Rheumatology and Immunology Practice Questions

Q: Which disease characteristically involves the distal interphalangeal joint?

Psoriatic arthritis. The involvement of the **Distal Interphalangeal (DIP) joints** is a classic hallmark of **Psoriatic Arthritis (PsA)**, occurring in approximately 40-50% of patients [1]. This is often associated with characteristic psoriatic nail changes (pitting, onycholysis) [1]. In PsA, the inflammation occurs at the **enthesis** (where tendons/ligaments insert into bone), which leads to the characteristic "pencil-in-cup" deformity on X-ray and dactylitis ("sausage digit"). **Analysis of Incorrect Options:** * **B. Rheumatoid Arthritis (RA):** RA characteristically **spares the DIP joints** [2]. It primarily involves the Proximal Interphalangeal (PIP) joints, Metacarpophalangeal (MCP) joints, and wrists. * **C. Systemic Lupus Erythematosus (SLE):** SLE causes a non-erosive arthritis (Jaccoud’s arthropathy) that typically affects the PIPs and MCPs, similar to RA, but without bone destruction. * **D. Gout:** While gout can affect any joint, it most commonly presents as podagra (1st MTP joint). DIP involvement is rare unless the patient has underlying osteoarthritis (nodal gout). **NEET-PG High-Yield Pearls:** 1. **DIP Joint Differential:** The two most common causes of DIP involvement are **Osteoarthritis** (Heberden’s nodes) and **Psoriatic Arthritis** [1]. 2. **Radiology of PsA:** Look for the "Pencil-in-cup" deformity and "Telescoping" of digits (arthritis mutilans) [1]. 3. **CASPAR Criteria:** Used for the diagnosis of PsA; it includes skin psoriasis, nail lesions, dactylitis, and negative Rheumatoid Factor (RF). 4. **Sausage Digit:** Dactylitis is a key feature of Spondyloarthropathies (like PsA) but is absent in RA.

Q: All of the following are increased in rheumatoid arthritis, except?

Synovial fluid viscosity. **Explanation:** In Rheumatoid Arthritis (RA), the hallmark of joint involvement is **inflammatory synovitis**. This inflammatory process directly alters the composition of synovial fluid, leading to a **decrease in synovial fluid viscosity** [1]. 1. **Why Synovial Fluid Viscosity is Decreased:** Normal synovial fluid is highly viscous due to a high concentration of **Hyaluronan (Hyaluronic acid)**. In RA, the inflamed synovium produces inflammatory cytokines and enzymes that degrade hyaluronan [1]. Additionally, the rapid influx of neutrophils and increased fluid volume (effusion) dilutes the hyaluronan. This results in "watery" synovial fluid that fails the "string sign" test, making it the correct answer as it decreases rather than increases. 2. **Analysis of Other Options:** * **ESR (Erythrocyte Sedimentation Rate):** This is an acute-phase reactant. In active RA, systemic inflammation leads to increased production of fibrinogen, which causes RBCs to stack (rouleaux formation), thereby **increasing** the ESR [2]. * **Rheumatoid Factor (RF):** An autoantibody (usually IgM) directed against the Fc portion of IgG [3]. It is **increased** (positive) in approximately 70-80% of RA patients [2]. * **Anti-CCP Antibodies:** These are highly specific for RA. Their levels are **increased** and are often used for early diagnosis and predicting aggressive disease [2]. **Clinical Pearls for NEET-PG:** * **Synovial Fluid Analysis:** In RA, the fluid is inflammatory (WBC count typically 2,000–50,000/mm³). * **Most Specific Marker:** Anti-CCP (Cyclic Citrullinated Peptide) is more specific for RA than RF [2]. * **Poor Prognostic Factors:** High titers of RF/Anti-CCP, presence of HLA-DR4, and early erosions on X-ray. * **String Sign:** Normal synovial fluid forms a 3–5 cm string; in RA, this string breaks immediately due to low viscosity.

Q: What is the Rh factor?

