Viral Skin Infections Practice Questions

Q: Microscopy of a Tzank smear from a patient presenting with a shin vesicle showed giant cells. What is the causative agent?

Varicella zoster. **Explanation:** The presence of **multinucleated giant cells** on a Tzanck smear is a hallmark diagnostic finding for infections caused by the **Herpesviridae** family, specifically Herpes Simplex Virus (HSV-1, HSV-2) and **Varicella-Zoster Virus (VZV)**. The Tzanck smear is performed by scraping the base of a freshly opened vesicle. Under the microscope (stained with Giemsa or Wright stain), one observes "Tzanck cells," which are large, multinucleated keratinocytes formed by the fusion of infected cells (syncytia) and characteristic "ground-glass" nuclei with peripheral chromatin condensation. **Analysis of Options:** * **Varicella Zoster (Correct):** As a member of the Alpha-herpesvirinae subfamily, it typically presents with vesicular eruptions (Chickenpox or Shingles) and shows positive Tzanck smear findings. * **Vaccinia Virus:** A Poxvirus used in smallpox vaccines. It produces **Guarnieri bodies** (intracytoplasmic eosinophilic inclusions), not multinucleated giant cells. * **Tuberculosis:** Cutaneous TB (like Lupus Vulgaris) shows granulomatous inflammation with Langhans giant cells on histopathology, but it does not present with acute vesicles or a positive Tzanck smear. * **Molluscum Contagiosum:** Caused by a Poxvirus, it presents with umbilicated papules. Microscopy reveals **Henderson-Paterson bodies** (large, intracytoplasmic viral inclusion bodies). **NEET-PG High-Yield Pearls:** 1. **Tzanck Smear Mnemonic:** Remember **"3H"** – **H**SV, **H**ZV, and **H**ailey-Hailey disease/Pemphigus (acantholytic cells). 2. **Inclusion Bodies:** HSV/VZV show **Cowdry Type A** intranuclear inclusions. 3. **Limitation:** A Tzanck smear can identify a Herpes group infection but **cannot differentiate** between HSV-1, HSV-2, and VZV. Viral culture or PCR is required for specific typing.

Q: A patient presents with painful blisters along the chest wall. All of the following tests are useful for diagnosis except?

LDH levels. **Explanation:** The clinical presentation of painful blisters along a dermatome (chest wall) is characteristic of **Herpes Zoster (Shingles)**, caused by the reactivation of the Varicella-Zoster Virus (VZV). **Why LDH levels is the correct answer:** Lactate Dehydrogenase (LDH) is a non-specific marker of tissue damage or hemolysis. While it may be elevated in certain malignancies or severe systemic infections, it has **no diagnostic utility** in identifying viral skin infections like Herpes Zoster. Diagnosis of VZV is primarily clinical or confirmed through virus-specific laboratory methods. **Analysis of other options:** * **Tzanck Smear:** A rapid, bedside test where a scraping from the base of the vesicle is stained (e.g., Giemsa). It reveals **multinucleated giant cells** and Cowdry Type A inclusion bodies, characteristic of the Herpesviridae family. * **Direct Fluorescent Antibody (DFA):** This involves using fluorescein-labeled antibodies to detect specific viral antigens in skin scrapings. It is more sensitive and specific than the Tzanck smear. * **Polymerase Chain Reaction (PCR):** This is the **gold standard** and the most sensitive method for detecting VZV DNA from vesicle fluid or crusts. **NEET-PG High-Yield Pearls:** * **Cowdry Type A bodies:** Intranuclear eosinophilic inclusion bodies seen in HSV and VZV. * **Tzanck Smear limitation:** It can identify the Herpes family but **cannot differentiate** between HSV-1, HSV-2, and VZV. * **Dermatomal distribution:** VZV stays latent in the **dorsal root ganglia**; its reactivation follows a specific nerve distribution (unilateral). * **Post-herpetic neuralgia:** The most common complication of Shingles, especially in the elderly.

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.

Question 1

Microscopy of a Tzank smear from a patient presenting with a shin vesicle showed giant cells. What is the causative agent?

Accepted Answer

Varicella zoster

Answer

Vaccinia virus

Answer

Tuberculous

Answer

Molluscum contagiosum

Question 2

A patient presents with painful blisters along the chest wall. All of the following tests are useful for diagnosis except?

Accepted Answer

LDH levels

Answer

Direct Fluorescent antibody

Answer

Polymerase chain reaction

Answer

Tzank smear

Question 3

A young patient complains of shooting pain, paresthesia, and tenderness on one side of the palate. Unilateral vesicles appear in clusters. The patient gives a previous history of chickenpox. What is the most likely diagnosis?

Accepted Answer

Herpes zoster

Answer

Herpes simplex

Answer

Herpangina

Answer

Behçet's syndrome

Question 4

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 5

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 6

What is the primary treatment for Herpes zoster?

Accepted Answer

Valacyclovir

Answer

Zidovudine

Answer

Ribavirin

Answer

Nevirapine

Question 7

What is the commonest site of involvement in herpes zoster?

Accepted Answer

Thoracic region

Answer

Cranial nerve

Answer

Face

Answer

Lumbar region

Question 8

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 9

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 10

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

Viral Skin Infections — MCQs

Viral Skin Infections — MCQs

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