Rheumatology and Immunology — MCQs

Rheumatology and Immunology Indian Medical PG Practice Questions and MCQs

Question 851: Which joint is most commonly affected in ankylosing spondylitis?

A. Sacroiliac (Correct Answer)
B. Elbow
C. Knee
D. Ankle

Explanation: ***Sacroiliac*** - The **sacroiliac joints** are almost universally involved in ankylosing spondylitis, making them the most commonly affected [1]. - Inflammation and fusion of these joints are hallmark features, leading to **low back pain** and stiffness [1]. *Elbow* - The elbow joint is **uncommonly affected** in ankylosing spondylitis. - Peripheral joint involvement in ankylosing spondylitis is typically less frequent than axial involvement. *Knee* - While peripheral joints can be affected, the **knee is not the most commonly affected joint** in ankylosing spondylitis compared to the axial skeleton. - When involved, it tends to be less severe and less frequent than sacroiliac involvement. *Ankle* - The ankle joint is **uncommonly involved** in ankylosing spondylitis. - Peripheral joint inflammation is more often directed towards the lower limbs, but the **sacroiliac joints remain primary**.

Question 852: A 55-year-old man presents with muscle weakness and elevated creatine kinase levels. Muscle biopsy reveals endomysial inflammation. What is the most likely diagnosis?

A. Dermatomyositis
B. Polymyositis (Correct Answer)
C. Inclusion body myositis
D. Rhabdomyolysis

Explanation: ***Polymyositis*** - Characterized by **proximal muscle weakness** and **elevated creatine kinase (CK)**, which are classic signs of inflammatory myopathy [1]. - The key diagnostic feature in polymyositis is **endomysial inflammation** with cytotoxic T-cells invading non-necrotic muscle fibers on muscle biopsy [3]. *Dermatomyositis* - While also an inflammatory myopathy with similar muscle weakness and elevated CK, it is distinguished by characteristic **skin rashes** (e.g., heliotrope rash, Gottron's papules) which are not mentioned here [2]. - Biopsy typically shows **perimysial and perivascular inflammation** with B-cells and macrophages, rather than endomysial. *Inclusion body myositis* - This condition is usually seen in older individuals, but the biopsy would reveal **rimmed vacuoles** and **intranuclear/intracytoplasmic inclusions** in addition to endomysial inflammation [3]. - Often presents with **asymmetric weakness**, particularly affecting forearm flexors and quadriceps, and progresses more slowly. *Rhabdomyolysis* - Involves rapid **muscle breakdown** leading to very high CK levels, muscle pain, and often **myoglobinuria**, which would manifest as dark urine. - While it causes muscle weakness, the primary pathological finding is **muscle fiber necrosis** without a prominent inflammatory infiltrate like that seen in polymyositis.

Question 853: A 55-year-old woman presents with firm, indurated plaques on her face and hands, and she also has Raynaud's phenomenon. What is the most likely diagnosis?

A. Systemic lupus erythematosus
B. Scleroderma (Correct Answer)
C. Dermatomyositis
D. Sarcoidosis

Explanation: ***Scleroderma*** - **Firm, indurated plaques** on the face and hands are characteristic of **skin thickening** seen in systemic sclerosis [1]. - **Raynaud's phenomenon** is a very common initial symptom in scleroderma, often preceding other manifestations. *Systemic lupus erythematosus* - While it can cause skin lesions, they typically manifest as a **malar rash** or discoid lesions, not firm, indurated plaques [3]. - Raynaud's can occur, but the combination of specific skin findings points away from SLE as the most likely diagnosis. *Dermatomyositis* - Characterized by **proximal muscle weakness** and specific skin findings like **Gottron's papules** and the **heliotrope rash** [2]. - The described **firm, indurated plaques** are not typical of dermatomyositis. *Sarcoidosis* - May present with various skin lesions, including plaques, but these are usually **erythematous** or violaceous and histologically show **non-caseating granulomas**. - **Raynaud's phenomenon** is not a primary or common feature of sarcoidosis.

