Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 181: Warthin-Finkeldey cells are found in:

A. Molluscum contagiosum
B. Herpes simplex infection
C. Measles (Correct Answer)
D. Mumps

Explanation: ***Measles*** - **Warthin-Finkeldey cells** are characteristic large, multinucleated giant cells found in lymphoid tissues during the **prodromal phase** of **measles infection** [1]. - These cells contain **multiple overlapping nuclei** (up to 100 nuclei) arranged in a distinctive pattern and are a key diagnostic histological feature of measles. - They are found in hyperplastic lymphoid tissues such as tonsils, adenoids, lymph nodes, appendix, and Peyer's patches. *Molluscum contagiosum* - This viral infection causes distinctive dome-shaped, flesh-colored papules with a central umbilication [2], but it is characterized by **molluscum bodies**, which are large eosinophilic intracytoplasmic inclusion bodies within infected keratinocytes. - It does not involve the formation of Warthin-Finkeldey cells. *Herpes simplex infection* - Herpes simplex virus (HSV) infections are characterized by **Tzanck cells**, which are multinucleated giant cells with **nuclear molding** and **eosinophilic intranuclear inclusion bodies** [3]. - Warthin-Finkeldey cells are not seen in HSV infections. *Mumps* - Mumps is a viral infection primarily affecting the salivary glands, particularly the parotid glands, and does not typically involve the formation of Warthin-Finkeldey cells in lymphoid tissue. - Its pathological features are mainly related to **inflammation and edema** of the affected glands. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 362-363. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1177-1178. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366.

Question 182: Warthin-Finkeldey giant cells are seen in:

A. Mumps virus infection
B. Rubella virus infection
C. Poliovirus infection
D. Measles virus infection (Correct Answer)

Explanation: ***Measles virus infection*** - **Warthin-Finkeldey giant cells** are characteristic large, multinucleated cells found in lymphoid tissues during the prodromal and early eruptive stages of **measles**. [1] - These cells are formed by the fusion of infected lymphocytes and are a hallmark of **measles-induced immunosuppression**. *Mumps virus infection* - Mumps typically causes nonsuppurative inflammation of the **salivary glands**, especially the parotid glands. - While it can form giant cells, they are generally not the specific Warthin-Finkeldey type associated with lymphoid tissue in measles. *Rubella virus infection* - Rubella, or German measles, is a milder disease characterized by a maculopapular rash and **lymphadenopathy**. - It does not specifically form Warthin-Finkeldey giant cells. *Poliovirus infection* - Poliovirus primarily affects the central nervous system, leading to **paralysis** by destroying motor neurons. - It does not cause the formation of Warthin-Finkeldey giant cells in lymphoid tissue. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 362-363.

Question 183: Which of the following does not have a viral etiology?

A. Hepatocellular carcinoma
B. Nasopharyngeal carcinoma
C. Colorectal adenocarcinoma
D. Breast ductal carcinoma (Correct Answer)

Explanation: ***Hodgkin's lymphoma*** - Hodgkin's lymphoma is primarily associated with **genetic factors** and environmental triggers instead of a viral cause [1][2]. - It can arise from **Reed-Sternberg cells**, which are not related to viral infections [1][2]. - EBV is not associated with certain subtypes of Hodgkin lymphoma [3]. *Nasopharyngeal carcinoma* - Strongly linked to **Epstein-Barr virus (EBV)**, which plays a significant role in its pathogenesis. - It is characterized by **nasal obstruction** and symptoms related to tumor invasion, with a clear viral etiology. *Hepatocellular carcinoma* - Often associated with **hepatitis B and C viruses**, which are well-known risk factors for liver cancer. - Chronic infection leads to **cirrhosis**, predisposing individuals to carcinoma development. *Burkitt's lymphoma* - Associated with **EBV**, particularly in endemic forms in Africa, affecting the jaw or abdomen [4]. - It involves **aggressive B-cell proliferation**, strongly linked to viral infection [4]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 556-557. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 614-616. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 618. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 335-336.

