Rheumatology and Immunology Practice Questions

Q: Which antibody is implicated in the pathogenesis of Henoch-Schönlein purpura?

IgA. **Explanation:** **Henoch-Schönlein Purpura (HSP)**, now commonly referred to as **IgA Vasculitis**, is a small-vessel vasculitis characterized by the deposition of immune complexes containing **IgA1** [1]. 1. **Why IgA is Correct:** The hallmark of HSP pathogenesis is the deposition of **galactose-deficient IgA1 (Gd-IgA1)** in the walls of small vessels (capillaries, venules, and arterioles). These abnormal IgA molecules act as autoantigens, leading to the formation of glycan-specific IgG autoantibodies. The resulting immune complexes deposit in the skin, joints, gastrointestinal tract, and renal mesangium, triggering an inflammatory response (leukocytoclastic vasculitis) [1]. 2. **Why other options are incorrect:** * **IgG:** While IgG autoantibodies may bind to the abnormal IgA1, they are not the primary initiating antibody. IgG is more typically associated with systemic lupus erythematosus (SLE) or ANCA-associated vasculitides [2]. * **IgM:** IgM is the primary antibody in the early immune response and is found in Cryoglobulinemic vasculitis, but it does not play a central role in HSP. * **IgD:** This antibody is primarily found on the surface of B cells and has no known role in the pathogenesis of systemic vasculitis. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Tetrad:** Palpable purpura (without thrombocytopenia), arthralgia/arthritis, abdominal pain (colicky), and renal disease (hematuria) [1]. * **Renal Pathology:** On light microscopy, it is indistinguishable from **IgA Nephropathy (Berger’s disease)**; both show mesangial IgA deposits. * **Trigger:** Often follows an **Upper Respiratory Tract Infection (URTI)** [1]. * **Diagnosis:** Primarily clinical; skin biopsy shows **leukocytoclastic vasculitis** with IgA and C3 deposition on immunofluorescence.

Q: Xerostomia and Xerophthalmia are characteristic features of which condition?

Sjogren syndrome. **Explanation:** **Sjogren Syndrome (Option A)** is a chronic autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands. The hallmark clinical features are **Xerostomia** (dry mouth due to salivary gland dysfunction) and **Xerophthalmia** (dry eyes due to lacrimal gland dysfunction), collectively known as **Sicca syndrome**. It can occur alone (Primary) or in association with other connective tissue diseases like Rheumatoid Arthritis (Secondary). **Analysis of Incorrect Options:** * **Riley-Day Syndrome (Option B):** Also known as Familial Dysautonomia, it is characterized by a *lack* of tears (alacrima) and sensory deficits, but it is a rare genetic autonomic neuropathy, not a primary autoimmune sicca complex. * **Stevens-Johnson Syndrome (Option C):** This is a severe mucocutaneous hypersensitivity reaction (often drug-induced) characterized by epidermal necrolysis and sloughing. While it affects mucous membranes, it presents acutely with bullae and skin peeling rather than chronic glandular insufficiency. * **Vitamin A Deficiency (Option D):** While it causes Xerophthalmia (specifically Bitot’s spots and keratomalacia), it does not typically cause Xerostomia. **NEET-PG High-Yield Pearls:** * **Antibodies:** Highly specific for **Anti-Ro (SS-A)** and **Anti-La (SS-B)**. * **Diagnostic Test:** **Schirmer’s test** (measures tear production) and **Lip biopsy** (showing focal lymphocytic sialadenitis) are gold standards. * **Malignancy Risk:** Patients have a 40-fold increased risk of developing **B-cell MALT Lymphoma** (look for persistent parotid swelling). * **Extraglandular features:** May include Raynaud’s phenomenon, cutaneous vasculitis, and interstitial nephritis.

Q: What color change does a patient with Raynaud's disease experience in their hands when exposed to cold water?

