Immunodeficiency Disorders — MCQs
Which immunoglobulin is most commonly associated with lymphoplasmacytic lymphoma (Waldenström macroglobulinemia)?
In primary immune deficiency, the following plasma protein fraction can be reduced:
Which of the following statements about Wiskott-Aldrich syndrome is false?
A 6-month-old male infant presents with recurrent severe bacterial infections with encapsulated organisms (Streptococcus pneumoniae and Haemophilus influenzae). Laboratory findings reveal profound deficiency of all immunoglobulin classes (IgG, IgA, IgM) with absent mature B cells in peripheral blood. The most likely diagnosis is:
t(2,8) is associated with:
Which of the following statements about MALToma is true?
Which of the following genetic syndromes are associated with brain tumours? 1. Neurofibromatosis type 1 2. Neurofibromatosis type 2 3. Tuberous sclerosis 4. Wiskott-Aldrich syndrome Select the answer using the code given below.
A 27-year-old man has surgery for a testicular mass. Histologic sections reveal the mass to be a testicular yolk sac tumor. Which of the substances listed below is most likely to be increased in this patient's serum?
Which of the following is NOT a disorder of phagocytosis?
Biopsy of the parotid gland in Sjogren’s syndrome shows which of the following inflammatory cells?
Immunodeficiency Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Which immunoglobulin is most commonly associated with lymphoplasmacytic lymphoma (Waldenström macroglobulinemia)?
- A. IgG
- B. IgM (Correct Answer)
- C. IgA
- D. IgE
Explanation: ***IgM*** - Plasmacytoid lymphomas are often characterized by elevated levels of **IgM**, which is commonly associated with this type of lymphoma [1][2]. - This association highlights the **role of IgM** in the pathophysiology of these lymphomas and their clinical manifestations [1][2]. *IgA* - IgA is primarily involved in mucosal immunity and is not a main feature of plasmacytoid lymphomas. - Elevated IgA levels are more associated with conditions like **IgA myeloma** rather than plasmacytoid lymphomas. *IgG* - IgG is the most abundant immunoglobulin but does not have a specific association with plasmacytoid lymphomas. - Conditions such as **multiple myeloma** can involve elevated IgG, making it distinct from plasmacytoid lymphomas. *IgE* - IgE is mainly involved in allergic reactions and **parasitic infections**, and is not typically linked to plasmacytoid lymphomas. - Its relevance is more in the context of **allergic disorders** than lymphoma types. **References:** [1] 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. 606-607, 609-610. [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. 606-607.
Question 2: In primary immune deficiency, the following plasma protein fraction can be reduced:
- A. Alpha2 globulin
- B. Gamma globulin (Correct Answer)
- C. Alpha1 globulin
- D. Beta globulin
Explanation: ***Gamma globulin*** - In primary immune deficiency, there is a significant reduction in **gamma globulin**, resulting from impaired antibody production [1]. - This protein fraction primarily contains **immunoglobulins**, which are crucial for the immune response [1][2]. *Alpha1 globulin* - Typically associated with **protease inhibitors** and **transport proteins**, its levels are not directly impacted in primary immune deficiency. - This fraction does not primarily play a role in the **immune response** like gamma globulins do. *Alpha2 globulin* - Contains **haptoglobin** and **ceruloplasmin**, which often remain stable in immunodeficiencies. - Its reduction is not characteristic of primary immune deficiency, as it does not directly relate to **antibody function**. *Beta globulin* - Includes fractions such as **transferrin** and **complement proteins**, generally unaffected by primary immune deficiencies. - While important, these proteins do not primarily comprise **antibodies** and do not show a decrease in these conditions.
Question 3: Which of the following statements about Wiskott-Aldrich syndrome is false?
- A. Autosomal Recessive disorder (Correct Answer)
- B. Impaired platelet aggregation in response to agonist
- C. Thrombocytopenia
- D. Eczematous Rash
Explanation: ***Autosomal Recessive disorder*** - **Wiskott-Aldrich Syndrome (WAS)** is an **X-linked recessive disorder**, not autosomal recessive. This statement is therefore false, making it the correct answer to the question. - It is caused by mutations in the WAS gene, which encodes the Wiskott-Aldrich syndrome protein (WASp) and is located on the X chromosome. *Eczematous Rash* - Patients with Wiskott-Aldrich syndrome frequently present with severe and persistent **eczematous rash**, which is a key component of the clinical triad. - This rash is often recalcitrant to standard treatments and can be widespread. *Impaired platelet aggregation in response to agonist* - Patients with WAS exhibit **abnormal platelet function**, specifically **impaired aggregation** in response to various agonists. - This functional defect contributes to the bleeding diathesis seen in the syndrome, alongside reduced platelet count. *Thrombocytopenia* - **Thrombocytopenia**, characterized by a low platelet count, is a hallmark feature of Wiskott-Aldrich syndrome. - The platelets are also typically very small in size (**microthrombocytopenia**), which is a distinctive finding.
