Rheumatology and Immunology Practice Questions

Q: 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?

Polymyositis. ***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.

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 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: 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?

Scleroderma. ***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.

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 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 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 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 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.

Question 1

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?

Accepted Answer

Polymyositis

Answer

Dermatomyositis

Answer

Inclusion body myositis

Answer

Rhabdomyolysis

Question 2

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 3

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 4

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?

Accepted Answer

Scleroderma

Answer

Systemic lupus erythematosus

Answer

Dermatomyositis

Answer

Sarcoidosis

Question 5

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 6

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 7

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 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 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 10

A 45-year-old patient presents with skin thickening, Raynaud's phenomenon, and digital ulcers. Which enzyme is the target of autoantibodies in this autoimmune disorder?

Accepted Answer

Histone deacetylase

Answer

DNA polymerase

Answer

Protein kinase

Answer

RNA polymerase II

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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