Question 854: A 25-year-old woman presents with multiple recurrent infections. Laboratory tests reveal low IgA and normal levels of other immunoglobulins. What is the most likely diagnosis?

A. Common variable immunodeficiency
B. Selective IgA deficiency (Correct Answer)
C. Hyper-IgM syndrome
D. Severe combined immunodeficiency

Explanation: ***Selective IgA deficiency*** - Characterized by low levels of **IgA**, leading to increased susceptibility to infections, particularly in the **respiratory and gastrointestinal** tracts [1]. - The presence of normal levels of other **immunoglobulins** supports this diagnosis as it distinguishes it from other immunodeficiencies [1]. *Common variable immunodeficiency* - This condition typically presents with **low levels of multiple immunoglobulins**, not just **IgA**, and is associated with a higher risk for **autoimmunity and malignancy**. - Patients often have recurrent infections, but the **immunoglobulin profile** differs significantly from selective IgA deficiency [1]. *Hyper-IgM syndrome* - This disorder is characterized by **elevated IgM levels** with low IgG and IgA, leading to a different set of recurrent infections and **opportunistic pathogens**. - Patients have defects in **class switching** of antibodies, which is not the case with isolated low IgA. *Severe combined immunodeficiency* - A more severe condition involving both **cell-mediated** and **humoral immunity** deficits, presenting with very low or absent levels of **T and B cells** [1]. - Symptoms typically arise in infants, including **failure to thrive** and severe infections, which differ from this patient's profile [1].

Question 855: A 25-year-old male with ankylosing spondylitis reports increased morning stiffness and back pain despite the use of NSAIDs. What is the most appropriate next step in management to prevent disease progression?

A. Initiate anti-TNF therapy (Correct Answer)
B. Increase dose of NSAIDs
C. Begin physical therapy
D. Add methotrexate

Explanation: ***Initiate anti-TNF therapy*** - For patients with **ankylosing spondylitis** who have persistent symptoms and evidence of inflammation despite optimal NSAID therapy, **anti-TNF agents** (biologics) are the first-line treatment to control disease activity and prevent structural progression [1]. - These medications target **tumor necrosis factor-alpha (TNF-α)**, a key cytokine in the inflammatory pathway of spondyloarthritis. *Increase dose of NSAIDs* - While NSAIDs are the first-line treatment for symptomatic relief in AS, increasing the dose further when a patient is already experiencing persistent symptoms on adequate NSAID therapy is unlikely to achieve disease control or prevent **structural damage**. - Long-term use of high-dose NSAIDs carries risks of **gastrointestinal, cardiovascular, and renal adverse effects**. *Begin physical therapy* - **Physical therapy** is an essential part of AS management for maintaining flexibility, improving posture, and reducing pain; however, it is adjunctive to pharmacotherapy and does not directly *prevent disease progression* or control inflammation in the way biologics do when NSAIDs fail. - Engaging in physical therapy alone will not adequately address the underlying inflammatory process responsible for structural damage. *Add methotrexate* - **Methotrexate** is a **disease-modifying antirheumatic drug (DMARD)** effective in peripheral arthritis associated with spondyloarthritis and rheumatoid arthritis, but it has **limited efficacy** for axial (spinal) involvement in AS [2]. - It is generally not recommended as monotherapy or an add-on during axial involvement for preventing primary disease progression in AS when NSAIDs have failed.

Question 856: A 30-year-old female presents with fatigue, joint pain, and a facial rash. Which serological test is the most specific for diagnosing systemic lupus erythematosus?

