Rheumatology and Immunology Practice Questions

Q: What is the most effective method to differentiate septic arthritis from inflammatory arthritis in a patient with a swollen, painful knee and high white blood cell count in synovial fluid?

Joint fluid cell count and Gram stain. ### Joint fluid cell count and Gram stain - A **Gram stain** of synovial fluid is crucial for identifying bacterial organisms, directly indicating **septic arthritis**. [1] - A very **high cell count** (often >50,000 cells/mm³) with a predominance of **neutrophils** is highly suggestive of septic arthritis, distinguishing it from most inflammatory arthritides. [1] *Joint fluid culture and uric acid levels* - While **joint fluid culture** is essential for definitive diagnosis of septic arthritis, its results are not immediately available, making it less effective for initial differentiation compared to Gram stain for rapid management decisions. [2] - **Uric acid levels** in synovial fluid are primarily used to diagnose **gouty arthritis** (a form of inflammatory arthritis) but do not directly differentiate between septic and other inflammatory causes. *Joint fluid culture and synovial biopsy* - **Synovial biopsy** is generally reserved for cases where other diagnostic methods are inconclusive, such as atypical infections or chronic inflammatory conditions, and is not a first-line diagnostic tool for acute differentiation. [1] - As mentioned, **joint fluid cultures** provide definitive identification but take time, delaying immediate differentiation. [3] *Rheumatoid factor and synovial biopsy* - **Rheumatoid factor (RF)** is a serological marker for **rheumatoid arthritis** (an inflammatory arthritis) and does not directly help differentiate between septic arthritis and other inflammatory conditions in the acute setting of a swollen joint. - **Synovial biopsy**, as explained, is a more invasive and time-consuming procedure not typically used for initial acute differentiation. [1]

Q: In a patient with suspected rheumatoid arthritis, which antibody is the most specific for diagnosis?

Anti-CCP antibody. ***Anti-CCP antibody*** - **Anti-CCP antibodies** (antibodies to cyclic citrullinated peptides) are highly specific for **rheumatoid arthritis (RA)**, with a specificity of around 90-98%. - Their presence can confirm RA diagnosis, especially in **seronegative** cases for rheumatoid factor, and is also predictive of more aggressive disease. *Rheumatoid factor* - **Rheumatoid factor (RF)** is often positive in RA patients but is less specific as it can be found in other autoimmune diseases, infections, and even in healthy individuals, especially the elderly. - While sensitive for RA, its lower specificity means it cannot exclusively distinguish RA from other conditions [2]. *ANA* - **Antinuclear antibodies (ANA)** are a hallmark of **systemic lupus erythematosus (SLE)** and other autoimmune diseases like Sjögren's syndrome or scleroderma [1]. - While sometimes positive in RA, ANA is not specific enough to diagnose RA and primarily suggests a broader autoimmune process [1]. *Anti-dsDNA antibody* - **Anti-dsDNA antibodies** are highly specific for **systemic lupus erythematosus (SLE)** and are rarely seen in other conditions, making them a key marker for SLE diagnosis and monitoring. - They are not considered a diagnostic marker for rheumatoid arthritis.

Q: A 60-year-old man presents with dry eyes and dry mouth. A biopsy of the minor salivary glands shows lymphocytic infiltration. What is the most likely diagnosis?

Sjogren's syndrome. ***Sjogren's syndrome*** - The classic presentation of **dry eyes (xerophthalmia)** and **dry mouth (xerostomia)**, coupled with **lymphocytic infiltration** of minor salivary glands, is highly indicative of Sjogren's syndrome. - This condition is a **chronic autoimmune** disorder primarily affecting exocrine glands. *Rheumatoid arthritis* - While rheumatoid arthritis is an autoimmune condition, its primary manifestations involve **synovitis** of peripheral joints, causing pain, swelling, and stiffness, with systemic dryness being less common as a primary presenting symptom. - Lymphocytic infiltration of salivary glands is not a diagnostic feature of RA. *Systemic lupus erythematosus* - SLE is a multi-system autoimmune disease characterized by a wide range of symptoms including **malaria rash**, **arthritis**, **serositis**, and **renal involvement**. - Although dry eyes and mouth can occur in SLE (secondary Sjogren's), the biopsy finding of predominant lymphocytic infiltration of salivary glands points directly to Sjogren's syndrome as the primary diagnosis. *Sarcoidosis* - Sarcoidosis is a multisystem **granulomatous disease** characterized by non-caseating granulomas in affected organs. - While it can manifest with salivary gland enlargement and sicca symptoms, a biopsy would typically show **granulomatous inflammation** rather than just lymphocytic infiltration.