White. **Explanation:** Raynaud’s phenomenon is a vasospastic disorder characterized by episodic digital ischemia in response to cold or emotional stress. The classic presentation involves a **triphasic color change**, and the **initial** phase is always **White (Pallor)**. 1. **Why White is Correct:** When exposed to cold, there is intense vasoconstriction of the digital arteries and precapillary arterioles. This sudden cessation of blood flow to the skin causes the fingers to turn chalky white (pallor). This is the hallmark initial sign of the condition. 2. **Why other options are incorrect:** * **Blue (Cyanosis):** This is the *second* phase. It occurs due to deoxygenation of the static blood remaining in the capillaries during the ischemic period. * **Yellow:** This is not a recognized clinical stage of Raynaud’s. * **Black:** This indicates digital gangrene or necrosis, which is a complication of severe secondary Raynaud’s (e.g., in Systemic Sclerosis) rather than a standard color change of the disease itself. **Clinical Pearls for NEET-PG:** * **The Triphasic Sequence:** White (Ischemia) → Blue (Hypoxia) → Red (Reactive Hyperemia/Reperfusion). * **Primary vs. Secondary:** Primary Raynaud’s (Raynaud’s Disease) is idiopathic and usually symmetric. Secondary Raynaud’s (Raynaud’s Phenomenon) is often associated with connective tissue diseases, most commonly **Systemic Sclerosis (Scleroderma)**. * **Drug of Choice:** Calcium Channel Blockers (specifically **Nifedipine**) are the first-line treatment. * **Capillaroscopy:** Nailfold capillaroscopy is a high-yield diagnostic tool used to differentiate primary from secondary causes by looking for enlarged or "dropout" capillary loops.

Q: In which of the following conditions is interstitial lung disease least common?

Dermatomyositis. **Explanation:** The correct answer is **Dermatomyositis**. However, there is a significant clinical nuance to address: while Dermatomyositis is frequently associated with Interstitial Lung Disease (ILD) in clinical practice (up to 40% of cases), **Systemic Lupus Erythematosus (SLE)** is statistically the condition where chronic progressive ILD is **least common** among the major connective tissue diseases (CTDs) [1]. **1. Why SLE is the correct conceptual answer:** In SLE, the primary pulmonary involvements are **pleuritis and pleural effusion** (the most common) or acute lupus pneumonitis. Chronic fibrotic ILD is rare in SLE (occurring in <5% of patients) [1]. In contrast, ILD is a hallmark complication and a major cause of mortality in Scleroderma, Rheumatoid Arthritis, and Dermatomyositis [1]. **2. Analysis of other options:** * **Scleroderma (Systemic Sclerosis):** ILD is extremely common, especially in the diffuse cutaneous subtype (up to 80% on HRCT). It is a leading cause of death [1]. * **Rheumatoid Arthritis (RA):** ILD is a well-recognized extra-articular manifestation, particularly in older males with high-titer Rheumatoid Factor and smoking history. * **Dermatomyositis/Polymyositis:** These are strongly associated with ILD, particularly in patients positive for **anti-Jo-1 antibodies** (Antisynthetase syndrome) or **anti-MDA5 antibodies**. **Clinical Pearls for NEET-PG:** * **Most common pulmonary manifestation in SLE:** Pleuritis [1]. * **Most common CTD-ILD pattern:** NSIP (Non-Specific Interstitial Pneumonia), *except* in RA, where UIP (Usual Interstitial Pneumonia) is more frequent. * **Antisynthetase Syndrome Triad:** Myositis, ILD, and "Mechanic’s hands." * **Drug-induced ILD:** Methotrexate (used in RA) can also cause acute pneumonitis, which must be differentiated from RA-associated ILD [1].

Q: All of the following are true regarding acute gouty arthritis, EXCEPT:

