Viral Skin Infections — MCQs

Q: In a primary lesion of herpes, what is typically seen?

vesicle. ***Vesicle*** - A primary herpes lesion typically begins as a **macule**, progresses to a **papule**, and then forms a classic **vesicle** (small, fluid-filled blister) on an erythematous base. - These vesicles often cluster together (**herpetiform**) and are characteristic of both HSV-1 (oral herpes) and HSV-2 (genital herpes) infections. *Ulcer* - An **ulcer** forms when the vesicles rupture and erode, which is a secondary stage of the lesion, not the primary eruption. - While ulcers are common in herpes infections, they represent a progression from the initial vesicular stage. *Papule* - A **papule** is a solid, raised lesion less than 1 cm in diameter, which is an early stage of herpes before fluid accumulation. - While present early, the defining primary lesion with fluid content is the vesicle, distinguishing it from other papular rashes. *Bullae* - **Bullae** are large blisters, greater than 1 cm in diameter, which are generally not typical for uncomplicated herpes simplex infections. - While extensive or severe infections might present with larger blisters, the classic primary lesion is a smaller vesicle.

Q: In a Tzanck smear, which condition is characterized by the presence of multinucleated giant cells?

Varicella (Chickenpox). ***Varicella (Chickenpox)*** * A **Tzanck smear** showing **multinucleated giant cells** and **acantholytic cells** is highly characteristic of herpesvirus infections, including varicella-zoster virus (VZV) causing chickenpox. * These giant cells are formed by the fusion of infected cells, and their presence helps confirm a diagnosis of either **herpes simplex** or **varicella-zoster** infection. *Psoriasis vulgaris* * A Tzanck smear in psoriasis typically shows **neutrophils** and **parakeratosis** (retained nuclei in the stratum corneum), but not multinucleated giant cells. * The primary pathology in psoriasis involves **epidermal hyperplasia** and inflammation, distinct from viral cytopathic effects. *Molluscum contagiosum infection* * Tzanck smears from molluscum contagiosum lesions reveal characteristic **molluscum bodies** (large eosinophilic intracytoplasmic inclusion bodies) within epithelial cells. * These inclusion bodies are distinctive for the **poxvirus** infection and are not multinucleated giant cells. *Pemphigus vulgaris* * A Tzanck smear in pemphigus vulgaris demonstrates **acantholytic cells** (rounded-up epidermal cells that have lost their adhesion to one another) due to autoantibody-mediated breakdown of desmosomes. * While acantholysis is present, the key differentiating feature is the *absence* of multinucleated giant cells, as it is an autoimmune blistering disease, not a viral one.

Practice by Chapter

Herpes Simplex Virus Infections

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Varicella-Zoster Virus Infections

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Human Papillomavirus Infections

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Molluscum Contagiosum

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Viral Exanthems

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Hand, Foot, and Mouth Disease

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Orf and Milker's Nodule

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Cytomegalovirus Cutaneous Manifestations

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Epstein-Barr Virus Manifestations

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Poxvirus Infections

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HIV-Related Dermatoses

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Viral Infections in Immunocompromised Hosts

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