Question 4: A 6-month-old male infant presents with recurrent severe bacterial infections with encapsulated organisms (Streptococcus pneumoniae and Haemophilus influenzae). Laboratory findings reveal profound deficiency of all immunoglobulin classes (IgG, IgA, IgM) with absent mature B cells in peripheral blood. The most likely diagnosis is:
- A. X-linked agammaglobulinemia of Bruton (Correct Answer)
- B. DiGeorge's syndrome
- C. Isolated IgA deficiency
- D. Chronic granulomatous disease
Explanation: ***X-linked agammaglobulinemia of Bruton*** - Characterized by a **severe deficiency of immunoglobulins**, leading to frequent bacterial infections in infants [1][2]. - The absence of mature B cells in the peripheral blood is a hallmark [1], along with a positive family history due to its **X-linked recessive inheritance** [2]. *Chronic granulomatous disease* - Presents with recurrent **bacterial and fungal infections** due to a defect in **immune response**, but not primarily characterized by low immunoglobulin levels. - Typically involves **catalase-positive organisms**, which differs from the broad antibody deficiency seen in the correct diagnosis. *Isolated IgA deficiency* - Commonly manifests with **sinus and respiratory infections**, but patients often have normal **IgG and IgM levels**. - It does not usually cause severe or recurrent infections in infants, differentiating it from the severe immunodeficiency seen in X-linked agammaglobulinemia. *DiGeorge's syndrome* - Associated with **congenital heart defects** and **thyroid issues**, along with T-cell deficiency, but typically presents with **low T-cell counts rather than low B cells or immunoglobulins**. - The immunological profile is distinct from that of X-linked agammaglobulinemia, where B cells are severely affected [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 248-249. [2] 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. 165-166.
Question 5: t(2,8) is associated with:
- A. T cell ALL
- B. CML
- C. B cell ALL (Correct Answer)
- D. CLL
Explanation: ***B cell ALL*** - The translocation **t(2;8)(p11;q24)** is a **variant cytogenetic abnormality** specifically associated with **Burkitt lymphoma/leukemia**, a highly aggressive form of mature B-cell neoplasm, which can present as B-cell ALL. [1] - This variant translocation (occurring in ~15% of Burkitt lymphoma cases) leads to the **dysregulation of the MYC oncogene** on chromosome 8q24 due to its juxtaposition with the **kappa (κ) immunoglobulin light chain gene (IGK)** on chromosome 2p11. [1] - The most common translocation in Burkitt lymphoma is **t(8;14)(q24;q32)** involving MYC and the immunoglobulin heavy chain gene IGH (~80% of cases), while **t(8;22)** involving the lambda light chain occurs in ~5% of cases. [1] *T cell ALL* - T-cell ALL is primarily associated with translocations involving **T-cell receptor genes (e.g., TCRα/δ on 14q11, TCRβ on 7q34)** and various oncogenes like *TAL1*, *LMO1*, *LMO2*, *HOXA*, and *NKX2-5*. - It does not typically involve the **t(2;8) translocation**. *CML* - **Chronic Myeloid Leukemia (CML)** is classically defined by the presence of the **Philadelphia chromosome**, an acquired reciprocal translocation **t(9;22)(q34;q11)**. - This translocation results in the formation of the **BCR-ABL1 fusion gene**, which encodes a constitutively active tyrosine kinase. *CLL* - **Chronic Lymphocytic Leukemia (CLL)** is most frequently associated with cytogenetic abnormalities such as **deletions of 13q14, 11q22-23 (ATM gene), and 17p13 (TP53 gene)**, and **trisomy 12**. - The **t(2;8) translocation** is not characteristic of CLL. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 324-325.
Question 6: Which of the following statements about MALToma is true?