Allopurinol is effective to treat the acute attack. The correct answer is **A. Allopurinol is effective to treat the acute attack.** **1. Why Option A is correct (The False Statement):** Allopurinol is a **Xanthine Oxidase Inhibitor** used for chronic management (urate-lowering therapy) [1]. It should **never** be initiated during an acute attack. Rapidly lowering serum urate levels can cause the mobilization of urate from tissue stores, leading to the "shedding" of crystals into the joint space, which paradoxically worsens or prolongs the acute inflammation [1]. The primary goal in an acute attack is to reduce inflammation using NSAIDs, Colchicine, or Glucocorticoids. **2. Analysis of Incorrect Options:** * **Option B:** Monosodium urate (MSU) crystals are characteristically **needle-shaped** and show **strong negative birefringence** under polarized light (appearing yellow when parallel to the slow axis of the compensator) [2]. * **Option C:** Serum uric acid levels are unreliable during an acute flare. They may be **normal or low** because uric acid is an "acute-phase reactant" that can be excreted more rapidly by the kidneys during stress, or because the urate has precipitated out of the blood into the joints [3]. * **Option D:** **Tophi** are pathognomonic for chronic gout and consist of large aggregations of MSU crystals surrounded by a granulomatous inflammatory response [2]. **Clinical Pearls for NEET-PG:** * **First-line for acute gout:** NSAIDs (e.g., Indomethacin, Naproxen). * **Colchicine:** Most effective if started within 12–24 hours; its main side effect is diarrhea. * **Rule of Initiation:** If a patient is already on Allopurinol when an attack starts, **do not stop it**. If they are not on it, **do not start it** until the inflammation has completely subsided (usually 2 weeks later) [1]. * **Definitive Diagnosis:** Arthrocentesis showing needle-shaped, negatively birefringent crystals [2].

Q: A patient has been diagnosed with systemic sclerosis and has the presence of anti-RNA polymerase III antibodies. Which of the following is more commonly associated with this condition?

Acute onset of disease. Explanation: Systemic Sclerosis (SSc) is categorized into limited and diffuse types based on skin involvement and autoantibody profiles. **Anti-RNA polymerase III (anti-RNAP III)** antibodies are highly specific for the **Diffuse Cutaneous Systemic Sclerosis (dcSSc)** subtype. **1. Why "Acute onset of disease" is correct:** Anti-RNAP III antibodies are associated with a rapid and aggressive clinical course. Patients typically present with an **acute or subacute onset** of extensive skin thickening (scleroderma) that progresses rapidly over the trunk and proximal extremities [1]. **2. Analysis of Incorrect Options:** * **A. Reduced risk of scleroderma renal crisis:** This is incorrect. Anti-RNAP III is the strongest predictor for **Scleroderma Renal Crisis (SRC)**. Patients with these antibodies require frequent blood pressure monitoring. * **C. Reduced risk of malignancy:** This is incorrect. There is a well-documented temporal association between the onset of anti-RNAP III-positive SSc and **synchronous malignancy** (especially breast and GI cancers), suggesting a paraneoplastic trigger. * **D. Increased risk of pulmonary hypertension:** While it can occur, isolated Pulmonary Arterial Hypertension (PAH) is more classically associated with **Limited SSc** and **Anti-centromere antibodies**. Anti-RNAP III is more closely linked to skin and renal involvement. **High-Yield Clinical Pearls for NEET-PG:** * **Anti-Scl-70 (Anti-topoisomerase I):** Associated with Diffuse SSc and a high risk of **Interstitial Lung Disease (ILD)**. * **Anti-Centromere:** Associated with Limited SSc (CREST syndrome) and **Pulmonary Hypertension**. * **Anti-U1 RNP:** Associated with **Mixed Connective Tissue Disease (MCTD)**. * **Management Tip:** In patients with anti-RNAP III, avoid high-dose corticosteroids as they can precipitate a renal crisis.

Q: Which HLA antigen is most strongly associated with Behcet disease?

