Immunology and Allergies — MCQs

Immunology and Allergies Indian Medical PG Practice Questions and MCQs

Question 91: A child presents with blotchy rash on legs, back and buttocks. All are true about the condition except:

A. Crops of palpable purpura
B. Small vessel vasculitis
C. Nephritis
D. Low platelets (Correct Answer)

Explanation: ***Low platelets*** - The rash described, characterized by blotchy purpura on the legs, back, and buttocks in a child, is highly suggestive of **Henoch-Schönlein purpura (HSP)**, now known as **IgA vasculitis**. - A key diagnostic feature of IgA vasculitis (HSP) is that it is a **non-thrombocytopenic purpura**, meaning **platelet counts are typically normal**; therefore, low platelets would be an incorrect statement regarding this condition. *Crops of palpable purpura* - **Palpable purpura** is the hallmark cutaneous manifestation of IgA vasculitis and is seen in nearly all cases, resulting from inflammation and bleeding from small vessels. - The rash typically occurs in successive "crops" on dependent areas like the **legs, buttocks, and elbows**. *Small vessel vasculitis* - IgA vasculitis is a classic example of a **small vessel vasculitis**, characterized by IgA immune complex deposition in the walls of small blood vessels. - This immune complex deposition leads to inflammation and damage of capillaries, venules, and arterioles. *Nephritis* - **Renal involvement**, specifically nephritis, is a significant complication of IgA vasculitis, occurring in a substantial proportion of patients. - It can manifest as **hematuria, proteinuria**, and potentially progress to renal failure, requiring close monitoring.

Question 92: Which of the following are causes of secondary immunodeficiency in children? I. Diphenylhydantoin II. Severe malnutrition III. Post-varicella state IV. Nephrotic syndrome Select the correct answer using the code given below :

A. II, III and IV
B. I, III and IV
C. I, II and III
D. I, II and IV (Correct Answer)

Explanation: ***I, II and IV*** - **Diphenylhydantoin (phenytoin)**, an anticonvulsant, causes immunosuppression through multiple mechanisms including IgA deficiency, hypogammaglobulinemia, and impaired T-cell function, making it a well-documented cause of drug-induced secondary immunodeficiency. - **Severe malnutrition** is one of the most common causes of secondary immunodeficiency worldwide, significantly impairing both cellular and humoral immunity by affecting T cells, B cells, and phagocytic function. - **Nephrotic syndrome** causes loss of immunoglobulins (particularly IgG) in the urine due to increased glomerular permeability, directly resulting in hypogammaglobulinemia and increased susceptibility to encapsulated bacterial infections (especially *Streptococcus pneumoniae*). *II, III and IV* - While **severe malnutrition**, **post-varicella state**, and **nephrotic syndrome** are all causes of immunodeficiency, this option incorrectly excludes diphenylhydantoin. - **Diphenylhydantoin** is a well-established cause of secondary immunodeficiency, not a minor or questionable cause. *I, III and IV* - This option incorrectly excludes **severe malnutrition**, which is one of the most important and prevalent causes of secondary immunodeficiency in children globally. - Severe malnutrition affects multiple components of the immune system and is considered a primary cause in pediatric populations. *I, II and III* - While **diphenylhydantoin**, **severe malnutrition**, and **post-varicella state** can all affect immunity, this option incorrectly excludes **nephrotic syndrome**. - The **post-varicella state** causes transient T-cell lymphopenia, but this is typically temporary and self-limited compared to the sustained immunoglobulin loss in nephrotic syndrome. - **Nephrotic syndrome** represents a more consistent and clinically significant cause of secondary immunodeficiency with a clear mechanism (protein loss in urine).

Question 93: Eight months old child had history of unusual crying and convulsions following previous vaccination after BCG, DPT & OPV ( first dose), and Hepatitis B. Now parents have brought child for next doses of vaccination. Which vaccine is contraindicated in this situation?