A. Rheumatoid factor
B. Antinuclear antibody (ANA) test
C. Anti-Smith antibody (Correct Answer)
D. Anti-cyclic citrullinated peptide antibody

Explanation: ***Anti-Smith antibody*** - **Anti-Smith antibodies** are highly specific for **Systemic Lupus Erythematosus (SLE)**, almost exclusively found in patients with this condition [1]. - While not as sensitive as ANA, its presence is a strong indicator for diagnosing SLE, particularly in patients presenting with a classic constellation of symptoms like **fatigue, joint pain, and a facial rash** [2]. *Rheumatoid factor* - **Rheumatoid factor (RF)** is primarily associated with **Rheumatoid Arthritis** and is not specific for SLE, though it can be present in a small percentage of SLE patients. - Its presence alone would not confirm an SLE diagnosis and would rather point towards other autoimmune etiologies. *Antinuclear antibody (ANA) test* - An **ANA test** is highly sensitive for **SLE**, meaning most SLE patients will have a positive ANA result [1], [3]. - However, ANA can also be positive in other autoimmune diseases and even in healthy individuals, making it a good screening test but **not specific** for SLE [1]. *Anti-cyclic citrullinated peptide antibody* - **Anti-CCP antibodies** are highly specific for **Rheumatoid Arthritis**, playing a crucial role in its diagnosis and prognosis. - They are not typically associated with SLE and would not be a diagnostic marker for the patient's symptoms.

Question 857: A 65-year-old man presents with pain and swelling in his knee. Joint aspiration reveals positively birefringent rhomboid-shaped crystals. What is the most likely diagnosis?

A. Gout
B. Pseudogout (Correct Answer)
C. Septic arthritis
D. Rheumatoid arthritis

Explanation: ### Pseudogout - **Positively birefringent rhomboid-shaped crystals** in joint fluid are pathognomonic for pseudogout, caused by **calcium pyrophosphate dihydrate (CPPD) deposition** [1]. - **Knee involvement** is common in pseudogout, and the acute inflammatory response leads to pain and swelling [1]. *Gout* - Gout is characterized by **negatively birefringent needle-shaped crystals** of monosodium urate [2], not positively birefringent rhomboid crystals. - While it can affect the knee, gout typically presents with acute, severe pain, often in the **first metatarsophalangeal joint (podagra)**. *Septic arthritis* - Septic arthritis is characterized by the presence of **bacteria** in the joint fluid, often with a very high white blood cell count and low glucose, but not specific crystal findings. - While it causes acute pain and swelling, the definitive diagnosis requires a **positive Gram stain** and **culture** of the synovial fluid. *Rheumatoid arthritis* - Rheumatoid arthritis is an **autoimmune inflammatory arthritis** that typically affects multiple joints symmetrically, often presenting with morning stiffness and joint deformity, but without specific crystal findings in the synovial fluid. - Diagnosis involves clinical criteria, imaging, and lab tests such as **rheumatoid factor** and **anti-CCP antibodies**, and synovial fluid analysis usually shows inflammatory cells but no crystals.

Question 858: A 32-year-old woman with a history of recurrent miscarriages and blood clots is diagnosed with antiphospholipid syndrome. What is the most likely underlying cause?

A. Autoimmune antibodies (Correct Answer)
B. Genetic mutation
C. Vitamin K deficiency
D. Protein C deficiency

Explanation: ***Autoimmune antibodies*** - Antiphospholipid syndrome is primarily driven by the presence of **autoimmune antibodies**, particularly **anticardiolipin antibodies** and **lupus anticoagulant**. - These antibodies lead to increased risk of **thrombosis** and recurrent miscarriages due to their effects on coagulation pathways. *Genetic mutation* - While certain genetic mutations can predispose individuals to thrombophilia, they do not specifically relate to the **autoimmune nature** seen in antiphospholipid syndrome. - The condition is not predominantly caused by **inherited genetic factors**. *Vitamin K deficiency* - Vitamin K deficiency primarily affects the synthesis of **clotting factors II, VII, IX, and X**, not linked to autoimmune mechanisms. - This condition results in a bleeding tendency rather than **thrombotic events** as seen in antiphospholipid syndrome. *Protein C deficiency* - Protein C deficiency leads to a **hypercoagulable state** but is a distinct genetic thrombophilia not related to the presence of **autoimmune antibodies** [1]. - It does not involve **autoimmune processes** that characterize antiphospholipid syndrome [1].

Question 859: A 38-year-old female presents to the clinic with complaints of dry eyes and dry mouth, along with joint pain. An autoimmune workup reveals positive anti-Ro/SSA and anti-La/SSB antibodies. What is the most likely diagnosis?

