Immunology and Allergies Practice Questions

Q: What is a characteristic feature of Systemic Juvenile Idiopathic Arthritis?

RA factor is negative. ### Explanation **Systemic Juvenile Idiopathic Arthritis (sJIA)**, also known as Still’s disease, is a unique subtype of JIA characterized by prominent extra-articular features. **Why the correct answer is right:** In sJIA, the **Rheumatoid Factor (RF) is characteristically negative**. Unlike the polyarticular subtype (which can be RF positive), sJIA is considered an autoinflammatory disease rather than a classic autoimmune disease. Diagnosis is clinical, based on the presence of arthritis in one or more joints associated with (or preceded by) a fever of at least 2 weeks' duration that is daily ("quotidian") for at least 3 days, accompanied by features like an evanescent salmon-pink rash, lymphadenopathy, or serositis. **Analysis of Incorrect Options:** * **A. Uveitis is a feature:** This is incorrect for sJIA. Chronic anterior uveitis is a classic complication of **Oligoarticular JIA** (especially if ANA positive). Uveitis is very rare in the systemic subtype. * **B. It occurs after 16 years of age:** By definition, JIA must have an onset **before the age of 16**. If similar symptoms occur after 16, it is termed Adult-Onset Still’s Disease (AOSD). * **C. NSAIDs are contraindicated:** This is false. NSAIDs are often the **first-line** symptomatic treatment for pain and fever in JIA, though systemic steroids or biologics (IL-1 and IL-6 inhibitors) are usually required for definitive control. **High-Yield Clinical Pearls for NEET-PG:** * **Fever Pattern:** Classic "Quotidian" fever (spikes once daily, usually in the evening, returning to baseline). * **Laboratory Markers:** Marked leukocytosis, thrombocytosis, and highly elevated ESR/CRP. * **Ferritin:** Extremely high ferritin levels are common and can signal the onset of **Macrophage Activation Syndrome (MAS)**, a life-threatening complication of sJIA. * **Biologics of Choice:** Tocilizumab (IL-6 inhibitor) and Anakinra/Canakinumab (IL-1 inhibitors).

Q: A child presents with delayed separation of the umbilical cord, leukocytosis, Down syndrome, and recurrent infections. What is the most likely diagnosis?

Leukocyte Adhesion Deficiency. ### Explanation **Correct Option: A. Leukocyte Adhesion Deficiency (LAD)** **Why it is correct:** Leukocyte Adhesion Deficiency (Type 1) is a primary immunodeficiency caused by a defect in the **CD18 subunit of $\beta_2$-integrins**. This defect prevents neutrophils from adhering to the vascular endothelium and migrating into tissues (diapedesis). * **Delayed separation of the umbilical cord:** This is the classic hallmark of LAD. Normally, neutrophils infiltrate the cord stump to facilitate its detachment; in LAD, the absence of neutrophils at the site leads to delayed separation (often >30 days). * **Leukocytosis:** Because neutrophils cannot leave the bloodstream to enter tissues, they accumulate in the blood, leading to persistent, marked neutrophilic leukocytosis. * **Recurrent Infections:** Patients suffer from skin and mucosal infections (e.g., omphalitis, periodontitis) characterized by a **lack of pus formation** despite high white cell counts. * **Association:** While not a primary feature, LAD has been documented in case reports involving children with Down syndrome. **Why other options are incorrect:** * **B. Neonatal Sepsis:** While sepsis causes leukocytosis and infections, it does not explain the specific anatomical delay in umbilical cord separation. * **C. Histiocytosis-X (Langerhans Cell Histiocytosis):** This typically presents with seborrheic-like skin rashes, lytic bone lesions, and hepatosplenomegaly, rather than a specific defect in cord separation or integrin function. **High-Yield Clinical Pearls for NEET-PG:** * **LAD Type 1:** Defect in **CD18** (Integrins). * **LAD Type 2:** Defect in **Sialyl-Lewis X** (Selectins); presents with short stature and intellectual disability. * **Key Triad:** Delayed cord separation + Recurrent "cold" infections (no pus) + Extreme neutrophilia. * **Diagnosis:** Confirmed by **Flow Cytometry** showing decreased expression of CD11/CD18.

Q: Which of the following is a feature of Henoch-Schönlein purpura?