A. DT
B. Measles
C. Hepatitis B
D. DPT (Correct Answer)

Explanation: ***DPT*** - A history of **unusual crying** and **convulsions** after a previous DPT (first dose) is a contraindication for further doses of the pertussis component, necessitating the use of **DT (Diphtheria Tetanus)** without the pertussis component. - The **whole-cell pertussis (wP)** vaccine is particularly associated with such neurological adverse events, leading to the recommendation to avoid subsequent doses in such cases. *DT* - **DT (Diphtheria and Tetanus)** is actually the recommended alternative in this scenario, as it removes the pertussis component which is linked to the previous adverse neurological event. - It provides continued protection against diphtheria and tetanus without the risk associated with the **pertussis vaccine component**. *Measles* - **Measles vaccine** is a live attenuated viral vaccine and is not contraindicated by a history of convulsions or unusual crying following DPT. - The adverse reactions described are not typically associated with the measles vaccine and therefore would not prevent its administration. *Hepatitis B* - There is no contraindication for administering the **Hepatitis B vaccine** based on the described history of unusual crying and convulsions post-DPT. - The **Hepatitis B vaccine** is an inactivated vaccine and its adverse effect profile does not include such neurological events attributed to the DPT vaccine.

Question 94: A 10-year-old boy presents with fever, joint pain, and a lesion over his hand, as seen in the image below. Which of the following is the clinical finding, and what is the likely diagnosis?

A. Malar rash - Systemic lupus erythematosus
B. Heliotrope rash - Dermatomyositis
C. Erythema multiforme - Stevens-Johnson syndrome
D. Gottron's papules - Juvenile dermatomyositis (Correct Answer)

Explanation: ***Gottron's papules - Juvenile dermatomyositis*** - The image clearly displays **Gottron's papules**, which are **erythematous, scaling papules** symmetrically distributed over the **dorsal aspects of the interphalangeal joints** (MCP and PIP joints). - The clinical presentation of a 10-year-old boy with **fever, joint pain**, and these characteristic skin lesions is highly indicative of **juvenile dermatomyositis (JDM)**, an inflammatory myopathy. *Malar rash - Systemic lupus erythematosus* - A **malar rash** is a common finding in **systemic lupus erythematosus (SLE)**, but it typically presents as an **erythematous rash over the cheeks and bridge of the nose**, sparing the nasolabial folds, and does not exhibit the papular, scaly appearance over the knuckles seen in the image. - While SLE can cause fever and joint pain, the specific skin lesion depicted is not consistent with a malar rash. *Heliotrope rash - Dermatomyositis* - A **heliotrope rash** is another classic skin manifestation of **dermatomyositis**, characterized by a **purplish discoloration around the eyelids**, often accompanied by periorbital edema. - This is distinct from the lesions shown on the knuckles, which are diagnostic of Gottron's papules, not a heliotrope rash. *Erythema multiforme - Stevens-Johnson syndrome* - **Erythema multiforme** is characterized by **targetoid lesions** with concentric rings, often appearing acutely in response to infections or medications. - **Stevens-Johnson syndrome (SJS)** is a severe form of erythema multiforme, involving extensive epidermal detachment and mucosal involvement, which does not match the chronic-appearing, papular lesions on the knuckles in the image.

Question 95: In which of the following disorders, vaccines are not contraindicated in the person suffering from that disease?

A. Digeorge syndrome
B. Wiskott Aldrich syndrome
C. Ataxia telangiectasia
D. Complement deficiency disorders (Correct Answer)

Explanation: ***Complement deficiency disorders*** - While patients with **complement deficiencies** are susceptible to certain infections (especially by encapsulated bacteria), their adaptive immune system is generally intact. - Therefore, most vaccines, including **live attenuated vaccines**, are not contraindicated; in fact, vaccination is crucial for preventing infections in these patients. *Digeorge syndrome* - This syndrome involves **thymic hypoplasia or aplasia**, leading to severe **T-cell immunodeficiency**. - **Live attenuated vaccines** (e.g., MMR, varicella) are contraindicated due to the risk of uncontrolled replication of the vaccine strain in immunocompromised individuals. *Wiskott Aldrich syndrome* - This is an **X-linked immunodeficiency** characterized by immunodeficiency, eczema, and thrombocytopenia, involving defects in both T and B cell function, and **platelet dysfunction**. - Due to profound immune defects, particularly in T-cell function, **live attenuated vaccines** are contraindicated. *Ataxia telangiectasia* - This is an autosomal recessive disorder causing **progressive cerebellar ataxia**, telangiectasias, and severe **combined immunodeficiency (SCID)-like features** affecting both T and B cells, as well as an increased risk of malignancy. - Due to the severe immunodeficiency, **live attenuated vaccines** are contraindicated.