- A. They are primary gastric lymphomas
- B. H. Pylori infection is a known risk factor (Correct Answer)
- C. They are a type of T cell lymphoma
- D. Exclusively seen in the gastric antrum
Explanation: ***H. Pylori infection is a risk factor*** - MALToma, or **mucosa-associated lymphoid tissue lymphoma**, is often associated with chronic **H. Pylori infection**, making it a significant risk factor [1]. - **Eradication of H. Pylori** can lead to regression of MALT lymphoma, further supporting the association. *They are a type of T cell lymphoma* - MALToma is classified as a **B-cell lymphoma**, primarily arising from **marginal zone B cells** [1]. - T-cell lymphomas differ significantly in their **pathophysiology** and typical clinical presentations. *They are secondary gastric lymphomas* - MALTomas typically arise **primarily** in the gastric mucosa rather than as secondary lymphomas from another site [1]. - Secondary lymphomas are usually related to more aggressive forms and are often associated with **systemic involvement**. *Commonly seen in gastric cardia* - MALTomas are most frequently found in the **stomach** but are not specifically concentrated in the **gastric cardia** region. - They can also manifest in other areas such as the **antrum**, making this statement misleading. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 356-358.
Question 7: Which of the following genetic syndromes are associated with brain tumours? 1. Neurofibromatosis type 1 2. Neurofibromatosis type 2 3. Tuberous sclerosis 4. Wiskott-Aldrich syndrome Select the answer using the code given below.
- A. 1, 2 and 3 (Correct Answer)
- B. 1, 3 and 4
- C. 1 and 2 only
- D. 2, 3 and 4
Explanation: ***1, 2 and 3*** - **Neurofibromatosis type 1 (NF1)**, **Neurofibromatosis type 2 (NF2)**, and **Tuberous sclerosis (TSC)** are all well-established genetic syndromes associated with an increased risk of developing various brain tumors [1]. - NF1 is linked to **optic pathway gliomas**, NF2 to **schwannomas** and **meningiomas**, and TSC to **subependymal giant cell astrocytomas (SEGAs)** [1], [2]. *1 and 2 only* - This option is incomplete as it correctly identifies NF1 and NF2 but omits Tuberous sclerosis, which is also strongly associated with brain tumours [1]. - While NF1 and NF2 are major genetic risk factors for brain tumors, excluding TSC would be an inaccurate representation of conditions linked to these abnormalities [1]. *1, 3 and 4* - This option incorrectly includes **Wiskott-Aldrich syndrome (WAS)**, which is an **immunodeficiency disorder** and not typically associated with primary brain tumours. - Although WAS can lead to an increased risk of lymphomas, these are generally not considered primary brain tumors [1] in the context of genetic syndromes predisposing to such growths. *2, 3 and 4* - This option again incorrectly includes **Wiskott-Aldrich syndrome** while omitting **Neurofibromatosis type 1**, a significant genetic syndrome linked to brain tumors [1]. - Omitting NF1, a condition known for an increased risk of gliomas, renders this option incomplete and inaccurate. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 724-725. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1319.
Question 8: A 27-year-old man has surgery for a testicular mass. Histologic sections reveal the mass to be a testicular yolk sac tumor. Which of the substances listed below is most likely to be increased in this patient's serum?
- A. Acid phosphatase
- B. Human chorionic gonadotropin
- C. Alkaline phosphatase
- D. Alpha-fetoprotein (Correct Answer)
Explanation: ***Alpha-fetoprotein*** - **Yolk sac tumors**, also known as endodermal sinus tumors, are characterized by the production and elevation of **alpha-fetoprotein (AFP)** [2]. - AFP levels are crucial for both the **diagnosis** and **monitoring** of treatment response in patients with yolk sac tumors [2]. *Acid phosphatase* - **Acid phosphatase** is primarily associated with **prostatic carcinoma**, particularly in bone metastases, and would not be elevated in a testicular yolk sac tumor. - While it can be found in other tissues, it is not a specific or sensitive marker for germ cell tumors. *Human chorionic gonadotropin* - **Human chorionic gonadotropin (hCG)** is primarily elevated in **choriocarcinoma** and some **seminomas**, but not typically in pure yolk sac tumors [1]. - Mixed germ cell tumors can have elevated hCG if they contain a choriocarcinomatous component [1]. *Alkaline phosphatase* - **Alkaline phosphatase (ALP)** is a marker often elevated in conditions affecting the **liver** (e.g., cholestasis) or **bones** (e.g., Paget's disease, osteoblastic activity), but not specifically associated with testicular yolk sac tumors. - It is a general enzyme involved in various metabolic processes and not a specific tumor marker for this type of cancer. **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. 512-513. [2] 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. 254-255.
