Rheumatology and Immunology Practice Questions

Q: Moderate to high titres of anti-DNA and anti-Smith antibodies are almost pathognomonic of which condition?

Systemic Lupus Erythematosus (SLE). ### Explanation **Correct Answer: A. Systemic Lupus Erythematosus (SLE)** **Medical Concept:** Systemic Lupus Erythematosus (SLE) is a multisystem autoimmune disease characterized by the production of various autoantibodies. While **Anti-nuclear antibody (ANA)** is the most sensitive screening test (positive in >95% of cases), it lacks specificity. In contrast, **Anti-dsDNA** and **Anti-Smith (Anti-Sm)** antibodies are highly specific for SLE. * **Anti-dsDNA:** Its levels often correlate with disease activity, particularly lupus nephritis. * **Anti-Smith:** It is directed against small nuclear ribonucleoproteins (snRNPs). While only present in about 10–30% of patients, it is considered **pathognomonic** because it is rarely found in any other condition. **Why other options are incorrect:** * **B. Erythema Multiforme (EM):** This is a hypersensitivity reaction, most commonly triggered by infections (like Herpes Simplex Virus) or drugs. It is not characterized by specific autoantibodies like Anti-Sm. * **C. Lichen Planus:** This is a T-cell mediated chronic inflammatory condition affecting the skin and mucosa. Diagnosis is clinical and histological (Civatte bodies, Saw-tooth rete ridges), not serological. * **D. All of the above:** Incorrect, as the mentioned antibodies are specific to the pathogenesis of SLE only. **High-Yield Clinical Pearls for NEET-PG:** * **Most Sensitive Test for SLE:** ANA (Best initial screening). * **Most Specific Tests for SLE:** Anti-dsDNA and Anti-Smith. * **Drug-Induced Lupus:** Characterized by **Anti-Histone antibodies**; Anti-dsDNA is usually negative. * **Neonatal Lupus/Congenital Heart Block:** Strongly associated with **Anti-Ro (SS-A)** and **Anti-La (SS-B)** antibodies. * **Mixed Connective Tissue Disease (MCTD):** Associated with high titers of **Anti-U1 RNP**.

Q: Which one of the following is not included in Jones's Major criteria?

High ESR. The **Jones Criteria** are used to diagnose the first episode of **Acute Rheumatic Fever (ARF)**, a non-suppurative sequela of Group A Streptococcal pharyngeal infection [1]. The criteria are divided into **Major** and **Minor** categories. ### Why High ESR is the Correct Answer **High ESR (Erythrocyte Sedimentation Rate)** is a **Minor criterion**, not a Major one. Minor criteria represent non-specific systemic signs of inflammation and include: * **Clinical:** Fever, Polyarthralgia. * **Laboratory:** Elevated acute phase reactants (ESR ≥ 60 mm/h or CRP ≥ 3.0 mg/dL), Prolonged PR interval on ECG. ### Why the Other Options are Incorrect Options A, B, and C are all **Major criteria** (Mnemonic: **J♥NES**): * **Pancarditis (J - Joint/Carditis):** Clinical or subclinical evidence of carditis (valvulitis, myocarditis, or pericarditis) [1]. * **Chorea (N - Nodes/Chorea):** Specifically **Sydenham’s chorea** (St. Vitus Dance), characterized by rapid, purposeless movements. * **Subcutaneous Nodules (S - Subcutaneous):** Small, painless, firm nodules usually found over bony prominences or tendons. * *Note: The other major criteria are **Polyarthritis** and **Erythema Marginatum**.* ### NEET-PG High-Yield Pearls 1. **Diagnosis Requirement:** 2 Major OR 1 Major + 2 Minor criteria, PLUS evidence of preceding Strep infection [1]. 2. **Exception:** Chorea or indolent carditis can be diagnostic of ARF on their own without evidence of preceding infection [1]. 3. **Joint Involvement:** In low-risk populations, only **Polyarthritis** is major; however, in high-risk populations (like India), **Monoarthritis** or **Polyarthralgia** can be considered Major criteria under the revised Jones criteria. 4. **Most Common Manifestation:** Migratory Polyarthritis. 5. **Most Serious Manifestation:** Carditis (leads to chronic rheumatic heart disease) [2].

Q: Which is the most common site of subcutaneous nodules in rheumatoid arthritis?