Question 96: A 10 year old male child presents with purpuric rashes on the lower extremities, hematuria, abdominal pain, and arthritis but has no history of fever. What is the likely diagnosis ?

A. Hemolytic uremic syndrome
B. Idiopathic thrombocytopenic purpura
C. Meningococcal meningitis
D. Henoch-Schonlein purpura (Correct Answer)

Explanation: ***Henoch-Schonlein purpura*** - **Henoch-Schonlein purpura (HSP)** is a **vasculitis** characterized by the classic tetrad of palpable **purpura**, **abdominal pain**, **arthralgia**, and **renal involvement** (hematuria). - The child's presentation, including purpuric rashes on lower extremities, hematuria, abdominal pain, and arthritis, fits the criteria for HSP, which typically affects children. - The **absence of fever** helps distinguish HSP from infectious causes like meningococcemia. *Hemolytic uremic syndrome* - **Hemolytic uremic syndrome (HUS)** is characterized by a triad of **hemolytic anemia**, **thrombocytopenia**, and **acute kidney injury**. - While there is renal involvement (hematuria), the prominent purpuric rash and arthritis point away from HUS as the primary diagnosis. *Idiopathic thrombocytopenic purpura* - **Idiopathic thrombocytopenic purpura (ITP)** involves isolated **thrombocytopenia**, leading to increased bleeding and bruising (purpura). - It does not typically cause the significant abdominal pain, arthritis, or gross hematuria observed in this patient. *Meningococcal meningitis* - **Meningococcal meningitis** is a severe bacterial infection characterized by fever, headache, stiff neck, and a rapidly progressing **petechial or purpuric rash**. - The absence of fever and meningeal signs, and the presence of prominent arthritis and hematuria, make meningococcal meningitis less likely.

Question 97: All are common features of juvenile idiopathic arthritis EXCEPT

A. Fever with rash
B. Hepatosplenomegaly
C. Rheumatoid factor positive (Correct Answer)
D. Increased ESR

Explanation: ***Rheumatoid factor positive*** - While some subtypes of **juvenile idiopathic arthritis (JIA)** can be **rheumatoid factor (RF) positive**, the majority of cases, especially the systemic and oligoarticular forms, are **RF negative**. Therefore, a positive RF is not a common feature overall. - The presence of **RF-positive JIA** typically indicates a polyarticular course similar to adult rheumatoid arthritis, but it's less prevalent in the broader JIA population. *Fever with rash* - **Systemic JIA** (Still's disease) is characterized by a high intermittent fever and a salmon-pink macular rash, making this a common feature in a significant subset of JIA. - This specific subtype often presents with prominent systemic inflammation rather than solely articular symptoms. *Hepatosplenomegaly* - **Hepatosplenomegaly** is a common systemic manifestation, particularly in **systemic JIA**, indicating multi-organ involvement due to widespread inflammation. - Along with lymphadenopathy and serositis, it reflects the systemic nature of the disease in acutely ill children. *Increased ESR* - An **elevated erythrocyte sedimentation rate (ESR)** is a general marker of inflammation and is frequently observed across various subtypes of JIA. - This is a common finding in active disease due to the underlying inflammatory process affecting the joints and potentially other organs.