IgM antibody. **Explanation:** The **Rh factor** (specifically the D antigen) is a protein found on the surface of red blood cells. However, in the context of clinical immunology and blood banking, the term "Rh factor" is also historically associated with the **Rheumatoid Factor (RF)** in some older medical nomenclature, though they are distinct entities. In the context of this specific question, the "Rh factor" refers to **Rheumatoid Factor**, which is an autoantibody. 1. **Why A is correct:** Rheumatoid Factor is classically an **IgM antibody** directed against the Fc portion of the patient's own IgG. It is a key diagnostic marker for Rheumatoid Arthritis. 2. **Why B is incorrect:** Mucopolysaccharides (glycosaminoglycans) are carbohydrate chains found in connective tissues; they do not constitute antibodies or blood group antigens. 3. **Why C is incorrect:** While RF can occasionally be IgG or IgA, the **standard diagnostic "Rh factor" is IgM**. Note: Do not confuse this with *anti-D antibodies* (formed during Rh sensitization in pregnancy), which are indeed IgG and can cross the placenta. 4. **Why D is incorrect:** Fatty acids are components of lipids and have no structural relationship to immune globulins or surface antigens. **High-Yield Clinical Pearls for NEET-PG:** * **Rh Blood Group:** The D antigen is the most immunogenic. Anti-D antibodies are **IgG** (warm antibodies), which is why they cause Hemolytic Disease of the Newborn (HDN). * **Rheumatoid Factor (RF):** It is an **IgM against the Fc fragment of IgG**. It is found in 70-80% of RA patients but is not pathognomonic (also seen in SLE, Sjögren's, and chronic infections). * **Rose-Waaler Test:** A classic hemagglutination test used to detect Rheumatoid Factor.

Q: This lesion is most commonly seen in which disease?

Psoriatic Arthritis. ***Psoriatic Arthritis*** - **Psoriatic plaques** with silvery-white scales on an erythematous base are the classic skin manifestation strongly associated with psoriatic arthritis. - **Nail pitting** and **onycholysis** (nail separation) are characteristic nail changes that occur in up to 80% of patients with psoriatic arthritis. *Rheumatoid Arthritis* - Does not typically present with **psoriatic skin lesions** or characteristic nail changes. - Skin manifestations are limited to **rheumatoid nodules** over bony prominences, not scaly plaques. *Ankylosing spondylitis* - Primarily affects the **axial skeleton** without characteristic skin lesions like psoriatic plaques. - May have **uveitis** or **inflammatory bowel disease** associations, but not dermatological manifestations. *Gout* - Characteristic lesions are **tophi** (uric acid crystal deposits), not psoriatic plaques. - Skin changes include **chalky white deposits** around joints, particularly the ears and fingers, distinct from scaly erythematous plaques.

Q: What is the first-choice disease-modifying antirheumatic drug (DMARD) in rheumatoid arthritis?

Methotrexate. **Explanation:** **Methotrexate (MTX)** is the "Anchor Drug" and the first-line Disease-Modifying Antirheumatic Drug (DMARD) for Rheumatoid Arthritis (RA). Its status as the gold standard is due to its proven efficacy, favorable safety profile, low cost, and ability to reduce radiological progression of the disease. * **Mechanism:** It is a folate antimetabolite that inhibits the enzyme **dihydrofolate reductase**. In RA, its anti-inflammatory effect is primarily mediated by increasing extracellular **adenosine** levels, which inhibits T-cell activation. * **Administration:** It is typically started at 7.5–15 mg once weekly (never daily) along with Folic acid supplementation to reduce gastrointestinal and mucosal side effects. **Why other options are incorrect:** * **Gold salts & Penicillamine:** These are "historical DMARDs." While effective, they are rarely used today due to significant toxicities (e.g., nephrotic syndrome, bone marrow suppression) and the availability of safer alternatives. * **Sulfasalazine:** While a valid conventional synthetic DMARD (csDMARD), it is generally considered second-line or used as part of "Triple Therapy" (Methotrexate + Sulfasalazine + Hydroxychloroquine). It is often the preferred choice in pregnant patients where MTX is contraindicated. **High-Yield Clinical Pearls for NEET-PG:** * **Monitoring:** Baseline CBC, LFTs, and Renal Function Tests are mandatory. Watch for **hepatotoxicity** (fibrosis) and **pneumonitis**. * **Contraindications:** Pregnancy (Category X - Teratogenic), chronic liver disease, and severe renal failure. * **Fastest Acting:** Among conventional DMARDs, MTX has a relatively quick onset (4–6 weeks). * **Leflunomide** is the best alternative if a patient is intolerant to Methotrexate.