Q: A 30-year-old male with a history of ankylosing spondylitis presents with severe back pain and restricted chest expansion. What is the most appropriate next step in management?

Biologic therapy targeting TNF-alpha. Biologic therapy targeting TNF-alpha - For patients with active ankylosing spondylitis (AS) with **severe symptoms** and restricted chest expansion despite conventional treatment, **TNF-alpha inhibitors** are highly effective in reducing inflammation and improving function [1]. - This therapy helps to slow disease progression and prevent further structural damage by blocking the **pro-inflammatory cytokine TNF-alpha**. *Long-term NSAID therapy* - While **NSAIDs** are the first-line treatment for pain and stiffness in AS, they may not be sufficient for severe disease or patients with inadequate response. - They primarily manage symptoms and do not typically halt **disease progression** in severe cases. *Disease-modifying antirheumatic drugs (DMARDs)* - Traditional **DMARDs** like methotrexate or sulfasalazine are generally less effective for axial symptoms of AS compared to TNF-alpha inhibitors. - Their primary role is often in treating **peripheral arthritis** associated with AS. *Rehabilitation exercises only* - **Rehabilitation exercises** are crucial for maintaining mobility and posture in AS but are insufficient as a standalone treatment for severe inflammation and restricted chest expansion. - While important for functional outcomes, they cannot address the underlying **inflammatory process** in severe disease.

Q: A 50-year-old man presents with skin thickening, Raynaud's phenomenon, and gastroesophageal reflux disease (GERD). Laboratory results show positive autoantibodies associated with connective tissue diseases. What is the likely diagnosis?

Scleroderma (systemic sclerosis). ***Scleroderma*** - The combination of **skin thickening**, **Raynaud's phenomenon**, and **positive anti-Scl-70 antibodies** is characteristic of scleroderma, particularly diffuse scleroderma [1]. - Associated gastrointestinal symptoms like **gastroesophageal reflux disease (GERD)** are common in scleroderma due to esophageal motility issues [1]. *Systemic lupus erythematosus* - SLE typically presents with a **butterfly rash**, **joint symptoms**, and diverse systemic involvement, none of which are primary features here. - The presence of **anti-Scl-70 antibodies** is not characteristic of SLE but rather specific for scleroderma. *Dermatomyositis* - Characterized by **muscle weakness** and **skin rashes** (heliotrope rash), which are absent in this scenario. - Usually linked with **anti-Jo-1 antibodies**, making it distinct from the findings here. *Sjogren syndrome* - Primarily presents with **dry eyes** and **dry mouth**, and typically lacks significant skin changes or Raynaud's phenomenon. - Autoantibodies like **anti-Ro (SSA)** are more commonly seen in Sjogren syndrome rather than anti-Scl-70.

Q: A patient presents with Raynaud's phenomenon and diffuse skin thickening. Antibody testing reveals anti-Scl-70 antibodies. What is the most likely diagnosis?

Systemic sclerosis. Systemic sclerosis - The combination of **Raynaud's phenomenon**, **diffuse skin thickening**, and the presence of **anti-Scl-70 antibodies** is highly characteristic of diffuse cutaneous systemic sclerosis. T lymphocytes infiltrate the skin and there is abnormal fibroblast activation, resulting in symmetrical thickening and tightening of the skin [1]. - **Anti-Scl-70 antibodies** (also known as **anti-topoisomerase I**) are a specific marker for systemic sclerosis, particularly the diffuse form, and are associated with a higher risk of **interstitial lung disease** and **scleroderma renal crisis**. *Systemic lupus erythematosus* - While **Raynaud's phenomenon** can occur in SLE, **diffuse skin thickening** as described is not a primary feature; skin manifestations in SLE include **malar rash**, **discoid rash**, and **photosensitivity**. Patients with active SLE almost always test positive for ANA [2]. - **Anti-Scl-70 antibodies** are not typically found in SLE; hallmark antibodies for SLE include **anti-dsDNA** and **anti-Sm antibodies** [2]. *Dermatomyositis* - Characterized by **proximal muscle weakness** and distinctive skin rashes like **Gottron's papules** and the **heliotrope rash**, not diffuse skin thickening. - Associated autoantibodies include **anti-Jo-1**, **anti-MDA5**, and **anti-TIF1γ**, not anti-Scl-70. *Rheumatoid arthritis* - Primarily affects the **synovial joints**, causing symmetrical polyarthritis, and does not typically involve significant skin thickening or Raynaud's phenomenon as a dominant feature [3]. - Associated with **rheumatoid factor (RF)** and **anti-cyclic citrullinated peptide (anti-CCP) antibodies**, not anti-Scl-70.