Question 184: Bodies characteristic of chromoblastomycosis, also known as Medlar bodies, are typically found in which of the following?

A. Asteroid bodies
B. Torres bodies
C. Sclerotic bodies (Correct Answer)
D. Guarnieri bodies

Explanation: #### ***Sclerotic bodies*** * These are **dark brown, spherical, thick-walled fungi cells** that divide by septation, rather than budding. * They are often referred to as **Medlar bodies** or **muriform cells**, and their presence is diagnostic of **chromoblastomycosis**. #### *Asteroid bodies* * These are **eosinophilic star-like structures** found in granulomas, typically seen in **sporotrichosis** around fungal cells. * They are formed by the deposition of **antigen-antibody complexes** and host proteins on the surface of the fungal organism. #### *Torres bodies* * These are **eosinophilic intracytoplasmic inclusions** found in the neurons of the **hippocampus** and **cerebellum** in cases of **rabies**. * Their presence is a definitive diagnostic feature of rabies in affected brain tissue. #### *Guarnieri bodies* * These are **eosinophilic intracytoplasmic inclusions** seen in cells infected with **variola (smallpox) virus**. * They are characteristic of **poxvirus infections** and represent viral factories where replication occurs.

Question 185: Which of the following is the MOST CHARACTERISTIC histopathological feature of paracoccidioidomycosis?

A. It is also known as South American blastomycosis.
B. Itraconazole is the treatment of choice.
C. It is a dimorphic fungus.
D. It shows a 'Mickey mouse' appearance on histopathological examination. (Correct Answer)

Explanation: ***It shows a 'Mickey mouse' appearance on histhopathological examination.*** - On histopathological examination, **Paracoccidioides brasiliensis** often presents with a characteristic "mickey mouse" or "mariner's wheel" appearance due to its **multiple budding cells**, which are large and refractile. - This distinctive morphology is a key microscopic feature for identifying the fungus in tissue samples. *It is also known as South American blastomycosis.* - While paracoccidioidomycosis is endemic to South and Central America, the term **"South American blastomycosis" is often reserved for paracoccidioidomycosis** and is a synonym rather than a histopathological feature. - This statement describes the geographical context and an alternative name for the disease, not its microscopic appearance. *Itraconazole is the treatment of choice.* - **Itraconazole is indeed the preferred treatment** for paracoccidioidomycosis, especially for less severe cases. - However, this statement refers to the therapeutic management of the disease, not a histopathological characteristic observable under a microscope. *It is a dimorphic fungus.* - **Paracoccidioides brasiliensis is a dimorphic fungus**, meaning it exists in different forms depending on temperature—as a mold in the environment and as yeast in human tissue [1]. - This describes the general biological classification of the fungus, not a specific, highly characteristic histopathological feature that differentiates it from other dimorphic fungi. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 393-394.

Question 186: Mouse-nibbled vocal cords are seen in which condition?

A. Leprosy
B. Laryngeal papilloma
C. Epiglottitis
D. Tuberculosis (Correct Answer)

Explanation: ***Tuberculosis*** - **Laryngeal tuberculosis** can cause irregular, eroded, and edematous vocal cords, often described as having a **"mouse-nibbled"** appearance due to granular ulcerations [1]. - This characteristic appearance is due to the chronic inflammatory and destructive nature of **Mycobacterium tuberculosis** infection on the laryngeal mucosa [1]. *Leprosy* - **Laryngeal leprosy** can cause diffuse infiltration, nodules, and thickening of the vocal cords, but typically does not present with the specific **"mouse-nibbled"** appearance of erosions [2]. - The lesions tend to be more nodular and less ulcerative in nature compared to tuberculosis [2]. *Laryngeal papilloma* - **Laryngeal papillomas** are benign tumors that present as wart-like growths on the vocal cords, often appearing as **mulberry-like** or **cauliflower-like** lesions [1]. - They do not typically cause the irregular, eroded, or "mouse-nibbled" pattern associated with tuberculosis. *Epiglottitis* - **Epiglottitis** is an acute inflammation of the epiglottis, primarily characterized by a **cherry-red, swollen epiglottis** and surrounding structures [1]. - While it can cause airway obstruction, it does not involve the characteristic erosions or "mouse-nibbled" appearance of the vocal cords [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 745-746. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 385-386.