B51. **Explanation:** **Behcet Disease (BD)** is a multisystemic, chronic relapsing inflammatory perivasculitis characterized by the classic triad of oral ulcers, genital ulcers, and uveitis. The strongest genetic risk factor identified globally for Behcet disease is the **HLA-B51** allele (a subtype of HLA-B5). Patients carrying this allele have a significantly higher relative risk (nearly 6-fold) of developing the disease compared to the general population. It is particularly prevalent in populations along the "Silk Road" (Middle East and East Asia). **Analysis of Options:** * **A. B51 (Correct):** As established, HLA-B51 is the primary genetic marker for Behcet disease and is often associated with a more severe clinical course, including ocular involvement. * **B. B27:** This is strongly associated with **Seronegative Spondyloarthropathies** (e.g., Ankylosing Spondylitis, Reactive Arthritis, Psoriatic Arthritis, and IBD-associated arthritis) [1]. * **C. DRQ:** This is likely a distractor or a typo for HLA-DQ. HLA-DQ2/DQ8 are associated with Celiac disease. * **D. DDR4:** Likely a typo for **HLA-DR4**, which is the classic association for **Rheumatoid Arthritis** (specifically the "shared epitope"). **High-Yield Clinical Pearls for NEET-PG:** * **Pathergy Test:** A unique diagnostic feature where a sterile skin papule or pustule forms 24–48 hours after a needle prick. It is highly specific for Behcet disease. * **Vascular Involvement:** Unlike many other vasculitides, Behcet can involve both **arteries and veins** of all sizes (e.g., pulmonary artery aneurysms and Budd-Chiari syndrome). * **Hypopyon Uveitis:** A classic ocular finding in Behcet disease characterized by a layer of white blood cells in the anterior chamber.

Question 1

Which antibody is implicated in the pathogenesis of Henoch-Schönlein purpura?

Accepted Answer

IgA

Answer

IgG

Answer

IgM

Answer

IgD

Question 2

A 50-year-old female patient with a known history of hepatitis C presents with joint pains, myalgia, fatigue, recurrent skin infections, and symptoms of peripheral neuropathy. On examination, she has acrocyanosis, livedo reticularis, and purpura. Lab studies reveal deranged renal function tests with proteinuria, leukocytosis, positive ANA, raised ESR, and kidney biopsy findings. What is the diagnosis?

Accepted Answer

Essential mixed cryoglobulinemia

Answer

Membranoproliferative glomerulonephritis (MPGN)

Answer

Mesangial glomerulonephritis (MGN)

Answer

IgA nephropathy

Question 3

Xerostomia and Xerophthalmia are characteristic features of which condition?

Accepted Answer

Sjogren syndrome

Answer

Riley-Day syndrome

Answer

Stevens-Johnson syndrome

Answer

Vitamin A deficiency

Question 4

What color change does a patient with Raynaud's disease experience in their hands when exposed to cold water?

Accepted Answer

White

Answer

Yellow

Answer

Blue

Answer

Black

Question 5

A 40-year-old man presents with malaise, fatigue, dyspnea on exertion, cardiomegaly on chest X-ray, a 10 kg weight loss, mononeuritis, and polyarthritis. What is the most likely diagnosis?

Accepted Answer

Neurosarcoidosis

Answer

Polyarteritis nodosa (PAN)

Answer

Systemic lupus erythematosus (SLE)

Answer

Neuro AIDS

Question 6

In which of the following conditions is interstitial lung disease least common?

Accepted Answer

Dermatomyositis

Answer

Systemic lupus erythematosus (SLE)

Answer

Scleroderma

Answer

Rheumatoid arthritis

Question 7

A 29-year-old man complains of back pain for several months. It takes him over 2 hours to limber up in the morning. Which of the following is the most likely diagnosis?

Accepted Answer

Ankylosing spondylitis

Answer

Rheumatoid arthritis

Answer

Spondylolisthesis

Answer

Osteomalacia

Question 8

All of the following are true regarding acute gouty arthritis, EXCEPT:

Accepted Answer

Allopurinol is effective to treat the acute attack

Answer

MSU crystals are needle shaped and negatively birefringent

Answer

Serum uric acid levels can be normal or low at the time of an acute attack

Answer

Tophi are made up of monosodium urate crystals (MSU)

Question 9

A patient has been diagnosed with systemic sclerosis and has the presence of anti-RNA polymerase III antibodies. Which of the following is more commonly associated with this condition?

Accepted Answer

Acute onset of disease

Answer

Reduced risk of scleroderma renal crisis

Answer

Reduced risk of malignancy

Answer

Increased risk of pulmonary hypertension

Question 10

Which HLA antigen is most strongly associated with Behcet disease?

Accepted Answer

B51

Answer

B27

Answer

DRQ

Answer

DDR4

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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