Rheumatology and Immunology Practice Questions

Q: What is the most common cardiac involvement in rheumatoid arthritis?

Pericarditis. **Explanation:** **1. Why Pericarditis is the Correct Answer:** Pericarditis is the most common clinical and pathological cardiac manifestation of Rheumatoid Arthritis (RA). While it is often asymptomatic in up to 50% of patients (detected primarily via autopsy or echocardiography), symptomatic pericarditis occurs in about 10% of cases. It typically presents in patients with long-standing, seropositive (RF+) disease and extra-articular manifestations. The pericardial fluid in RA is characteristically "exudative," showing low glucose levels, low complement levels, and high LDH. **2. Analysis of Incorrect Options:** * **Pancarditis (A):** This involves inflammation of all three layers of the heart (pericardium, myocardium, and endocardium). While RA can affect multiple layers, it rarely presents as a simultaneous pancarditis; this is more characteristic of Acute Rheumatic Fever. * **Myocarditis (C):** Myocardial involvement in RA is rare and usually manifests as granulomatous nodules or interstitial myocarditis. It is significantly less common than pericardial disease. * **Endocarditis (D):** While RA can cause valvular nodules (Libman-Sacks endocarditis is specific to SLE, not RA), clinical endocarditis or valvular dysfunction is much rarer than pericarditis. **3. NEET-PG High-Yield Pearls:** * **Most Common Cardiac Manifestation:** Pericarditis. * **Most Common Cause of Death in RA:** Ischemic Heart Disease (due to accelerated atherosclerosis caused by chronic inflammation). * **Specific Finding:** Rheumatoid nodules can occasionally form on the conduction system, leading to heart blocks [1]. * **Pericardial Fluid Profile:** Low Glucose (<30 mg/dL) is a classic board-exam pointer for Rheumatoid pericarditis/pleuritis.

Q: Which antibody is associated with a reduced risk of lupus nephritis in Systemic Lupus Erythematosus (SLE)?

Anti-La antibody. **Explanation:** The correct answer is **Anti-La antibody (SS-B)**. In Systemic Lupus Erythematosus (SLE), certain autoantibodies serve as markers for specific organ involvement or protection. Clinical studies have consistently shown that the presence of **Anti-Ro (SS-A) and Anti-La (SS-B)** antibodies is associated with a **decreased risk of developing lupus nephritis** [1]. While these antibodies are classically linked to Sjögren’s syndrome and neonatal lupus (congenital heart block), in the context of SLE, they appear to be "protective" against severe renal disease compared to patients who are positive for anti-dsDNA [1]. **Analysis of Incorrect Options:** * **Anti-ribosomal P antibody:** This is highly specific for SLE and is strongly associated with **neuropsychiatric lupus** (lupus psychosis) and sometimes hepatitis, rather than renal protection. * **Anti-histone antibody:** This is the hallmark of **Drug-Induced Lupus (DIL)**. While DIL typically spares the kidneys and CNS, the antibody itself is not considered a "protective factor" for nephritis in idiopathic SLE. * **Antinuclear antibody (ANA):** This is the best initial screening test (high sensitivity) but has no prognostic value regarding specific organ involvement like nephritis due to its lack of specificity [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Most Specific for SLE:** Anti-dsDNA and Anti-Smith (Anti-Sm) [1]. * **Best Marker for Disease Activity/Nephritis:** Anti-dsDNA (levels correlate with renal flares and low C3/C4) [1]. * **Neonatal Lupus:** Associated with Anti-Ro and Anti-La; most common permanent complication is **congenital complete heart block** [1]. * **Subacute Cutaneous Lupus (SCLE):** Strongly associated with Anti-Ro antibodies [1].

Q: Which of the following conditions is associated with ANCA?

All of the above. **Explanation:** Anti-Neutrophil Cytoplasmic Antibodies (ANCA) are autoantibodies directed against antigens found in the cytoplasmic granules of neutrophils and monocytes. While classically associated with small-vessel vasculitides, they can also be found in various systemic autoimmune conditions. * **Wegener’s Granulomatosis (Granulomatosis with Polyangiitis - GPA):** This is the classic association. Approximately 90% of patients with active, generalized GPA are positive for **c-ANCA (PR3-ANCA)**. * **Churg-Strauss Disease (Eosinophilic Granulomatosis with Polyangiitis - EGPA):** About 40-60% of patients with EGPA are ANCA-positive, typically showing a **p-ANCA (MPO-ANCA)** pattern [1]. * **SLE (Systemic Lupus Erythematosus):** While not a primary diagnostic marker, ANCA (specifically **p-ANCA/atypical ANCA**) can be found in 15-20% of SLE patients. Its presence in SLE is often associated with specific manifestations like lupus nephritis or vasculitis. Since all three conditions listed can demonstrate ANCA positivity, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **c-ANCA (Cytoplasmic):** Target antigen is **Proteinase-3 (PR3)**. Most specific for Wegener’s Granulomatosis. 2. **p-ANCA (Perinuclear):** Target antigen is **Myeloperoxidase (MPO)**. Associated with Microscopic Polyangiitis (MPA), EGPA, and Primary Sclerosing Cholangitis (PSC) [1]. 3. **Atypical ANCA:** Often seen in Inflammatory Bowel Disease (especially Ulcerative Colitis) and Drug-induced Lupus (e.g., Hydralazine, Propylthiouracil). 4. **Pauci-immune Glomerulonephritis:** A hallmark of ANCA-associated vasculitides, characterized by minimal immune complex deposition on immunofluorescence.

