Rheumatology and Immunology Practice Questions

Q: A 40-year-old woman with newly diagnosed lupus presents with proteinuria. Which antibody test is the most specific for lupus nephritis?

Anti-dsDNA. ***Anti-dsDNA*** - **Anti-dsDNA antibodies** are highly specific for **Systemic Lupus Erythematosus (SLE)** and their titers often correlate with disease activity, especially **lupus nephritis** [1]. - High levels of **anti-dsDNA antibodies** are found in up to 70% of lupus patients and are particularly implicated in the pathogenesis and severity of **renal involvement** [1]. *ANA* - **Antinuclear antibodies (ANA)** are a very sensitive screening test for lupus, being positive in over 95% of patients, but they are **not specific** to lupus and can be found in other autoimmune diseases or even healthy individuals [1]. - A positive ANA alone does not confirm a diagnosis of lupus or indicate **lupus nephritis** [1]. *Anti-Ro* - **Anti-Ro antibodies** (also known as SS-A) are associated with **subacute cutaneous lupus erythematosus**, **neonatal lupus**, and **Sjogren's syndrome**, as well as a subset of SLE patients [1]. - While present in some lupus patients, they are not specifically linked to **lupus nephritis** as strongly as anti-dsDNA [1]. *Anti-Smith* - **Anti-Smith (Sm) antibodies** are highly specific for SLE, but their prevalence is lower (around 20-30%) compared to other lupus-related antibodies [1]. - While diagnostic for SLE, anti-Sm antibodies do not correlate well with disease activity or specifically with **lupus nephritis** in the same way as anti-dsDNA [1].

Q: In a patient with a history of chronic back pain and morning stiffness that improves with exercise, which radiographic finding is characteristic of ankylosing spondylitis?

Syndesmophytes. ***Syndesmophytes*** - **Syndesmophytes** are characteristic radiographic findings in ankylosing spondylitis, representing ossification within the **annulus fibrosus** and along the outer fibers of the intervertebral disc [1]. - Their presence indicates active disease processes leading to **bony fusion** of vertebrae, contributing to spinal stiffness [1]. *Osteophytes (associated with osteoarthritis)* - **Osteophytes** are bony spurs that form at the margins of joints, primarily associated with **osteoarthritis** due to degenerative changes. - Unlike **syndesmophytes**, they are not specific to inflammatory conditions like ankylosing spondylitis and are typically unilateral and not vertically oriented [1]. *Schmorl's nodes (indicate disc herniation)* - **Schmorl's nodes** are vertebral endplate indentations where the nucleus pulposus herniates into the vertebral body. - While sometimes associated with back pain, they are indicative of **disc degeneration** or trauma, not the inflammatory process of ankylosing spondylitis. *Bamboo spine* - **Bamboo spine** is a descriptive term for the advanced stage of ankylosing spondylitis, resulting from widespread **syndesmophyte formation** and fusion of the vertebrae [1]. - While ultimately a feature of ankylosing spondylitis, it describes the overall appearance due to multiple **syndesmophytes**, rather than being a specific individual finding itself [1].

Q: A 35-year-old man presents with chronic sinusitis, hemoptysis, and renal dysfunction. Which of the following antibodies is most likely to be positive?

c-ANCA. p-ANCA (MPO) can be seen in some vasculitides [1], but the combination of **chronic sinusitis**, **hemoptysis** (indicating pulmonary involvement), and **renal dysfunction** is highly suggestive of **Granulomatosis with Polyangiitis (GPA)**. **c-ANCA** (cytoplasmic antineutrophil cytoplasmic antibodies), particularly those targeting **proteinase 3 (PR3)**, are the serological hallmark of GPA [1]. *Anti-dsDNA* - **Anti-dsDNA antibodies** are highly specific for **Systemic Lupus Erythematosus (SLE)** [1]. - While SLE can cause renal dysfunction and sometimes pulmonary symptoms, chronic sinusitis is not a typical hallmark, and the overall clinical picture does not align well with SLE. *Anti-Ro* - **Anti-Ro antibodies** are associated with **Sjogren's Syndrome** and sometimes SLE, especially in cases with subacute cutaneous lupus or neonatal lupus [1]. - Sjogren's syndrome primarily involves sicca symptoms (dry eyes, dry mouth) and would not typically present with the described triad of sinusitis, hemoptysis, and renal failure [1]. *Anti-centromere* - **Anti-centromere antibodies** are characteristic of the **limited cutaneous systemic sclerosis (CREST syndrome)** [1]. - This syndrome primarily involves Raynaud's phenomenon, telangiectasias, and calcinosis, and does not typically present with the given combination of symptoms.

Q: 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?

Selective IgA deficiency. ***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].

Q: 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?

Initiate anti-TNF therapy. ***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.

Q: 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?

Anti-Smith antibody. ***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.

Q: 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?

Behcet's disease. ***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.

Q: 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?

Pseudogout. ### 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.

Q: A 40-year-old female presents with a chronic dry cough and progressive dyspnea. A CT scan shows diffuse interstitial infiltrates, and pulmonary function tests indicate a restrictive pattern. Serology is positive for anti-SSA/Ro antibodies. What is the most likely diagnosis?