Elbow. **Explanation:** Rheumatoid nodules are the most common extra-articular manifestation of Rheumatoid Arthritis (RA), occurring in approximately 20–30% of patients, typically those who are Rheumatoid Factor (RF) positive [1]. **1. Why the Elbow is Correct:** Subcutaneous nodules in RA have a predilection for **pressure points** and **extensor surfaces**. The **olecranon process (elbow)** is the most common site because it is frequently subjected to mechanical stress and repetitive minor trauma [1]. Histologically, these nodules consist of a central area of fibrinoid necrosis surrounded by palisading macrophages and a peripheral layer of connective tissue. **2. Analysis of Incorrect Options:** * **Wrist:** While RA frequently involves the wrist joints (synovitis), subcutaneous nodules are less common here compared to the olecranon. * **Achilles Tendon:** This is a classic site for **Xanthomas** (in hyperlipidemia) or nodules in Gout (tophi), but it is not the primary site for RA nodules. * **Occiput:** This is a common site for pressure sores in bedbound patients or nodules in Rheumatic Fever (though rare), but it is not the most frequent site in RA. **3. Clinical Pearls for NEET-PG:** * **Serology:** Rheumatoid nodules are strongly associated with **RF positivity** and **anti-CCP antibodies**. Their presence often indicates more severe systemic disease. * **Methotrexate-induced accelerated nodulosis:** Occasionally, patients on Methotrexate therapy may experience a paradoxical increase in small nodules, typically on the fingers. * **Differential Diagnosis:** Always differentiate RA nodules from **Gouty Tophi** (which may ulcerate and discharge chalky material) and **Basal Cell Carcinoma** (if located on the face). * **Internal Sites:** Though rare, nodules can occur in the lungs (Caplan syndrome), heart valves, or sclera (scleromalacia perforans) [1].

Q: Reiter's syndrome is associated with which of the following causative agents?

Chlamydia. **Explanation:** **Reiter’s Syndrome**, now more commonly referred to as **Reactive Arthritis (ReA)**, is an asymmetric inflammatory polyarthritis that develops following an extra-articular infection, typically of the gastrointestinal (GI) or urogenital (UG) tract [1]. 1. **Why Chlamydia is Correct:** * *Chlamydia trachomatis* is the most common cause of **urogenital** reactive arthritis worldwide [1]. It is an obligate intracellular pathogen. The immune system triggers a cross-reactive response (molecular mimicry) against the joints following the primary infection. * Classic Reiter’s Syndrome is defined by the clinical triad: **Urethritis, Conjunctivitis, and Arthritis** ("Can't see, can't pee, can't climb a tree") [1]. 2. **Why the other options are incorrect:** * **Neisseria:** While *N. gonorrhoeae* causes "Gonococcal Arthritis," this is a **septic arthritis** (direct joint infection) rather than a reactive one. Reactive arthritis is, by definition, sterile. * **Mycoplasma:** Although *Mycoplasma genitalium* can cause urethritis, it is a rare and inconsistent trigger for the full Reiter’s triad compared to Chlamydia. * **Herpes virus:** Viral infections (like B19 or Rubella) cause viral arthritis, but they are not associated with the specific pathophysiology or triad of Reiter’s Syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Genetic Association:** Strongly associated with **HLA-B27** (positive in ~80% of cases) [1]. * **Other Triggers (Enteric):** *Shigella flexneri*, *Salmonella*, *Campylobacter*, and *Yersinia* [1]. * **Cutaneous Manifestations:** Look for **Keratoderma blennorrhagicum** (vesicular palm/sole rash) and **Circinate balanitis** [1]. * **Treatment:** NSAIDs are first-line; antibiotics treat the underlying infection but do not always resolve the arthritis.

Q: A lady presents with right knee swelling. Aspiration revealed the presence of calcium pyrophosphate dihydrate (CPPD) crystals. What is the next best investigation?