Question 9: Which of the following is NOT a disorder of phagocytosis?
- A. Job's syndrome
- B. Chediak-Higashi syndrome
- C. Myeloperoxidase deficiency
- D. Wiskott-Aldrich syndrome (Correct Answer)
Explanation: The correct answer is **Wiskott-Aldrich syndrome (WAS)** because it is primarily a **combined B-cell and T-cell immunodeficiency**, not a primary disorder of phagocytosis [1]. It is an X-linked recessive condition caused by a mutation in the *WASP* gene, which affects the actin cytoskeleton in hematopoietic cells [1]. This leads to the classic triad of **Thrombocytopenia** (with small platelets), **Eczema**, and **Recurrent infections**. **Analysis of other options (Disorders of Phagocytosis):** * **Job’s Syndrome (Hyper-IgE Syndrome):** A defect in JAK-STAT signaling (STAT3 mutation) leading to impaired neutrophil chemotaxis. It is characterized by "Cold" staphylococcal abscesses, retained primary teeth, and high IgE. * **Chediak-Higashi Syndrome:** A defect in vesicle fusion (LYST gene mutation) [2]. It results in impaired phagolysosome formation [2]. Key findings include giant cytoplasmic granules in neutrophils and partial albinism [2]. * **Myeloperoxidase (MPO) Deficiency:** The most common inherited defect of phagocytes. It involves a failure to produce Hypochlorous acid (HOCl), though most patients remain asymptomatic unless they have co-existing diabetes (predisposing to *Candida* infections). **NEET-PG High-Yield Pearls:** 1. **Phagocytosis Steps:** Remember the sequence: Chemotaxis → Opsonization → Ingestion → Killing (Oxidative burst). 2. **Nitroblue Tetrazolium (NBT) Test:** Used for Chronic Granulomatous Disease (CGD); it remains **negative** (colorless) in CGD due to NADPH oxidase deficiency. 3. **Wiskott-Aldrich Mnemonic:** **TIE** (Thrombocytopenia, Infections, Eczema). 4. **Small Platelets:** WAS is one of the few conditions where platelet size is decreased on a peripheral smear. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 250-251. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 245-246.
Question 10: Biopsy of the parotid gland in Sjogren’s syndrome shows which of the following inflammatory cells?
- A. Neutrophils
- B. Eosinophils
- C. Basophils
- D. Lymphocytes (Correct Answer)
Explanation: **Explanation:** **Sjögren’s Syndrome (SS)** is a chronic autoimmune disorder characterized by the progressive destruction of exocrine glands, primarily the lacrimal and salivary glands [1]. **Why Lymphocytes are the Correct Answer:** The hallmark histopathological feature of Sjögren’s syndrome is **focal lymphocytic infiltration** of the glandular parenchyma [1],[3]. These infiltrates are predominantly composed of **CD4+ T-helper cells** and some B cells [1]. In the parotid gland, this intense lymphocytic infiltration leads to the formation of "epimyoepithelial islands" and the eventual destruction of the acini (atrophy), resulting in xerostomia (dry mouth) [3]. **Why Other Options are Incorrect:** * **A. Neutrophils:** These are markers of acute bacterial inflammation (e.g., acute sialadenitis). SS is a chronic autoimmune process, not an acute infection. * **B. Eosinophils:** These are typically associated with Type I hypersensitivity (allergic) reactions or parasitic infections, neither of which defines the pathology of SS. * **C. Basophils:** These are involved in systemic allergic responses and are rarely the dominant cell type in solid organ biopsies for autoimmune diseases. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Gold Standard:** A biopsy of the **minor salivary glands (lip biopsy)** is preferred over the parotid gland to confirm the diagnosis, looking for a "Focus Score" (≥1 focus of 50 lymphocytes per 4 $mm^2$). * **Serology:** Positive for **Anti-Ro (SS-A)** and **Anti-La (SS-B)** antibodies [1]. * **Malignancy Risk:** Patients with Sjögren’s syndrome have a **40-fold increased risk** of developing **B-cell Non-Hodgkin Lymphoma** (specifically MALToma) [2],[3]. * **Clinical Triad:** Dry eyes (keratoconjunctivitis sicca), dry mouth (xerostomia), and often an associated connective tissue disease (like Rheumatoid Arthritis). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 234-235. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 236. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 235-236.
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