Infectious Diseases Practice Questions

Q: The histological feature known as 'Mickey Mouse Ears' is characteristically seen in:

Paracoccidioidomycosis. ***Paracoccidioidomycosis*** - This characteristic appearance, often described as a **"ship's wheel"** or **"Mickey Mouse ears"**, refers to the multiple budding yeast cells seen in **Paracoccidioides brasiliensis** on histological examination. - The central mother cell has several smaller daughter buds emerging from its periphery, resembling the iconic Mickey Mouse ears. *Candidiasis* - **Candida** infections typically manifest as **pseudohyphae** and **budding yeast** cells, but they do not form the multi-budding, "Mickey Mouse ears" configuration [1]. - The budding of Candida is usually singular or in short chains, distinct from the broad-based multi-budding of Paracoccidioides [1]. *Tuberculosis* - **Tuberculosis** is caused by **Mycobacterium tuberculosis**, a bacterium, and is characterized histologically by **granulomas** with caseous necrosis. - It does not involve yeast forms or the "Mickey Mouse ears" morphology. *Leptospirosis* - **Leptospirosis** is a **bacterial infection** caused by **Leptospira interrogans**, a spirochete, which is seen as spiral-shaped bacteria under microscopy. - This disease affects various organs and is not associated with fungal yeast forms or the "Mickey Mouse ears" appearance. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 736-737.

Q: Which of the following is the most predominant constituent of sulfur granules in Actinomycosis?

Organisms. ***Organisms*** - The characteristic "sulfur granules" in **Actinomycosis** are macroscopic colonies of the **Actinomyces bacteria** themselves. - These granules are formed by a dense tangled mass of bacterial filaments surrounded by host inflammatory cells. *Neutrophils and monocytes* - While **neutrophils** and other inflammatory cells are attracted to the site of infection and surround the bacterial colonies [1], [3], they are not the primary constituent of the granule itself. - They represent the host's immune response to the bacterial presence [1]. *Monocytes and lymphocytes* - **Monocytes** differentiate into macrophages that help in clearing infection, and **lymphocytes** are involved in specific immune responses [2]. - However, similar to neutrophils, these cells are part of the host's inflammatory response and not the main structural component of the sulfur granule [2], [3]. *Eosinophils* - **Eosinophils** are typically associated with parasitic infections and allergic reactions [3]. - They are not a predominant component of the sulfur granules found in bacterial infections like Actinomycosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 360. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 360-362. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 195-196.

Q: Warthin-Finkeldey giant cells in lymphoid tissue are characteristic of which of the following infections?

Measles infection. ***Measles infection*** - **Warthin-Finkeldey giant cells** are prominent multinucleated giant cells characteristic of lymphoid tissue changes in **measles (rubeola)** [1]. - These cells contain both eosinophilic nuclear and cytoplasmic inclusions and are crucial for the histological diagnosis of measles [1]. *Mumps infection* - Mumps primarily causes inflammation of the **parotid glands** but does not typically produce Warthin-Finkeldey giant cells in lymphoid tissue. - While mumps is also caused by a paramyxovirus, its histopathological features differ significantly from measles. *Congenital cytomegalovirus infection* - Characterized by the presence of large cells with prominent **intranuclear and intracytoplasmic inclusions** (owl's eye inclusions), especially in visceral organs. - It does not involve Warthin-Finkeldey giant cells in lymphoid tissues. *HIV infection* - HIV infection causes lymphoid depletion, germinal center hyperplasia followed by involution, and is associated with various opportunistic infections and lymphomas [1]. - It does not typically present with Warthin-Finkeldey giant cells in lymphoid tissue; these are specific to measles. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 362-363.

Q: Warthin-Finkeldey cells are found in:

Measles. ***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.

Q: Warthin-Finkeldey giant cells are seen in:

Measles virus infection. ***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.

Q: Owl eye intranuclear inclusion bodies are seen in?

CMV. ***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.

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

Herpes simplex virus (HSV). ***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.

Question 1

The histological feature known as 'Mickey Mouse Ears' is characteristically seen in:

Accepted Answer

Paracoccidioidomycosis

Answer

Tuberculosis

Answer

Candidiasis

Answer

Leptospirosis

Question 2

What are the histological characteristics of Lepra cells in lepromatous leprosy?

Accepted Answer

Foamy macrophages (Histiocytes)

Answer

Neutrophils

Answer

Plasma cells

Answer

Epithelioid cells

Question 3

Which of the following is the most predominant constituent of sulfur granules in Actinomycosis?

Accepted Answer

Organisms

Answer

Monocytes and lymphocytes

Answer

Neutrophils and monocytes

Answer

Eosinophils

Question 4

Skin lesions in meningococcal meningitis are due to

Accepted Answer

Endotoxin

Answer

Direct vascular damage

Answer

Bacterial exotoxin

Answer

Immune-mediated reaction

Question 5

Warthin-Finkeldey giant cells in lymphoid tissue are characteristic of which of the following infections?

Accepted Answer

Measles infection

Answer

Mumps infection

Answer

Congenital cytomegalovirus infection

Answer

HIV infection

Question 6

Warthin-Finkeldey cells are found in:

Accepted Answer

Measles

Answer

Molluscum contagiosum

Answer

Herpes simplex infection

Answer

Mumps

Question 7

Warthin-Finkeldey giant cells are seen in:

Accepted Answer

Measles virus infection

Answer

Mumps virus infection

Answer

Rubella virus infection

Answer

Poliovirus infection

Question 8

Which of the following is the MOST CHARACTERISTIC histopathological feature of paracoccidioidomycosis?

Accepted Answer

It shows a 'Mickey mouse' appearance on histopathological examination.

Answer

It is also known as South American blastomycosis.

Answer

Itraconazole is the treatment of choice.

Answer

It is a dimorphic fungus.

Question 9

Owl eye intranuclear inclusion bodies are seen in?

Accepted Answer

CMV

Answer

Herpes zoster

Answer

Herpes simplex

Answer

EBV

Question 10

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

Accepted Answer

Herpes simplex virus (HSV)

Answer

Cytomegalovirus (CMV)

Answer

Varicella-zoster virus (VZV)

Answer

Epstein-Barr virus (EBV)

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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