Palpable purpura and arthralgia. **Explanation:** **Henoch-Schönlein Purpura (HSP)**, now commonly referred to as **IgA Vasculitis**, is the most common systemic vasculitis in children. It is a small-vessel vasculitis characterized by the deposition of IgA-dominant immune complexes. 1. **Why Option A is correct:** The classic clinical tetrad of HSP includes **palpable purpura** (without thrombocytopenia), **arthralgia/arthritis**, abdominal pain, and renal disease (hematuria). Palpable purpura is the hallmark finding, typically distributed over the buttocks and lower extremities. Arthralgia occurs in about 75% of cases, most commonly affecting the knees and ankles. Therefore, Option A represents the most comprehensive clinical feature among the choices. 2. **Why other options are incorrect:** * **Option B:** While palpable purpura is a feature, Option A is a more complete description of the systemic nature of the disease. * **Option C:** HSP is primarily a **pediatric disease**, with a peak incidence between ages 3 and 10 years. It is rare in infants and less common in adults. * **Option D:** A defining feature of HSP is that it is a **non-thrombocytopenic purpura**. The platelet count is characteristically normal or even elevated (thrombocytosis). This distinguishes it from Immune Thrombocytopenic Purpura (ITP). **Clinical Pearls for NEET-PG:** * **Preceding Event:** Often follows an Upper Respiratory Tract Infection (URTI), specifically Group A *Streptococcus*. * **Renal Involvement:** The most serious long-term complication is **HSP nephritis**, which is histologically identical to IgA Nephropathy (Berger’s disease). * **Gastrointestinal:** Intussusception (typically ileo-ileal) is a known surgical complication. * **Diagnosis:** Primarily clinical; skin biopsy shows **leukocytoclastic vasculitis** with IgA deposition on immunofluorescence.

Q: Which of the following is NOT a criterion for Juvenile Rheumatoid Arthritis?

Age greater than 16 years. **Explanation:** Juvenile Idiopathic Arthritis (JIA), formerly known as Juvenile Rheumatoid Arthritis (JRA), is defined by a specific set of clinical criteria designed to distinguish it from adult inflammatory arthritides. **Why Option A is the correct answer:** The fundamental definition of JIA requires the **onset of symptoms before the age of 16 years**. Therefore, "Age greater than 16 years" is an exclusion criterion and does not fit the diagnostic framework. If the disease starts after age 16, it is classified under adult rheumatoid arthritis or other adult-onset connective tissue disorders. **Analysis of other options:** * **Option B & C (Duration):** To diagnose JIA, arthritis must persist for a minimum of **6 weeks**. While Option B (3 weeks) is technically incorrect in duration, and Option C (6 months) is longer than required, in the context of NEET-PG questions regarding "NOT a criterion," the age limit (Option A) is the absolute defining boundary. *Note: Standard criteria require ≥6 weeks; Option B is often used as a distractor in older question formats.* * **Option D (Joint Involvement):** JIA is characterized by the presence of objective arthritis (swelling or limitation of motion with pain) in **one or more joints**. This is a core requirement for the diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Subtypes:** The most common subtype is **Oligoarthritis** (involving ≤4 joints), which carries a high risk of **asymptomatic chronic anterior uveitis** (requires regular slit-lamp exams). * **Systemic JIA (Still’s Disease):** Characterized by daily "quotidian" fevers, evanescent salmon-pink rashes, and hepatosplenomegaly. * **Markers:** Rheumatoid Factor (RF) is usually negative in children (only positive in ~10-15% of cases, typically older girls). ANA positivity is a strong risk factor for uveitis.

Q: A child presents with a constellation of findings including fever, disabling arthritis, rash, and blindness. What is the MOST likely diagnosis?

Juvenile rheumatoid arthritis. **Explanation:** The correct answer is **Juvenile Rheumatoid Arthritis (JRA)**, now more commonly referred to as **Juvenile Idiopathic Arthritis (JIA)**. The clinical triad of **fever, arthritis, and rash** is characteristic of Systemic-onset JIA (Still’s Disease). However, the inclusion of **blindness** is the diagnostic "clue" pointing toward JIA. Chronic non-granulomatous **anterior uveitis (iridocyclitis)** is a classic extra-articular manifestation of JIA, particularly the oligoarticular subtype. If left untreated, it leads to cataracts, glaucoma, and permanent blindness. Since uveitis is often asymptomatic in children, regular slit-lamp examinations are mandatory. **Why the other options are incorrect:** * **Rheumatic Fever:** While it presents with fever and migratory polyarthritis, it typically involves the heart (carditis) and skin (erythema marginatum). It does **not** cause uveitis or blindness. * **Lyme Disease:** Can cause fever, rash (erythema chronicum migrans), and arthritis, but the arthritis is usually episodic and involves large joints (like the knee). Blindness is not a standard feature. * **Henoch-Schönlein Purpura (HSP):** This is a small-vessel vasculitis characterized by a palpable purpuric rash (usually on the lower limbs), abdominal pain, and arthritis. It involves the kidneys but does not cause blindness. **NEET-PG High-Yield Pearls:** * **Uveitis Risk:** Highest in girls with **Oligoarticular JIA** who are **ANA positive**. * **Still’s Rash:** Characteristically salmon-pink, evanescent (comes and goes with fever), and non-pruritic. * **Macrophage Activation Syndrome (MAS):** A life-threatening complication specifically associated with Systemic JIA. * **First-line Treatment:** NSAIDs are used initially; Methotrexate is the most common DMARD used for persistent disease.