Q: A 28-year-old woman presents with fever, weight loss, and night sweats. She has a history of painful oral and genital ulcers. Which test is most likely to confirm the diagnosis?

Pathergy test. ***Pathergy test*** - The Pathergy test is a characteristic, although not universally positive, **skin hypersensitivity reaction** seen in Behçet's disease, which is highly suggested by the patient's presentation of recurrent oral and genital ulcers, along with systemic symptoms like fever, weight loss, and night sweats [1]. - A **positive Pathergy test** involves the development of a papule or pustule 24-48 hours after an oblique skin prick with a sterile needle, reflecting a nonspecific hyperreactivity of the skin. *HLA-B27* - **HLA-B27** is primarily associated with **spondyloarthropathies** such as ankylosing spondylitis, reactive arthritis, and psoriatic arthritis, which do not typically present with painful oral and genital ulcers. - Its presence would not specifically confirm a diagnosis of Behçet's disease, which has a distinct clinical presentation. *ANA* - **Antinuclear antibodies (ANA)** are a hallmark of **systemic lupus erythematosus (SLE)** and other autoimmune connective tissue diseases [2]. - While SLE can cause oral ulcers, genital ulcers are less common, and the overall clinical picture with fever, weight loss, and night sweats, along with recurrent oral and genital ulcers, is more indicative of Behçet's disease than SLE. *Anti-dsDNA* - **Anti-double-stranded DNA (anti-dsDNA)** antibodies are highly specific for **systemic lupus erythematosus (SLE)** and are often associated with lupus nephritis [3]. - While SLE can cause fever and weight loss, and rarely oral ulcers, the classic triad of recurrent oral and genital ulcers along with systemic symptoms strongly points away from SLE and towards Behçet's disease.

Q: A 50-year-old male presents with chronic back pain and a progressive stooped posture. X-rays reveal vertebral squaring and syndesmophytes. What is the most likely diagnosis?

Ankylosing Spondylitis. ***Ankylosing Spondylitis*** - **Ankylosing spondylitis** is characterized by chronic back pain and progressive spinal stiffness, leading to a **stooped posture** [1]. - **Vertebral squaring** (loss of the normal anterior concavity of vertebral bodies) and **syndesmophytes** (bony growths forming between vertebrae) are classic radiographic findings [1], [2]. *Osteoarthritis* - **Osteoarthritis** typically involves mechanical pain that worsens with activity and improves with rest, often in weight-bearing joints [3]. - Radiographic findings include **osteophytes**, **joint space narrowing**, and **subchondral sclerosis**, rather than vertebral squaring and syndesmophytes. *Rheumatoid arthritis* - **Rheumatoid arthritis** primarily affects peripheral joints symmetrically, leading to inflammation and destruction; it rarely affects the axial spine significantly, other than the C1-C2 joint. - It is associated with **morning stiffness** lasting over 30 minutes and a positive **rheumatoid factor** or **anti-CCP antibodies**. *Degenerative disc disease* - **Degenerative disc disease** involves alterations in the intervertebral discs, leading to back pain, but typically does not cause vertebral squaring or syndesmophytes. - Radiographic features often include **disc space narrowing** and vacuum phenomenon, without the characteristic bony bridging seen in ankylosing spondylitis [1].

Q: A 33-year-old man presents with an erythematous rash on his cheeks and nose that worsens with sun exposure. What is the most likely diagnosis?

Systemic lupus erythematosus. ***Systemic lupus erythematosus*** - The presentation of an **erythematous rash** on the cheeks and nose that **worsens with sun exposure** is highly characteristic of the **malar rash** commonly seen in systemic lupus erythematosus (SLE) [1]. - SLE is an **autoimmune disease** with diverse manifestations, and photosensitivity is a common feature [1], [2]. *Psoriasis* - Characterized by **well-demarcated, silvery scales** on erythematous plaques, typically on extensor surfaces, the scalp, and nails. - While sun exposure can sometimes trigger or alleviate psoriasis, the described rash (malar distribution, photosensitivity) is not typical. *Seborrheic dermatitis* - Causes a **greasy, scaly rash** predominantly in areas rich in sebaceous glands, such as the scalp, eyebrows, and nasolabial folds. - It does not typically present as a photosensitive malar rash. *Rosacea* - Characterized by **facial erythema**, **telangiectasias**, papules, and pustules, often affecting the cheeks, nose, and forehead [2]. - While rosacea can be worsened by sun exposure, the described rash (often butterfly-shaped) and its strong association with photosensitivity in this context are more indicative of SLE.