Thyroid-stimulating hormone (TSH). **Explanation:** The presence of **calcium pyrophosphate dihydrate (CPPD)** crystals in joint aspirate confirms the diagnosis of **Pseudogout**. Unlike primary gout, pseudogout is frequently associated with underlying metabolic and endocrine disorders [1]. **Why TSH is the correct investigation:** Hypothyroidism is a well-established metabolic trigger for CPPD deposition. When a patient presents with pseudogout, it is mandatory to screen for reversible or manageable metabolic associations. The "Big Four" associations to screen for in CPPD are: 1. **Hypothyroidism** (hence, TSH is the next best step). 2. **Hyperparathyroidism** (check Calcium/PTH). 3. **Hemochromatosis** (check Ferritin/Iron studies) [3]. 4. **Hypomagnesemia.** **Analysis of Incorrect Options:** * **A & B (ANA and RF):** These are markers for systemic autoimmune diseases like SLE and Rheumatoid Arthritis. While these can coexist with joint swelling, they do not have a direct causal link with the formation of CPPD crystals. * **C (CPK):** This is a marker for muscle injury or inflammatory myositis (e.g., Dermatomyositis) [2]. It has no diagnostic value in crystal-induced arthropathies. **Clinical Pearls for NEET-PG:** * **Radiology:** Look for **Chondrocalcinosis** (linear calcification of articular cartilage), most commonly seen in the knee (meniscus) and wrist (triangular fibrocartilage). * **Microscopy:** CPPD crystals are **rhomboid-shaped** and show **weak positive birefringence** under polarized light (unlike the needle-shaped, strongly negative birefringent crystals of gout). * **Commonest Site:** The **Knee** is the most common joint involved in pseudogout (Gout favors the 1st MTP joint) [1]. * **Treatment:** Acute management involves NSAIDs, Colchicine, or intra-articular steroids. Always treat the underlying metabolic cause.

Q: Which antibody is associated with a decreased risk of nephritis in patients with Systemic Lupus Erythematosus?

Anti-SSA. Explanation: In Systemic Lupus Erythematosus (SLE), the presence of **Anti-SSA (Ro) antibodies** is statistically associated with a **decreased risk of developing lupus nephritis**. While these antibodies are linked to specific manifestations like photosensitivity, subacute cutaneous lupus (SCLE), and Sjögren’s syndrome [1], patients positive for Anti-SSA often follow a more "benign" renal course compared to those with other serological markers. **Analysis of Options:** * **Anti-SSA (Correct):** Associated with a lower incidence of renal involvement [1]. However, it is highly associated with **Neonatal Lupus** (congenital heart block) and **Subacute Cutaneous Lupus Erythematosus (SCLE)** [1]. * **Anti-dsDNA (Incorrect):** This is the hallmark antibody for **Lupus Nephritis**. Its titers correlate with disease activity and the development of glomerulonephritis [1]. * **Anti-Smith (Incorrect):** The most specific antibody for SLE. It is strongly associated with **renal disease** and central nervous system (CNS) involvement [1]. * **Anti-histone (Incorrect):** The classic marker for **Drug-Induced Lupus (DILE)**. Renal and CNS involvement are characteristically rare in DILE, but the antibody itself is not considered "protective" against nephritis in idiopathic SLE. **High-Yield Clinical Pearls for NEET-PG:** * **Most Specific Antibody for SLE:** Anti-Smith [1]. * **Best Screening Test:** ANA (High sensitivity, low specificity) [1]. * **Antibody correlating with Disease Activity:** Anti-dsDNA [1]. * **Antibody in Neonatal Lupus:** Anti-SSA/Ro and Anti-SSB/La. * **Drug-Induced Lupus:** Anti-histone positive; Anti-dsDNA and Anti-Smith are typically negative. Common triggers include Hydralazine, Procainamide, and Isoniazid.

Q: Renal involvement is usually absent in which of the following conditions?

Drug-induced systemic lupus erythematosus (SLE). **Explanation:** The correct answer is **Drug-induced systemic lupus erythematosus (SLE)**. **1. Why Drug-induced SLE is the correct answer:** Drug-induced SLE (DILE) is a syndrome that shares clinical features with idiopathic SLE but is triggered by specific medications (e.g., Hydralazine, Procainamide, Isoniazid). A hallmark of DILE is its **mild clinical course**. Unlike idiopathic SLE, DILE characteristically **spares the kidneys and the Central Nervous System (CNS)**. It typically presents with constitutional symptoms, arthralgia, and serositis. Laboratory findings show **Anti-histone antibodies** in >95% of cases, while Anti-dsDNA and low complement levels (C3, C4) are rare [1]. **2. Why the other options are incorrect:** * **Adult SLE:** Renal involvement (Lupus Nephritis) occurs in approximately 40–50% of adult patients and is a major cause of morbidity and mortality [1]. * **Pediatric SLE:** Childhood-onset SLE tends to be **more aggressive** than adult-onset disease. Renal involvement is more frequent (up to 80%) [2] and often more severe at presentation. * **SLE during Pregnancy:** Pregnancy can trigger flares of SLE. Lupus nephritis is a significant concern during pregnancy as it mimics pre-eclampsia and increases the risk of adverse maternal and fetal outcomes. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common drug causing DILE:** Procainamide (highest risk), but Hydralazine is more commonly used clinically. * **Genetic Predisposition:** "Slow acetylators" are at a higher risk of developing DILE. * **Key Lab Marker:** Anti-histone antibodies (High sensitivity for DILE) [3]. * **Management:** Symptoms usually resolve within weeks of discontinuing the offending drug. * **Mnemonic for DILE drugs (HIP):** **H**ydralazine, **I**soniazid, **P**rocainamide (also Phenytoin, Penicillamine).