A. Systemic lupus erythematosus
B. Rheumatoid arthritis
C. Sjögren's syndrome (Correct Answer)
D. Systemic sclerosis

Explanation: Sjögren's syndrome - The classic triad of dry eyes (xerophthalmia), dry mouth (xerostomia), and joint pain (arthralgia) is highly suggestive of Sjögren's syndrome. - The presence of anti-Ro/SSA and anti-La/SSB antibodies is characteristic of Sjögren's syndrome and confirms the diagnosis [1]. Systemic lupus erythematosus - While joint pain and positive anti-Ro/SSA antibodies can be seen in SLE, the primary presentation of prominent severe dry eyes and dry mouth is not its hallmark [1], [2]. - SLE typically involves diverse organ systems (e.g., skin rash, kidney disease, serositis), which are not mentioned here [2]. Rheumatoid arthritis - Rheumatoid arthritis primarily affects the synovial joints, often leading to joint destruction, and does not typically present with the prominent sicca symptoms (dry eyes and mouth) as the main complaint. - It is often associated with rheumatoid factor and anti-CCP antibodies, not anti-Ro/SSA or anti-La/SSB [1]. Systemic sclerosis - Systemic sclerosis is characterized by skin thickening and fibrosis of internal organs, often presenting with Raynaud's phenomenon and esophageal dysmotility. - While it can involve sicca symptoms, the primary clinical picture and antibody profile (e.g., anti-Scl-70, anticentromere) would be different.

Question 860: A 40-year-old woman presents with recurrent episodes of fever, oral ulcers, and arthralgia. Laboratory tests reveal negative ANA, RF, and anti-CCP antibodies. What is the most likely diagnosis?

A. Behcet's disease (Correct Answer)
B. Systemic lupus erythematosus
C. Rheumatoid arthritis
D. Psoriatic arthritis

Explanation: ***Behcet's disease*** - The classic triad of recurrent **oral ulcers**, genital ulcers (not mentioned but common), and **ocular inflammation**, along with recurrent fever and arthralgia, is highly suggestive of Behcet's disease. - The absence of typical autoantibodies like **ANA**, **RF**, and **anti-CCP** further supports this diagnosis, as Behcet's is an **autoinflammatory syndrome** rather than an autoimmune disease with characteristic autoantibodies [2]. *Systemic lupus erythematosus* - While SLE can cause fever, oral ulcers, and arthralgia, it is typically characterized by a **positive ANA** and often other specific antibodies (e.g., anti-dsDNA, anti-Sm), which are negative in this patient [1]. - SLE often presents with additional systemic manifestations such as **malar rash**, photosensitivity, and renal involvement, not described here. *Rheumatoid arthritis* - Rheumatoid arthritis primarily targets the **synovial joints**, leading to chronic inflammatory arthritis, and typically tests positive for **Rheumatoid Factor (RF)** and/or **anti-CCP antibodies**, both of which are negative. - Oral ulcers and recurrent fever are not typical primary manifestations of Rheumatoid Arthritis. *Psoriatic arthritis* - This condition is associated with **psoriasis**, characterized by skin lesions, and typically involves inflamed joints, dactylitis, and enthesitis. - Although it can present with arthralgia, oral ulcers and recurrent fever are not characteristic features, and the widespread skin involvement of psoriasis would usually be evident.

Practice by Chapter

Rheumatoid Arthritis

Practice Questions

Spondyloarthropathies

Practice Questions

Systemic Lupus Erythematosus

Practice Questions

Vasculitis Syndromes

Practice Questions

Scleroderma and Related Disorders

Practice Questions

Inflammatory Myopathies

Practice Questions

Crystal Arthropathies

Practice Questions

Osteoarthritis

Practice Questions

Primary Immunodeficiency Disorders

Practice Questions

Autoinflammatory Syndromes

Practice Questions

Sjögren's Syndrome

Practice Questions

Antiphospholipid Syndrome

Practice Questions

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