Q: A 30-year-old female with a new diagnosis of systemic lupus erythematosus (SLE) presents with fatigue and joint pain. Which medication is most likely to alleviate her symptoms?

Hydroxychloroquine. ***Hydroxychloroquine*** - This is the **first-line treatment** for most patients with SLE, especially for managing fatigue, joint pain, skin rashes, and serositis. - It has a good safety profile for long-term use and helps prevent **SLE flares** and reduce major organ damage. *Methotrexate* - This is a **disease-modifying antirheumatic drug (DMARD)** often used in SLE for severe arthritis or skin involvement, but it is not typically the initial choice for general fatigue and joint pain. - It requires close monitoring for **hepatic toxicity**, bone marrow suppression, and is contraindicated in pregnancy. *Cyclosporine* - This is an **immunosuppressant** reserved for more severe manifestations of SLE, such as **lupus nephritis** or refractory cases when other therapies have failed. - Its use is limited by potential adverse effects like **nephrotoxicity** and hypertension. *Prednisone* - This is a **corticosteroid** often used for acute flares or more severe manifestations of SLE due to its rapid anti-inflammatory and immunosuppressive effects. - However, it's generally not ideal for long-term, chronic management of mild to moderate symptoms like fatigue and joint pain due to significant **side effects** with prolonged use.

Question 1

What is the most effective method to differentiate septic arthritis from inflammatory arthritis in a patient with a swollen, painful knee and high white blood cell count in synovial fluid?

Accepted Answer

Joint fluid cell count and Gram stain

Answer

Joint fluid culture and uric acid levels

Answer

Rheumatoid factor and synovial biopsy

Answer

Joint fluid culture and synovial biopsy

Question 2

In a patient with suspected rheumatoid arthritis, which antibody is the most specific for diagnosis?

Accepted Answer

Anti-CCP antibody

Answer

Rheumatoid factor

Answer

ANA

Answer

Anti-dsDNA antibody

Question 3

A 60-year-old man presents with dry eyes and dry mouth. A biopsy of the minor salivary glands shows lymphocytic infiltration. What is the most likely diagnosis?

Accepted Answer

Sjogren's syndrome

Answer

Rheumatoid arthritis

Answer

Systemic lupus erythematosus

Answer

Sarcoidosis

Question 4

A 30-year-old male with a history of ankylosing spondylitis presents with severe back pain and restricted chest expansion. What is the most appropriate next step in management?

Accepted Answer

Biologic therapy targeting TNF-alpha

Answer

Long-term NSAID therapy

Answer

Disease-modifying antirheumatic drugs (DMARDs)

Answer

Rehabilitation exercises only

Question 5

A 50-year-old man presents with skin thickening, Raynaud's phenomenon, and gastroesophageal reflux disease (GERD). Laboratory results show positive autoantibodies associated with connective tissue diseases. What is the likely diagnosis?

Accepted Answer

Scleroderma (systemic sclerosis)

Answer

Dermatomyositis (inflammatory myopathy)

Answer

Sjogren's syndrome (autoimmune condition)

Answer

Systemic lupus erythematosus (SLE)

Question 6

A patient presents with Raynaud's phenomenon and diffuse skin thickening. Antibody testing reveals anti-Scl-70 antibodies. What is the most likely diagnosis?

Accepted Answer

Systemic sclerosis

Answer

Systemic lupus erythematosus

Answer

Dermatomyositis

Answer

Rheumatoid arthritis

Question 7

A 28-year-old woman presents with fever, weight loss, and night sweats. She has a history of painful oral and genital ulcers. Which test is most likely to confirm the diagnosis?

Accepted Answer

Pathergy test

Answer

HLA-B27

Answer

ANA

Answer

Anti-dsDNA

Question 8

A 50-year-old male presents with chronic back pain and a progressive stooped posture. X-rays reveal vertebral squaring and syndesmophytes. What is the most likely diagnosis?

Accepted Answer

Ankylosing Spondylitis

Answer

Osteoarthritis

Answer

Rheumatoid arthritis

Answer

Degenerative disc disease

Question 9

A 33-year-old man presents with an erythematous rash on his cheeks and nose that worsens with sun exposure. What is the most likely diagnosis?

Accepted Answer

Systemic lupus erythematosus

Answer

Psoriasis

Answer

Seborrheic dermatitis

Answer

Rosacea

Question 10

A 30-year-old female with a new diagnosis of systemic lupus erythematosus (SLE) presents with fatigue and joint pain. Which medication is most likely to alleviate her symptoms?

Accepted Answer

Hydroxychloroquine

Answer

Methotrexate

Answer

Cyclosporine

Answer

Prednisone

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

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