Question 1

Which disease characteristically involves the distal interphalangeal joint?

Accepted Answer

Psoriatic arthritis

Answer

Rheumatoid arthritis

Answer

Systemic lupus erythematosus

Answer

Gout

Question 2

A patient complains of hematuria. Renal biopsy demonstrates a focal necrotizing glomerulonephritis with crescent formation. The patient also complains of decreased sensation in the hands and feet. What is the next best investigation to diagnose the condition?

Accepted Answer

Antineutrophil cytoplasmic antibodies (ANCA)

Answer

MIF (Microscopic Immunofluorescence)

Answer

Hepatitis B surface antigen (HbsAg)

Answer

Rheumatoid factor (RA factor)

Question 3

All of the following are increased in rheumatoid arthritis, except?

Accepted Answer

Synovial fluid viscosity

Answer

ESR levels

Answer

Rheumatoid factor

Answer

Anti-CCP Antibodies

Question 4

During the winter months, a 65-year-old man presents with livedo reticularis and purple fingertips. Other symptoms include arthralgia and weakness. Renal impairment is present on laboratory testing. Which of the following is the most likely diagnosis?

Accepted Answer

cryoglobulinemia

Answer

cold agglutinin disease

Answer

Henoch-Schonlein purpura

Answer

antiphospholipid antibody syndrome

Question 5

Which of the following conditions does NOT typically cause bone erosion?

Accepted Answer

Systemic Lupus Erythematosus (SLE)

Answer

Psoriasis

Answer

Rheumatoid Arthritis (RA)

Answer

Gout

Question 6

A 19-year-old man has a chronic papulosquamous skin disorder involving his knees and elbows. He now has dull low back pain and morning stiffness that lasts a few hours. On examination, forward flexion at the lumbar spine is reduced, but neck movements are normal. There is stress tenderness of both sacroiliac joints. Which of the following is the most likely diagnosis?

Accepted Answer

Psoriatic arthritis

Answer

Rheumatoid arthritis

Answer

Ankylosing spondylitis

Answer

Reactive arthritis

Question 7

What is the Rh factor?

Accepted Answer

IgM antibody

Answer

Mucopolysaccharide

Answer

IgG antibody

Answer

Fatty acid

Question 8

A 25-year-old normotensive patient presents to the emergency department with breathlessness and palpitations. The patient has a history of allergy to peanuts and accidentally ingested them. On examination, the patient's heart rate is 120/min and blood pressure is 100/60 mm Hg. An urgent X-ray was performed. What is the most likely diagnosis?

Accepted Answer

Non-cardiogenic pulmonary edema

Answer

Cardiogenic pulmonary edema

Answer

Pulmonary embolism

Answer

Atrial septal defect

Question 9

This lesion is most commonly seen in which disease?

Accepted Answer

Psoriatic Arthritis

Answer

Rheumatoid Arthritis

Answer

Ankylosing spondylitis

Answer

Gout

Question 10

What is the first-choice disease-modifying antirheumatic drug (DMARD) in rheumatoid arthritis?

Accepted Answer

Methotrexate

Answer

Gold salts

Answer

Penicillamine

Answer

Sulfasalazine

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

On this page

Practice by Chapter

Want unlimited practice?