Q: What condition is characterized by the pathognomic lesion known as a tophus?

Gout. **Explanation:** **Gout** is the correct answer because a **tophus** (plural: tophi) is the pathognomonic clinical feature of chronic tophaceous gout [1]. It represents a localized deposit of **monosodium urate (MSU) crystals** in soft tissues, joints, or cartilage [2]. These lesions typically appear as firm, painless, yellowish-white nodules [1]. Under polarized light microscopy, these crystals exhibit **strong negative birefringence** and a needle-shaped morphology. Common sites include the olecranon bursa, Achilles tendon, and the helix of the ear [1]. **Analysis of Incorrect Options:** * **Multiple Myeloma:** Characterized by plasma cell dyscrasia, "punched-out" lytic bone lesions, and Bence-Jones proteinuria, but does not involve urate tophi. * **Cystinosis:** A lysosomal storage disorder leading to the accumulation of cystine crystals in various organs (kidneys, eyes). While it involves crystal deposition, these are not tophi. * **Bale’s Disease:** This is not a standard clinical entity associated with crystal arthropathies or tophaceous lesions. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Identification of MSU crystals in synovial fluid or tophus aspirate. * **Radiology:** Tophi appear as "punched-out" erosions with **overhanging edges** (Martel’s sign) on X-ray. * **Dual-Energy CT (DECT):** The most sensitive imaging modality for detecting and quantifying the total urate burden. * **Management:** Acute attacks are treated with NSAIDs, Colchicine, or Steroids; chronic management requires Urate Lowering Therapy (ULT) like Allopurinol or Febuxostat [3].

Q: Rashes seen over the cheeks and nose are the characteristic feature of which condition?

Systemic Lupus Erythematosus (SLE). The characteristic rash described over the cheeks and nose is the **Malar rash** (also known as the **Butterfly rash**). **1. Why Systemic Lupus Erythematosus (SLE) is correct:** The malar rash is a classic cutaneous manifestation of SLE [1]. It is a fixed, flat, or raised erythematous rash over the malar eminences (cheeks) that typically **spares the nasolabial folds** [1]. This sparing is a crucial diagnostic differentiator from other facial rashes like seborrheic dermatitis. The rash is often photosensitive and may precede or coincide with systemic flares. **2. Why the other options are incorrect:** * **Scleroderma:** Characterized by skin thickening and tightening (sclerodactyly). Facial features include a "mask-like" facies, microstomia (small mouth), and beak-like nose, but not a malar rash. * **Acrodermatitis enteropathica:** A rare genetic disorder of **zinc deficiency**. It presents with periorificial (around the mouth, anus) and acral (limbs) dermatitis, alopecia, and diarrhea, rather than a butterfly distribution. * **Pemphigus:** An autoimmune blistering disease. While Pemphigus erythematosus (Senear-Usher syndrome) can show a malar distribution, the primary lesions are vesicles and bullae that rupture to form crusts, unlike the fixed erythema of SLE. **Clinical Pearls for NEET-PG:** * **Butterfly Rash Sparing Nasolabial Folds:** Pathognomonic for SLE [1]. * **Drug-Induced Lupus:** Usually presents with skin and joint symptoms but rarely involves the kidneys or CNS. Common triggers: **H**ydralazine, **I**soniazid, **P**rocainamide (**HIP**). * **Antibodies:** **Anti-dsDNA** is highly specific for SLE and correlates with disease activity (especially lupus nephritis), while **Anti-Smith** is the most specific antibody overall. * **Histology:** SLE skin lesions show liquefactive degeneration of the basal layer and IgG/complement deposits at the dermo-epidermal junction (**Lupus Band Test**).

Q: What is the treatment of choice in seronegative spondyloarthritis?