Question 187: Owl eye intranuclear inclusion bodies are seen in?

A. Herpes zoster
B. Herpes simplex
C. CMV (Correct Answer)
D. EBV

Explanation: ***CMV*** - **Cytomegalovirus (CMV) infection** is classically associated with the presence of **"owl's eye" inclusions**, which are large, eosinophilic **intranuclear inclusions** surrounded by a clear halo, and smaller basophilic **intracytoplasmic inclusions** in infected cells [1]. - These characteristic inclusions are visible on **histopathological examination** of tissue samples from affected organs like the lung, gastrointestinal tract, or retina [1]. - The **owl's eye appearance** is pathognomonic for CMV infection and represents viral replication within the nucleus. *Herpes zoster* - Herpes zoster, caused by the **varicella-zoster virus (VZV)**, typically presents with **Cowdry type A intranuclear inclusions**, which are distinctly different from owl's eye inclusions [2]. - These inclusions show **eosinophilic cores with peripheral chromatin margination** and are seen in infected skin lesions and ganglionic neurons [2]. *Herpes simplex* - **Herpes simplex virus (HSV)** also produces **Cowdry type A intranuclear inclusions**, similar to VZV, characterized by chromatin margination and an eosinophilic core [3]. - These inclusions are indicative of **viral replication** in epithelial cells and neurons but lack the characteristic "owl's eye" appearance with clear halo seen in CMV [3]. *EBV* - **Epstein-Barr virus (EBV)** is primarily associated with **lymphoproliferative disorders** and **infectious mononucleosis**. - EBV infects B lymphocytes but does not produce discrete **cytomegalic inclusions** or "owl's eye" intranuclear inclusions on histopathology. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 367-368. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366.

Question 188: A patient presents with a viral infection that shows intranuclear inclusions in epithelial cells on biopsy. Which virus is most likely responsible?

A. Cytomegalovirus (CMV)
B. Herpes simplex virus (HSV) (Correct Answer)
C. Varicella-zoster virus (VZV)
D. Epstein-Barr virus (EBV)

Explanation: ***Herpes simplex virus (HSV)*** - HSV infection characteristically produces **intranuclear inclusions (Cowdry type A)** and **multinucleated giant cells** in infected epithelial cells [1] - In routine clinical practice, **HSV is the most commonly encountered** virus causing intranuclear inclusions in epithelial cell biopsies - These pathological findings are key for diagnosing HSV infections from mucocutaneous lesions [1] *Cytomegalovirus (CMV)* - CMV does cause prominent intranuclear inclusions in epithelial cells, but characteristically shows the **"owl's eye" appearance** with both large intranuclear inclusions AND prominent cytoplasmic inclusions - Since the question describes only intranuclear inclusions without mentioning the distinctive owl's eye pattern, CMV is less likely - CMV is more commonly seen in immunocompromised patients *Varicella-zoster virus (VZV)* - VZV also produces **intranuclear inclusions (Cowdry type A)** and multinucleated giant cells similar to HSV [2] - However, **HSV is more frequently encountered** in routine epithelial biopsies than VZV - Clinical context and distribution of lesions help differentiate between HSV and VZV [2] *Epstein-Barr virus (EBV)* - EBV primarily infects **B lymphocytes** and oropharyngeal epithelial cells - Unlike other herpesviruses, EBV does **not typically produce characteristic intranuclear inclusions** visible on routine epithelial biopsies - EBV's pathological hallmark is atypical lymphocytosis, not epithelial cytopathic effects **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.

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Healthcare-Associated Infections

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Infectious Disease Pathology in Immunocompromised Hosts

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Laboratory Diagnosis of Infections

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Antimicrobial Resistance

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