Question 98: Pauciarticular JRA is characterized by all except:

A. Scleritis (Correct Answer)
B. Uveitis
C. Keratopathy
D. Cataract

Explanation: ***Scleritis*** - **Scleritis** is a rare ocular manifestation in juvenile idiopathic arthritis (JIA) and is not a characteristic feature of **pauciarticular JRA**. - Its presence would suggest other systemic inflammatory conditions or more severe forms of JIA, but not typical pauciarticular JRA. *Uveitis* - **Uveitis**, specifically **chronic anterior uveitis**, is a common and often asymptomatic complication in pauciarticular JRA, particularly in ANA-positive girls. - Regular ophthalmologic screening is crucial for early detection and prevention of long-term vision impairment. *Keratopathy* - While not a direct primary manifestation, **keratopathy** (corneal disease) can occur as a secondary complication of chronic **uveitis** in pauciarticular JRA, often due to inflammation and prolonged use of corticosteroids. - Corneal band keratopathy, in particular, is associated with chronic anterior uveitis. *Cataract* - **Cataract formation** is a known complication associated with chronic **uveitis** in pauciarticular JRA, often exacerbated by long-term corticosteroid use. - It results from chronic inflammation affecting the lens of the eye and can lead to significant vision loss if untreated.

Question 99: Which of the following is not true about Juvenile rheumatoid arthritis?

A. Uveitis
B. Rheumatoid nodules
C. Fever
D. Raynaud's phenomenon (Correct Answer)

Explanation: ***Raynaud's phenomenon*** - While other conditions, like **systemic lupus erythematosus** or scleroderma, are associated with Raynaud's, it is **not a typical feature** of **juvenile idiopathic arthritis (JIA)**. - Raynaud's phenomenon is characterized by **vasospasm** of the small arteries and arterioles in response to cold or stress. *Uveitis* - **Uveitis** (inflammation of the uvea) is a common and serious extra-articular manifestation of **JIA**, particularly in the **oligoarticular** and **polyarticular subtypes**. - It often presents asymptomatically and can lead to significant vision loss if not detected and treated early. *Rheumatoid nodules* - **Rheumatoid nodules** can occur in a subset of JIA patients, particularly those with the **polyarticular rheumatoid factor-positive** subtype. - These are subcutaneous nodules found in areas of pressure, similar to those seen in adult rheumatoid arthritis. *Fever* - **Fever** is a hallmark symptom of the **systemic subtype** of JIA (Still's disease). - It typically presents as a **quotidian spiking fever**, often accompanied by an evanescent rash.

Question 100: A 3-month-old with recurrent infections and no thymus shadow has lymphopenia. What is the most likely enzyme deficiency?

A. HGPRT
B. Glucose-6-phosphatase
C. Pyruvate kinase
D. Adenosine deaminase (Correct Answer)

Explanation: ***Adenosine deaminase*** - **Adenosine deaminase (ADA)** deficiency is a hallmark cause of **severe combined immunodeficiency (SCID)**, characterized by profound B-cell and T-cell lymphopenia. - The absence of a **thymus shadow** on chest X-ray is a classic sign of T-cell developmental failure, highly suggestive of SCID, often due to ADA deficiency. *HGPRT* - Deficiency of **hypoxanthine-guanine phosphoribosyltransferase (HGPRT)** causes **Lesch-Nyhan syndrome**, which presents with **hyperuricemia**, neurological dysfunction, and self-mutilation. - It does not directly cause lymphopenia or thymic aplasia and is primarily a disorder of purine salvage rather than immune development. *Glucose-6-phosphatase* - **Glucose-6-phosphatase deficiency** leads to **Glycogen Storage Disease Type I (von Gierke disease)**, characterized by severe **fasting hypoglycemia**, lactic acidosis, hepatomegaly, and hyperlipidemia. - This enzyme deficiency is not associated with immunodeficiency, lymphopenia, or thymic abnormalities. *Pyruvate kinase* - **Pyruvate kinase deficiency** primarily affects red blood cells, causing **chronic hemolytic anemia** due to impaired glycolysis. - It is not associated with recurrent infections, lymphopenia, or T-cell deficiencies.

Practice by Chapter

Development of Immune System

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Primary Immunodeficiency Disorders

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Secondary Immunodeficiency Disorders

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Allergic Rhinitis

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Asthma in Children

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Atopic Dermatitis

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Food Allergies

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Drug Allergies

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Anaphylaxis

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Urticaria and Angioedema

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Autoimmune Disorders

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Immunotherapy

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