Indomethacin. **Explanation:** **1. Why Indomethacin is the Correct Answer:** Seronegative spondyloarthritides (SpA), such as Ankylosing Spondylitis (AS), Reactive Arthritis, and Psoriatic Arthritis, are characterized by axial involvement and enthesitis [2]. **Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)** are the first-line treatment of choice for managing pain and stiffness. Among NSAIDs, **Indomethacin** is traditionally considered the gold standard and the most effective agent for symptomatic relief in SpA. It works by inhibiting prostaglandin synthesis, effectively reducing the spinal inflammation and peripheral arthritis associated with these conditions [1]. **2. Analysis of Incorrect Options:** * **A. Phenylbutazone:** While highly effective for AS, it is no longer the treatment of choice due to severe potential side effects, including **aplastic anemia** and agranulocytosis. It is reserved only for refractory cases. * **B. Aspirin:** Aspirin is generally ineffective at standard doses for the intense axial inflammation seen in SpA and requires very high, often toxic, doses to achieve an anti-inflammatory effect. * **D. Corticosteroids:** Systemic steroids have **minimal to no role** in treating the axial disease of seronegative SpA. While local injections may help peripheral enthesitis, long-term systemic use is avoided due to lack of efficacy and significant side effects. **3. NEET-PG High-Yield Pearls:** * **First-line:** NSAIDs (Indomethacin/Naproxen) [1]. * **Disease-Modifying (Peripheral):** Sulfasalazine is used for peripheral joint involvement but is **ineffective for axial (spinal) disease**. * **Biologicals:** TNF-alpha inhibitors (e.g., Etanercept, Infliximab) are the treatment of choice if NSAIDs fail [3]. * **Key Association:** HLA-B27 is strongly associated with these conditions (highest in Ankylosing Spondylitis, ~90%) [2].

Q: Which of the following is TRUE about rheumatoid factor?

19S globulin. Rheumatoid Factor (RF) is an autoantibody directed against the **Fc portion of the IgG molecule**. In most clinical assays, the RF measured belongs to the **IgM class**. **1. Why Option D is Correct:** Immunoglobulins are categorized by their sedimentation coefficient (measured in Svedberg units, S). * **IgM** is a large pentameric molecule with a high molecular weight (approx. 900,000 Daltons), giving it a sedimentation coefficient of **19S**. * Since the standard RF detected in laboratories is an IgM antibody, it is characterized as a **19S globulin**. **2. Why Other Options are Incorrect:** * **Option A (Albumin):** Albumin is a transport protein produced by the liver, not an antibody. RF is an immunoglobulin (globulin). * **Option C (7S globulin):** This refers to monomeric antibodies like **IgG**. While RF can occasionally be of the IgG or IgA class, these are not the standard "Rheumatoid Factors" measured in routine clinical practice. * **Option B (17S globulin):** This is not a standard sedimentation value for major human immunoglobulins. **High-Yield Clinical Pearls for NEET-PG:** * **Sensitivity vs. Specificity:** RF is present in about 70–80% of patients with Rheumatoid Arthritis (RA). However, it is **not specific** for RA [1]. * **Other Conditions with (+) RF:** It can be found in Sjogren’s syndrome (highest titers), SLE, Chronic Hepatitis, Infective Endocarditis, and even in 5% of the healthy elderly population [2]. * **Prognostic Value:** High titers of RF in RA patients correlate with more severe erosive disease and extra-articular manifestations (e.g., rheumatoid nodules, vasculitis). * **Rose-Waaler Test:** An older hemagglutination test for RF using sheep RBCs coated with rabbit IgG.

Q: Macrophage activation syndrome is most commonly seen in association with which of the following conditions?

Juvenile Rheumatoid Arthritis. **Explanation:** **Macrophage Activation Syndrome (MAS)** is a life-threatening complication characterized by an overwhelming inflammatory response due to the uncontrolled proliferation of T-lymphocytes and well-differentiated macrophages. These macrophages exhibit **hemophagocytosis** (engulfing erythrocytes, leukocytes, and platelets) in the bone marrow and reticuloendothelial organs. 1. **Why Juvenile Rheumatoid Arthritis (JRA) is correct:** MAS is most classically and frequently associated with **Systemic Juvenile Idiopathic Arthritis (sJIA)**, formerly known as Still’s disease or JRA [1]. It occurs in approximately 10% of sJIA patients and is considered a form of secondary Hemophagocytic Lymphohistiocytosis (HLH). The underlying trigger is often an infection or a change in medication, leading to a "cytokine storm" (specifically IL-1, IL-6, and TNF-alpha). 2. **Why other options are incorrect:** * **SLE (Systemic Lupus Erythematosus):** While MAS can occur in SLE, it is significantly less common than in sJIA. * **Systemic Sclerosis & Sweet’s Syndrome:** These conditions are not typically associated with the systemic hyperinflammation or the specific cytokine profile required to trigger MAS. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Triad:** High-grade non-remitting fever, hepatosplenomegaly, and lymphadenopathy. * **Laboratory Hallmarks:** The "Paradox of MAS"—while the patient is highly inflamed, the **ESR characteristically drops** (due to fibrinogen consumption). * **Key Markers:** High Ferritin (often >10,000 ng/mL), high Triglycerides, low Fibrinogen, and cytopenias (anemia, thrombocytopenia). * **Treatment:** High-dose corticosteroids are first-line; Cyclosporine or IL-1 inhibitors (Anakinra) are used in refractory cases.