Q: Which vasculitis is seen most commonly in childhood?

Henoch-Schonlein purpura. **Explanation:** **Henoch-Schönlein Purpura (HSP)**, now commonly referred to as **IgA Vasculitis**, is the most common vasculitis seen in the pediatric population. It is a small-vessel vasculitis characterized by the deposition of IgA-dominant immune complexes. It typically follows an upper respiratory tract infection and presents with a classic tetrad: non-thrombocytopenic palpable purpura (usually on lower limbs), arthralgia/arthritis, abdominal pain, and renal involvement (hematuria). **Analysis of Options:** * **Kawasaki Disease (Option A):** This is the second most common vasculitis in children. It is a medium-vessel vasculitis and the leading cause of acquired heart disease in children in developed countries. While common, its incidence is lower than that of HSP. * **Susac Syndrome (Option B):** This is an extremely rare microangiopathy characterized by a clinical triad of encephalopathy, branch retinal artery occlusions, and sensorineural hearing loss. It is not a common pediatric condition. * **Giant Cell Arteritis (Option D):** This is a large-vessel vasculitis that almost exclusively affects adults over the age of 50. It is virtually never seen in childhood. **NEET-PG High-Yield Pearls:** * **HSP Diagnosis:** Primarily clinical; platelet count will be normal (distinguishes it from ITP). * **HSP Complication:** Intussusception (usually ileo-ileal) is the most common GI complication. * **Prognosis:** Generally excellent, but long-term prognosis depends on the severity of **renal involvement**. * **Biopsy:** If performed (skin or kidney), it shows **leukocytoclastic vasculitis** with IgA deposits on immunofluorescence.

Q: Wiskott Aldrich syndrome commonly consists of which of the following findings, except?

Urethritis. **Explanation:** Wiskott-Aldrich Syndrome (WAS) is an **X-linked recessive** primary immunodeficiency caused by a mutation in the **WAS gene**, which encodes the WAS protein (WASp). This protein is crucial for actin cytoskeleton remodeling in hematopoietic cells. **Why Urethritis is the Correct Answer:** Urethritis is not a component of the classic WAS triad. The syndrome primarily affects the immune system and platelets. While patients are prone to infections, these typically manifest as respiratory tract infections, skin infections, or meningitis rather than isolated urethritis. **Analysis of Incorrect Options:** * **Bleeding (Thrombocytopenia):** This is often the earliest manifestation. It is characterized by **microthrombocytopenia** (small-sized platelets) and a low platelet count, leading to petechiae, purpura, and mucosal bleeding. * **Eczema:** A hallmark feature that typically appears in infancy, resembling atopic dermatitis but often more severe and persistent. * **Recurrent Bacterial Infections:** Due to combined B-cell and T-cell dysfunction, patients suffer from recurrent infections, particularly with encapsulated organisms like *S. pneumoniae* and *H. influenzae*. **High-Yield Clinical Pearls for NEET-PG:** * **The Classic Triad:** Remember the mnemonic **TIE**—**T**hrombocytopenia, **I**mmunodeficiency (recurrent infections), and **E**czema. * **Laboratory Findings:** Low IgM, normal/high IgG, and **elevated IgA and IgE**. * **Platelet Morphology:** Small platelets (low Mean Platelet Volume) are pathognomonic for WAS. * **Complications:** Increased risk of autoimmune diseases and **B-cell lymphomas**. * **Treatment:** Hematopoietic stem cell transplant (HSCT) is the definitive cure.

Q: Which of the following is diagnostic for juvenile idiopathic arthritis (JIA)?

