalis is caused by Herpes Simplex Virus (HSV-2 or HSV-1). The virus induces characteristic changes in epithelial cells, including ballooning degeneration and the formation of multinucleated giant cells with "molding" of nuclei. These are easily visualized on a Tzanck smear stained with Giemsa or Wright stain. **2. Analysis of Incorrect Options:** * **Pemphigus (Option D):** While Tzanck smear is used here, it shows **Acantholytic cells (Tzanck cells)**—rounded, detached keratinocytes with hyperchromatic nuclei—rather than multinucleate giant cells. * **Bullous Pemphigoid (Option B):** This is a subepidermal blistering disease. A Tzanck smear typically shows an inflammatory infiltrate (predominantly **eosinophils**) but lacks acantholytic or multinucleate cells. * **Toxic Epidermal Necrolysis (Option C):** Tzanck smear reveals **necrotic keratinocytes** and inflammatory cells, reflecting the full-thickness epidermal death characteristic of the condition. **NEET-PG High-Yield Pearls:** * **Tzanck Smear Positivity:** Positive in HSV, VZV (Chickenpox/Shingles), and Pemphigus vulgaris. * **Viral Cytopathic Effect:** Look for the "3 Ms": **M**ultinucleation, Nuclear **M**argination of chromatin, and Nuclear **M**olding. * **Limitation:** Tzanck smear **cannot** differentiate between HSV-1, HSV-2, and VZV; for specific typing, PCR or viral culture is required.

Q: Multiple nodular lesions occurring most commonly on the lower lip, resembling oral papillomas and microscopically containing virus-like particles are most likely to be what condition?

Heck disease. ### Explanation **Heck Disease (Focal Epithelial Hyperplasia)** Heck disease is a rare, benign condition caused by **Human Papillomavirus (HPV) types 13 and 32**. It typically presents as multiple, soft, smooth, flattened or rounded papules/nodules on the oral mucosa, most frequently involving the **lower lip**, buccal mucosa, and tongue. * **Pathogenesis:** It is characterized by acanthosis and thickening of the epithelium. Microscopically, it shows "mitosoid cells" (cells with degenerating nuclei resembling mitotic figures) and virus-like particles under electron microscopy. * **Clinical Context:** It is most common in children and young adults, often showing a familial clustering or association with low socioeconomic status. **Analysis of Incorrect Options:** * **Fordyce Spots:** These are ectopic sebaceous glands. They appear as small (1-2 mm), yellowish-white granules on the vermilion border of the lips or buccal mucosa. They are not viral and do not form large nodular lesions. * **Lingual Varices:** These are dilated, tortuous veins (varicosities) typically found on the ventral surface of the tongue in elderly patients. They appear bluish-purple and are vascular, not epithelial/viral. * **Linea Alba:** This is a common white, horizontal line on the buccal mucosa at the level of the occlusal plane, caused by friction or pressure from teeth (hyperkeratosis). It is not nodular or viral. **High-Yield Pearls for NEET-PG:** * **Causative Agents:** HPV 13 and 32 (High-yield association). * **Mitosoid Cells:** The pathognomonic histological feature of Heck disease. * **Management:** Usually self-limiting; treatment (cryotherapy or CO2 laser) is only for cosmetic or functional concerns. * **Differential Diagnosis:** Must be distinguished from Condyloma acuminatum (HPV 6, 11), which usually has a more "cauliflower" appearance and a different transmission pattern.

Q: A 26-year-old male kidney transplant recipient presents with multiple brown keratotic papules on the forehead and scalp. What is the common cause of these lesions?

HPV subtype 3, 10. ### Explanation The clinical presentation describes **Verruca Plana (Flat Warts)**. These are characterized by small (1–5 mm), flat-topped, smooth or slightly keratotic, flesh-colored to brown papules. They commonly occur on the face, forehead, and dorsum of hands. In immunocompromised individuals, such as kidney transplant recipients, these lesions can be more numerous and persistent due to impaired cell-mediated immunity. **Why Option C is correct:** * **HPV subtypes 3 and 10** are the specific genotypes responsible for Verruca Plana. The description of "brown keratotic papules" on the forehead is the classic clinical vignette for this condition. **Why other options are incorrect:** * **Option A (HPV 6, 11):** These cause **Condyloma Acuminata** (Anogenital warts) and Laryngeal Papillomatosis. They are low-risk mucosal types. * **Option B (HPV 2, 4):** These are the most common causes of **Verruca Vulgaris** (Common warts), which are typically rough, exophytic, "cauliflower-like" lesions found on fingers and periungual areas. * **Option D (HPV 16, 18):** These are high-risk oncogenic types associated with **Bowenoid papulosis**, cervical cancer, and squamous cell carcinoma. **High-Yield Clinical Pearls for NEET-PG:** * **Koebner Phenomenon:** Flat warts often show linear distribution due to autoinoculation (e.g., from shaving or scratching). * **Butcher’s Warts:** Caused by HPV-7. * **Deep Palmoplantar Warts (Myrmecia):** Caused by HPV-1. * **Epidermodysplasia Verruciformis (EV):** A rare genetic condition associated with HPV-5 and HPV-8, which carries a high risk of progression to Squamous Cell Carcinoma (SCC). * **Treatment:** First-line includes topical salicylic acid, cryotherapy, or topical retinoids (especially for flat warts).