Sjögren's syndrome. ***Sjögren's syndrome*** - The presentation of **diffuse interstitial infiltrates** and **restrictive pulmonary function tests**, along with a **positive anti-SSA/Ro antibody**, strongly suggests Sjögren's syndrome, which can affect the lungs [1]. - While commonly associated with sicca symptoms (**dry eyes** and **mouth**), Sjögren's can also manifest as significant **extraglandular involvement**, including interstitial lung disease [2]. *Systemic sclerosis* - Although systemic sclerosis can cause **interstitial lung disease** and restrictive lung patterns, the primary serological marker in this case is **anti-SSA/Ro**, which is not typical for systemic sclerosis [2]. - Characteristic findings for systemic sclerosis usually include skin thickening and specific antibodies like **anti-Scl-70** or **anti-centromere antibodies**. [2] *Rheumatoid arthritis* - **Rheumatoid arthritis** can cause interstitial lung disease, but a positive **anti-SSA/Ro antibody** is not a primary diagnostic marker for RA; **rheumatoid factor** and **anti-CCP antibodies** are more characteristic [2]. - While RA can present with cough and dyspnea stemming from lung involvement, the serological profile points elsewhere. *Systemic lupus erythematosus* - While **anti-SSA/Ro antibodies** can be positive in **Systemic Lupus Erythematosus (SLE)**, the primary manifestation often involves other organ systems like kidneys, joints, and skin, with lung involvement being variable [2]. - Although SLE can cause pleurisy or lupus pneumonitis, **diffuse interstitial infiltrates** leading to restrictive patterns, combined with anti-SSA/Ro positivity, are more classically associated with Sjögren's syndrome as a **primary manifestation**.

Q: A 35-year-old female with heliotrope rash and Gottron's papules has a muscle biopsy showing inflammatory myopathy. What is the diagnosis?

Dermatomyositis. ***Dermatomyositis*** - The combination of a **heliotrope rash**, **Gottron's papules**, and **inflammatory myopathy** on muscle biopsy is pathognomonic for dermatomyositis [1], [2]. - This condition is characterized by **proximal muscle weakness** and distinctive dermatological manifestations [1], [2]. *Systemic lupus erythematosus (SLE)* - While SLE can cause a rash and myositis, the specific presentation of a **heliotrope rash** and **Gottron's papules** is not characteristic of SLE [2]. - SLE rashes typically include a **malar rash** or discoid lesions, and myositis is less common and usually milder [3]. *Polymyositis* - Polymyositis also presents with **inflammatory myopathy** and proximal muscle weakness, but it lacks the characteristic dermatological features seen in this patient [1]. - It does not involve **heliotrope rash** or **Gottron's papules** [1]. *Systemic sclerosis (SSc)* - SSc primarily affects the **skin** with thickening and hardening, and can involve internal organs, but does not typically present with the specific rash and papules described. - Muscle involvement in SSc is usually secondary to **fibrosis** or vasculopathy, distinct from the inflammatory myopathy of dermatomyositis.

Question 1

A 40-year-old woman with newly diagnosed lupus presents with proteinuria. Which antibody test is the most specific for lupus nephritis?

Accepted Answer

Anti-dsDNA

Answer

ANA

Answer

Anti-Ro

Answer

Anti-Smith

Question 2

In a patient with a history of chronic back pain and morning stiffness that improves with exercise, which radiographic finding is characteristic of ankylosing spondylitis?

Accepted Answer

Syndesmophytes

Answer

Bamboo spine

Answer

Osteophytes (associated with osteoarthritis)

Answer

Schmorl's nodes (indicate disc herniation)

Question 3

A 35-year-old man presents with chronic sinusitis, hemoptysis, and renal dysfunction. Which of the following antibodies is most likely to be positive?

Accepted Answer

c-ANCA

Answer

Anti-dsDNA

Answer

Anti-Ro

Answer

Anti-centromere

Question 4

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?

Accepted Answer

Selective IgA deficiency

Answer

Common variable immunodeficiency

Answer

Hyper-IgM syndrome

Answer

Severe combined immunodeficiency

Question 5

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?

Accepted Answer

Initiate anti-TNF therapy

Answer

Increase dose of NSAIDs

Answer

Begin physical therapy

Answer

Add methotrexate

Question 6

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?

Accepted Answer

Anti-Smith antibody

Answer

Rheumatoid factor

Answer

Antinuclear antibody (ANA) test

Answer

Anti-cyclic citrullinated peptide antibody

Question 7

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?

Accepted Answer

Behcet's disease

Answer

Systemic lupus erythematosus

Answer

Rheumatoid arthritis

Answer

Psoriatic arthritis

Question 8

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?

Accepted Answer

Pseudogout

Answer

Gout

Answer

Septic arthritis

Answer

Rheumatoid arthritis

Question 9

A 40-year-old female presents with a chronic dry cough and progressive dyspnea. A CT scan shows diffuse interstitial infiltrates, and pulmonary function tests indicate a restrictive pattern. Serology is positive for anti-SSA/Ro antibodies. What is the most likely diagnosis?

Accepted Answer

Sjögren's syndrome

Answer

Systemic sclerosis

Answer

Rheumatoid arthritis

Answer

Systemic lupus erythematosus

Question 10

A 35-year-old female with heliotrope rash and Gottron's papules has a muscle biopsy showing inflammatory myopathy. What is the diagnosis?

Accepted Answer

Dermatomyositis

Answer

Systemic lupus erythematosus (SLE)

Answer

Polymyositis

Answer

Systemic sclerosis (SSc)

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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