Q: What is the loading dose of leflunomide in rheumatoid arthritis?

100 mg. **Explanation:** Leflunomide is a Disease-Modifying Antirheumatic Drug (DMARD) that acts by inhibiting the mitochondrial enzyme **dihydroorotate dehydrogenase (DHODH)**, thereby blocking *de novo* pyrimidine synthesis. This inhibits the proliferation of activated T-cells. **Why 100 mg is correct:** Leflunomide has a very long half-life (approximately 14–15 days) due to extensive enterohepatic circulation. To achieve therapeutic steady-state plasma concentrations rapidly, a **loading dose of 100 mg once daily for 3 consecutive days** is recommended. Following this, a maintenance dose is initiated. **Analysis of Incorrect Options:** * **A (20 mg):** This is the standard **daily maintenance dose** for most patients with active rheumatoid arthritis. * **B (10 mg):** This is the lower-end maintenance dose, often used for patients who cannot tolerate 20 mg due to side effects like diarrhea or hepatotoxicity. * **D (400 mg):** This is an inappropriately high dose and is not used in clinical practice; it would significantly increase the risk of severe toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Active Metabolite:** Leflunomide is a prodrug; its active metabolite is **Teriflunomide (A77 1726)**. * **Washout Procedure:** Due to its long half-life, if a patient needs to stop the drug (e.g., for pregnancy or toxicity), **Cholestyramine** is used to enhance fecal excretion. * **Teratogenicity:** It is strictly contraindicated in pregnancy (Category X). * **Monitoring:** Baseline and periodic monitoring of **Liver Function Tests (LFTs)** and CBC is mandatory due to risks of hepatotoxicity and myelosuppression. * **Trend Note:** In modern practice, the loading dose is often omitted to reduce the incidence of gastrointestinal side effects (diarrhea), but for examination purposes, 100 mg remains the standard answer.

Question 1

What is the most common cardiac involvement in rheumatoid arthritis?

Accepted Answer

Pericarditis

Answer

Pancarditis

Answer

Myocarditis

Answer

Endocarditis

Question 2

Which antibody is associated with a reduced risk of lupus nephritis in Systemic Lupus Erythematosus (SLE)?

Accepted Answer

Anti-La antibody

Answer

Anti-ribosomal P antibody

Answer

Anti-histone antibody

Answer

Antinuclear antibody (ANA)

Question 3

Which of the following conditions is associated with ANCA?

Accepted Answer

All of the above

Answer

Wegener's granulomatosis

Answer

Churg-Strauss' disease

Answer

SLE

Question 4

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

Accepted Answer

Gout

Answer

Multiple myeloma

Answer

Cystinosis

Answer

Bale's disease

Question 5

A 17-year-old woman presents with agitation and a history of malaise, joint pain, weight loss, and sporadic fever over the past 3 months. Physical examination reveals a temperature of 38°C (101°F), malar rash, erythematous-pink plaques with telangiectatic vessels, oral ulcers, and non-blanching purpuric papules on her legs. Laboratory studies show elevated BUN and creatinine levels, and a positive anti-double-stranded DNA antibody test. Biopsy of sun-damaged lesional skin would most likely show which of the following histopathologic findings?

Accepted Answer

Granular distribution of immune complexes in the basement membrane zone

Answer

Acanthosis, parakeratosis, and neutrophils within the stratum corneum

Answer

Early dermal-epidermal separation mediated by eosinophils

Answer

Linear IgA deposits within dermal papillae

Question 6

Rashes seen over the cheeks and nose are the characteristic feature of which condition?

Accepted Answer

Systemic Lupus Erythematosus (SLE)

Answer

Scleroderma

Answer

Acrodermatitis enteropathica

Answer

Pemphigus

Question 7

What is the treatment of choice in seronegative spondyloarthritis?

Accepted Answer

Indomethacin

Answer

Phenylbutazone

Answer

Aspirin

Answer

Corticosteroid

Question 8

Which of the following is TRUE about rheumatoid factor?

Accepted Answer

19S globulin

Answer

An albumin

Answer

17S globulin

Answer

7S globulin

Question 9

Macrophage activation syndrome is most commonly seen in association with which of the following conditions?

Accepted Answer

Juvenile Rheumatoid Arthritis

Answer

Systemic sclerosis

Answer

Sweet's syndrome

Answer

SLE

Question 10

What is the loading dose of leflunomide in rheumatoid arthritis?

Accepted Answer

100 mg

Answer

20 mg

Answer

10 mg

Answer

400 mg

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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