Question:medium
A young adult presents with facial pain and painful vesicular lesions in the mouth. Tzanck smear reveals multinucleated giant cells with intranuclear inclusions. What is the most likely causative organism?
A young adult presents with facial pain and painful vesicular lesions in the mouth. Tzanck smear reveals multinucleated giant cells with intranuclear inclusions. What is the most likely causative organism?
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Painful vesicles + multinucleated giant cells on Tzanck smear = HSV.
Updated On: May 14, 2026
- Adenovirus
- Cytomegalovirus
- EBV
- HSV
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Question:
The clinical features (painful oral vesicles) and the cytological findings (Tzanck smear with multinucleated giant cells) are classic for a herpesvirus infection.
Step 2: Detailed Explanation:
Clinical Presentation: Painful vesicles in the oral cavity in a young adult are most commonly caused by Herpes Simplex Virus Type 1 (HSV-1).
Tzanck Smear Findings:
Multinucleated Giant Cells: These are formed by the fusion of infected keratinocytes (Syncytia).
Cowdry Type A Inclusions: These are eosinophilic intranuclear inclusions found in HSV and VZV infections.
Analyzing the options:
HSV (D): Is the classic cause of painful grouped vesicles and gives a positive Tzanck smear.
CMV (B): Typically shows "Owl's eye" large single intranuclear inclusions and usually doesn't cause painful oral vesicles in immunocompetent adults.
Adenovirus (A): Causes pharyngoconjunctival fever but not vesicular lesions with multinucleated giant cells.
Step 3: Final Answer:
The presence of multinucleated giant cells on a Tzanck smear from oral vesicles is diagnostic of a Herpes Simplex Virus (HSV) infection.
The clinical features (painful oral vesicles) and the cytological findings (Tzanck smear with multinucleated giant cells) are classic for a herpesvirus infection.
Step 2: Detailed Explanation:
Clinical Presentation: Painful vesicles in the oral cavity in a young adult are most commonly caused by Herpes Simplex Virus Type 1 (HSV-1).
Tzanck Smear Findings:
Multinucleated Giant Cells: These are formed by the fusion of infected keratinocytes (Syncytia).
Cowdry Type A Inclusions: These are eosinophilic intranuclear inclusions found in HSV and VZV infections.
Analyzing the options:
HSV (D): Is the classic cause of painful grouped vesicles and gives a positive Tzanck smear.
CMV (B): Typically shows "Owl's eye" large single intranuclear inclusions and usually doesn't cause painful oral vesicles in immunocompetent adults.
Adenovirus (A): Causes pharyngoconjunctival fever but not vesicular lesions with multinucleated giant cells.
Step 3: Final Answer:
The presence of multinucleated giant cells on a Tzanck smear from oral vesicles is diagnostic of a Herpes Simplex Virus (HSV) infection.
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