Immunopathology Practice Questions

Q: A patient presents with a history of episodic painful edema of the face and larynx, associated with abdominal pain, particularly during periods of stress. Which of the following is likely to be deficient?

C1 Esterase Inhibitor. **Explanation:** The clinical presentation of episodic, non-pitting edema of the face, larynx, and gastrointestinal tract (causing abdominal pain) triggered by stress or trauma is classic for **Hereditary Angioedema (HAE)**. **Why C1 Esterase Inhibitor is correct:** HAE is caused by an autosomal dominant deficiency or dysfunction of the **C1 esterase inhibitor (C1-INH)**. C1-INH normally regulates the classical complement pathway and the kinin system. Its deficiency leads to the uncontrolled activation of C1 and the kallikrein-kinin cascade. This results in excessive production of **Bradykinin**, a potent vasodilator that increases vascular permeability [1], leading to the characteristic angioedema. **Why other options are incorrect:** * **Complement C3/C5:** Deficiency of these late-pathway components typically presents with increased susceptibility to pyogenic bacterial infections (C3) or disseminated Neisserial infections (C5-C9). They do not cause angioedema. * **Properdin:** This is a positive regulator of the alternative pathway. Its deficiency is X-linked and predisposes individuals to severe meningococcal disease. **High-Yield NEET-PG Pearls:** * **Diagnosis:** Screening shows **low C4 levels** (even between attacks) because C1-INH cannot stop C1 from consuming C4. C1 levels remain normal. * **Management:** Acute attacks are treated with C1-INH concentrate or **Icatibant** (Bradykinin B2 receptor antagonist). * **Contraindication:** **ACE inhibitors** are strictly contraindicated in these patients as they prevent bradykinin breakdown, potentially triggering a fatal laryngeal edema. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 100-101.

Question 1

Hematoxylin bodies are seen in which of the following conditions?

Accepted Answer

Systemic Lupus Erythematosus (SLE)

Answer

Polyarteritis Nodosa (PAN)

Answer

Disseminated Intravascular Coagulation (DIC)

Answer

Wegener's Granulomatosis

Question 2

Which of the following statements regarding Wiskott-Aldrich syndrome is TRUE?

Accepted Answer

Associated with WASP gene mutation.

Answer

Primary defect is a B cell defect.

Answer

Primary defect is a T cell defect.

Answer

Defect in phagocytosis.

Question 3

A 12-year-old boy presents with a 5-day history of sore throat. His temperature is 38.7°C (103°F). Physical examination reveals inflamed tonsils and swollen cervical lymph nodes. Trafficking and recirculation of blood-borne lymphocytes through the cervical lymph nodes in this patient occurs primarily at which of the following locations?

Accepted Answer

High endothelial venules

Answer

Afferent lymphatic vessel

Answer

Efferent lymphatic vessel

Answer

Hassall corpuscles

Question 4

Severe combined immunodeficiency is seen with which precursor cell type?

Accepted Answer

Both Pre-B and Pre-T cells

Answer

Pre-B cell

Answer

Pre-T cell

Answer

NK cell precursor

Question 5

Which of the following is found in DiGeorge syndrome?

Accepted Answer

Tetany

Answer

Eczema

Answer

Total absence of T cells

Answer

Absent B and T cells

Question 6

Myasthenia gravis is associated with which of the following?

Accepted Answer

Thymoma

Answer

Hypergammaglobulinemia

Answer

Squamous cell carcinoma

Answer

Hepatic adenoma

Question 7

What condition is characterized by the pathognomonic lesion known as a tophus?

Accepted Answer

Gout

Answer

Multiple myeloma

Answer

Cystinosis

Answer

Eale's disease

Question 8

Which immunoglobulin has the highest molecular weight?

Accepted Answer

IgM

Answer

IgG

Answer

IgA

Answer

IgD

Question 9

Graft between members of the same species but of different genetic constitution is known as:

Accepted Answer

Allograft

Answer

Xenograft

Answer

Autograft

Answer

Isograft

Question 10

A patient presents with a history of episodic painful edema of the face and larynx, associated with abdominal pain, particularly during periods of stress. Which of the following is likely to be deficient?

Accepted Answer

C1 Esterase Inhibitor

Answer

Complement C3

Answer

Complement C5

Answer

Properidin

Immunopathology — MCQs

Immunopathology — MCQs

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