Q: Podophyllin is used to treat which type of wart?

Genital wart. **Explanation:** **Podophyllin** (Podophyllum resin) is a potent cytotoxic agent derived from the Mayapple plant. It works by binding to tubulin, inhibiting mitotic spindle formation, which leads to cell cycle arrest and necrosis of the treated tissue. **Why Genital Warts (Condyloma Acuminata) is correct:** Podophyllin is specifically indicated for the treatment of **anogenital warts** caused by Human Papillomavirus (HPV) types 6 and 11. Because it is highly caustic and can be systemically absorbed, it is primarily used on mucosal or thin-skinned areas where penetration is effective. It must be applied by a healthcare professional and washed off after 4–6 hours to prevent severe local irritation or systemic toxicity. **Why other options are incorrect:** * **Plantar Warts (Verruca Plantaris):** These occur on the thick, keratinized skin of the soles. Podophyllin lacks the penetrative power to bypass this thick stratum corneum. Salicylic acid or cryotherapy are preferred. * **Verruca Plana (Flat Warts):** These are usually multiple and located on the face or dorsum of hands. Podophyllin is too corrosive for facial use and carries a high risk of scarring and post-inflammatory hyperpigmentation. **Clinical Pearls for NEET-PG:** * **Contraindication:** Podophyllin is strictly **contraindicated in pregnancy** due to its teratogenic potential and risk of fetal death. * **Podophyllotoxin:** This is the active purified fraction of podophyllin. Unlike the resin, it is stable and can be self-applied by the patient. * **Systemic Toxicity:** Over-application or failure to wash it off can lead to "Podophyllin Toxicity," characterized by bone marrow suppression, neurotoxicity (coma/seizures), and multi-organ failure.

Question 1

Inflammation of the dorsal root ganglion and vesicular eruption of the skin and mucous membrane in the area supplied by an affected sensory nerve is characteristic of what condition?

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Uveoparotid fever

Answer

Aphthous stomatitis

Question 2

Which of the following is most commonly associated with erythema multiforme?

Accepted Answer

Herpes Simplex Virus (HSV)

Answer

Staphylococcus

Answer

Tuberculosis

Answer

Epstein-Barr Virus (EBV)

Question 3

What is the primary treatment for Herpes zoster?

Accepted Answer

Valacyclovir

Answer

Zidovudine

Answer

Ribavirin

Answer

Nevirapine

Question 4

What is the commonest site of involvement in herpes zoster?

Accepted Answer

Thoracic region

Answer

Cranial nerve

Answer

Face

Answer

Lumbar region

Question 5

A 40-year-old patient presents with tumor-like lesions on the arms, legs, and buttocks. Histology showed hyaline acidophilic inclusion bodies. What is the diagnosis?

Accepted Answer

Molluscum contagiosum

Answer

Cowpox

Answer

Milker's nodule

Answer

Orf

Question 6

A 13-year-old girl presents with two non-tender lesions on her fingers that appeared over 5 months. Examination reveals 0.5-cm slightly raised, pebbly-surfaced, gray-white papules, one on the dorsum of her distal right index finger, and another periungual to her little finger. The lesions gradually disappear over the next 18 months. Which of the following is the most likely factor in the pathogenesis of her lesions?

Accepted Answer

Human papillomavirus infection

Answer

BRAF gene mutation

Answer

IgA antibody deposition

Answer

Type IV hypersensitivity reaction

Question 7

Multinucleate giant cells are seen in Tzanck smear in which of the following conditions?

Accepted Answer

Herpes genitalis

Answer

Bullous pemphigoid

Answer

Toxic epidermal necrolysis

Answer

Pemphigus

Question 8

Multiple nodular lesions occurring most commonly on the lower lip, resembling oral papillomas and microscopically containing virus-like particles are most likely to be what condition?

Accepted Answer

Heck disease

Answer

Fordyce spots

Answer

Lingual varices

Answer

Linea alba

Question 9

A 26-year-old male kidney transplant recipient presents with multiple brown keratotic papules on the forehead and scalp. What is the common cause of these lesions?

Accepted Answer

HPV subtype 3, 10

Answer

HPV subtype 6, 11

Answer

HPV subtype 2, 4

Answer

HPV subtype 16, 18

Question 10

Podophyllin is used to treat which type of wart?

Accepted Answer

Genital wart

Answer

Plantar wart

Answer

Verruca plana

Answer

All of the above

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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