Clinical diagnosis without any diagnostic laboratory tests. **Explanation:** Juvenile Idiopathic Arthritis (JIA) is primarily a **clinical diagnosis of exclusion**. According to the ILAR (International League of Associations for Rheumatology) criteria, JIA is defined as arthritis of unknown etiology persisting for at least **6 weeks** in a child aged **less than 16 years**, after other causes (like infection or malignancy) have been ruled out. There is no single pathognomonic laboratory test or imaging modality that confirms JIA. **Analysis of Options:** * **Option D (Correct):** Diagnosis relies on history and physical examination (identifying joint swelling, pain, or limited range of motion). Lab tests are used for subtyping and prognosis, not for the primary diagnosis. * **Option A (ANA):** ANA is not diagnostic. While it is often positive in oligoarticular JIA, its primary clinical utility is as a **prognostic marker** for an increased risk of **chronic anterior uveitis**, necessitating frequent slit-lamp exams. * **Option B (ESR):** ESR and CRP are non-specific markers of inflammation. They may be elevated (especially in Systemic JIA), but a normal ESR does not rule out JIA. * **Option C (Rheumatoid Factor):** RF is negative in the vast majority of JIA patients. It is only used to classify the "Polyarticular RF-positive" subtype, which represents less than 5-10% of cases. **High-Yield Clinical Pearls for NEET-PG:** * **Systemic JIA (Still’s Disease):** Characterized by daily "quotidian" fevers and an evanescent salmon-pink rash. * **Most common subtype:** Oligoarticular JIA (affects $\le$ 4 joints). * **Uveitis:** Most common in ANA-positive, oligoarticular girls; often asymptomatic, requiring screening. * **First-line treatment:** NSAIDs; Methotrexate is the most common DMARD used.

Question 1

What is a characteristic feature of Systemic Juvenile Idiopathic Arthritis?

Accepted Answer

RA factor is negative

Answer

Uveitis is a feature

Answer

It occurs after 16 years of age

Answer

NSAIDs are contraindicated

Question 2

A child presents with delayed separation of the umbilical cord, leukocytosis, Down syndrome, and recurrent infections. What is the most likely diagnosis?

Accepted Answer

Leukocyte Adhesion Deficiency

Answer

Neonatal Sepsis

Answer

Histiocytosis-X

Answer

All of the above

Question 3

Which of the following is a feature of Henoch-Schönlein purpura?

Accepted Answer

Palpable purpura and arthralgia

Answer

Palpable purpura

Answer

Occurs only in elderly persons

Answer

Thrombocytopenia

Question 4

Which of the following is NOT a criterion for Juvenile Rheumatoid Arthritis?

Accepted Answer

Age greater than 16 years

Answer

Arthritis duration greater than 3 weeks

Answer

Arthritis duration greater than 6 months

Answer

One or more joint involvement

Question 5

A child presents with a constellation of findings including fever, disabling arthritis, rash, and blindness. What is the MOST likely diagnosis?

Accepted Answer

Juvenile rheumatoid arthritis

Answer

Rheumatic fever

Answer

Lyme disease

Answer

Henoch-Schoenlein vasculitis

Question 6

Which of the following statements regarding Systemic Lupus Erythematosus (SLE) in children is true?

Accepted Answer

None of the above statements are true.

Answer

Skin pigmentation is more common than in adults.

Answer

There is no sex difference in prevalence.

Answer

Renal involvement is more common.

Question 7

Which vasculitis is seen most commonly in childhood?

Accepted Answer

Henoch-Schonlein purpura

Answer

Kawasaki disease

Answer

Susac syndrome

Answer

Giant cell arteritis

Question 8

Wiskott Aldrich syndrome commonly consists of which of the following findings, except?

Accepted Answer

Urethritis

Answer

Recurrent bacterial infections

Answer

Eczema

Answer

Bleeding

Question 9

An eight-year-old child presents with recurrent chest infections since early childhood. Serological examination reveals a deficiency in a certain immunoglobulin. Which of the following is the most common immunoglobulin deficiency observed in such cases?

Accepted Answer

IgA

Answer

IgE

Answer

IgG

Answer

IgD

Question 10

Which of the following is diagnostic for juvenile idiopathic arthritis (JIA)?

Accepted Answer

Clinical diagnosis without any diagnostic laboratory tests

Answer

Anti-nuclear antibody

Answer

ESR

Answer

Rheumatoid factor

Immunology and Allergies — MCQs

Immunology and Allergies — MCQs

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