Q: A 40-year-old female presents with a history of fever, fatigue, weight loss, and symmetrical polyarthralgia predominantly involving the small joints of the hands and wrists. What is the most likely diagnosis?

Rheumatoid arthritis. ***Rheumatoid arthritis*** - The combination of **systemic symptoms** (fever, fatigue, weight loss) with **symmetrical polyarthralgia** affecting small joints is characteristic of rheumatoid arthritis. - **Middle-aged females** are most commonly affected, and the **hands and wrists** are typical early sites of involvement in this autoimmune condition. *Osteoarthritis* - Primarily a **degenerative joint disease** without systemic features like fever, fatigue, or weight loss. - Typically affects **weight-bearing joints** and **DIP joints**, with **asymmetric** joint involvement rather than symmetrical small joint polyarthralgia. *Gout* - Usually presents as **acute monoarticular arthritis** affecting large joints, particularly the **first metatarsophalangeal joint**. - More common in **males** and lacks the systemic symptoms and symmetrical small joint involvement seen in this case. *Psoriatic arthritis* - Characteristically involves **DIP joints** and has an **asymmetric distribution**, unlike the symmetrical small joint pattern described. - Associated with **psoriatic skin lesions** and **nail changes**, which are not mentioned in this presentation.

Question 1

A 40-year-old female patient presented with bilateral joint pain in the wrists, and the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints. The involved joints were tender and swollen. The patient also reported a history of certain skin lesions that occurred before the joint involvement, along with certain nail changes. Laboratory findings revealed HLA-B27 positivity. Which of the following X-ray findings most commonly correlates with the above condition?

Accepted Answer

Erosive changes with joint space narrowing

Answer

Periostitis and proliferative changes

Answer

Saw-tooth appearance of the joints

Answer

All of the above findings are seen.

Question 2

Moderate to high titres of anti-DNA and anti-Smith antibodies are almost pathognomonic of which condition?

Accepted Answer

Systemic Lupus Erythematosus (SLE)

Answer

Erythema Multiforme (EM)

Answer

Lichen planus

Answer

All of the above

Question 3

Which one of the following is not included in Jones's Major criteria?

Accepted Answer

High ESR

Answer

Pancarditis

Answer

Chorea

Answer

Subcutaneous nodule

Question 4

Which is the most common site of subcutaneous nodules in rheumatoid arthritis?

Accepted Answer

Elbow

Answer

Wrist

Answer

Achilles tendon

Answer

Occiput

Question 5

A 48-year-old man complains of joint pain and stiffness for the past three months. All of the following are evidence of the diagnosis of rheumatoid arthritis (RA), EXCEPT?

Accepted Answer

Synovial fluid with high viscosity and 30,000 lymphocytes/mm3

Answer

Early morning stiffness lasting one hour

Answer

Numbness and blanching of fingers on exposure to cold

Answer

Symmetrical involvement of the metacarpophalangeal joints

Question 6

Reiter's syndrome is associated with which of the following causative agents?

Accepted Answer

Chlamydia

Answer

Neisseria

Answer

Mycoplasma

Answer

Herpes virus

Question 7

A lady presents with right knee swelling. Aspiration revealed the presence of calcium pyrophosphate dihydrate (CPPD) crystals. What is the next best investigation?

Accepted Answer

Thyroid-stimulating hormone (TSH)

Answer

Antinuclear antibody (ANA)

Answer

Rheumatoid factor (RF)

Answer

Creatine phosphokinase (CPK)

Question 8

Which antibody is associated with a decreased risk of nephritis in patients with Systemic Lupus Erythematosus?

Accepted Answer

Anti-SSA

Answer

Anti-dsDNA

Answer

Anti-Smith

Answer

Anti-histone

Question 9

Renal involvement is usually absent in which of the following conditions?

Accepted Answer

Drug-induced systemic lupus erythematosus (SLE)

Answer

Adult SLE

Answer

Pediatric SLE

Answer

SLE during pregnancy

Question 10

A 40-year-old female presents with a history of fever, fatigue, weight loss, and symmetrical polyarthralgia predominantly involving the small joints of the hands and wrists. What is the most likely diagnosis?

Accepted Answer

Rheumatoid arthritis

Answer

Osteoarthritis

Answer

Gout

Answer

Psoriatic arthritis

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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