Rheumatology and Immunology Practice Questions

Q: Which organism most commonly causes reactive arthritis?

Chlamydia. **Explanation:** **Reactive Arthritis (ReA)** is a sterile joint inflammation that develops following a distant infection, typically of the gastrointestinal (GI) or urogenital (UG) tract. It belongs to the group of **Seronegative Spondyloarthropathies** [1]. **Why Chlamydia is correct:** **Chlamydia trachomatis** is the most common cause of reactive arthritis worldwide. It typically follows a urogenital infection (often asymptomatic in women) [1]. It is the classic trigger for the "Reiter’s Syndrome" triad: **Urethritis, Conjunctivitis, and Arthritis** ("Can't see, can't pee, can't climb a tree") [1]. **Analysis of Incorrect Options:** * **Ureaplasma urealyticum:** While it is a known urogenital trigger for ReA, it is significantly less common than *Chlamydia*. * **Group A beta-hemolytic streptococci:** This organism causes **Acute Rheumatic Fever (ARF)**. While "Post-streococcal reactive arthritis" exists as a distinct entity, it is not the "most common" cause of classic ReA. * **Borrelia burgdorferi:** This is the causative agent of **Lyme Disease**. While it causes chronic inflammatory arthritis, it is categorized as an infectious arthritis (Lyme arthritis) rather than a sterile reactive arthritis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Common Triggers:** * **Urogenital:** *Chlamydia trachomatis* (Most common overall) [1]. * **Enteric (GI):** *Shigella flexneri*, *Salmonella*, *Campylobacter*, and *Yersinia* [1]. 2. **Genetic Association:** Strongly associated with **HLA-B27** (present in 30–50% of cases) [1]. 3. **Dermatological Findings:** Look for **Keratoderma blennorrhagicum** (vesicular/pustular lesions on palms/soles) and **Circinate balanitis** [1]. 4. **Joint Involvement:** Typically an **asymmetric oligoarthritis** affecting large joints of the lower extremities (knees, ankles) [1].

Q: An elderly patient presents with severe temporal headache, jaw claudication, and scalp tenderness. ESR is markedly elevated. What is the most likely diagnosis?

Giant cell arteritis. ***Giant cell arteritis*** - The combination of **temporal headache**, **jaw claudication**, **scalp tenderness** in an elderly patient with **markedly elevated ESR** is pathognomonic for giant cell arteritis. - **Temporal artery biopsy** showing transmural inflammation with giant cells confirms the diagnosis and prevents irreversible **vision loss**. *Wegener's granulomatosis* - Primarily affects the **respiratory tract** and **kidneys** with necrotizing granulomatous inflammation, not temporal arteries. - Presents with **sinusitis**, **pulmonary nodules**, and **glomerulonephritis**, with positive **c-ANCA/PR3** antibodies. *Microscopic polyangiitis* - A **small vessel ANCA-associated vasculitis** affecting capillaries and venules, not large arteries like the temporal artery. - Typically presents with **pulmonary-renal syndrome** and positive **p-ANCA/MPO** antibodies, without jaw claudication. *Takayasu arteritis* - Affects **young women** under 40 years old, involving the **aortic arch** and its major branches. - Presents with **arm claudication**, **blood pressure discrepancies**, and **bruits**, not temporal symptoms in elderly patients.

Q: Under the Jones criteria, which one of the following is a major criterion for the diagnosis of acute rheumatic fever?

Carditis. **Explanation:** Acute Rheumatic Fever (ARF) is an autoimmune multi-systemic response following a Group A Streptococcal (GAS) pharyngeal infection. Diagnosis is based on the **Revised Jones Criteria (2015)**, which categorizes findings into Major and Minor criteria based on the patient's risk population (Low vs. Moderate/High risk). **Why Carditis is correct:** **Carditis** is a **Major criterion** across all risk groups. It typically presents as a pancarditis (endocarditis, myocarditis, and pericarditis). In the revised criteria, carditis can be either **clinical** (murmurs of mitral or aortic regurgitation) or **subclinical** (detected via echocardiographic evidence of valvulitis), even if a murmur is absent. **Analysis of Incorrect Options:** * **A. Elevated acute-phase reactants (ESR/CRP):** These are **Minor criteria**. They indicate systemic inflammation but are non-specific to ARF. * **B. Elevated ASO titer:** This is not a Jones criterion itself; rather, it is the **required evidence of a preceding GAS infection**. Diagnosis of ARF requires meeting Jones criteria *plus* evidence of infection (except in cases of chorea or indolent carditis). * **C. Increased PR interval:** This is a **Minor criterion**. It represents a first-degree AV block and must be interpreted carefully if carditis is already used as a major criterion. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for Major Criteria (JONES):** **J**oints (Migratory Polyarthritis), **O** (Carditis - looks like a heart), **N**odules (Subcutaneous), **E**rythema marginatum, **S**ydenham chorea. 2. **Joints:** In high-risk populations, *Monoarthritis* or *Polyarthralgia* can now be considered Major criteria. 3. **Most common valve affected:** Mitral valve (Mitral Regurgitation is the most common early finding). 4. **Pathognomonic finding:** **Aschoff bodies** (granulomas with Anitschkow "caterpillar" cells) seen on myocardial histology.

Q: Anti U1-RNP antibody is seen in which condition?

Mixed Connective Tissue Disease (MCTD). ### Explanation **Correct Answer: C. Mixed Connective Tissue Disease (MCTD)** **1. Why MCTD is the correct answer:** Mixed Connective Tissue Disease (MCTD) is a distinct overlap syndrome characterized by clinical features of SLE, Systemic Sclerosis, and Polymyositis [2]. The **hallmark serological marker** for MCTD is the presence of high titers of **Anti-U1 ribonucleoprotein (U1-RNP) antibodies** [1], [2]. In fact, according to the Kasukawa or Alarcón-Segovia diagnostic criteria, a high titer of Anti-U1 RNP is a **mandatory requirement** for the diagnosis of MCTD. **2. Why other options are incorrect:** * **A. SLE:** While Anti-U1 RNP can be seen in about 30-40% of SLE patients, it is not specific. The highly specific markers for SLE are **Anti-dsDNA** and **Anti-Smith (Sm)** antibodies [1], [3]. * **B. Scleroderma:** The characteristic antibodies are **Anti-Scl-70 (Anti-topoisomerase I)** for diffuse cutaneous systemic sclerosis and **Anti-centromere** for limited cutaneous systemic sclerosis (CREST syndrome). * **C. Dermatomyositis:** The most specific marker is **Anti-Mi-2** antibody. Other myositis-specific antibodies include **Anti-Jo-1** (associated with Antisynthetase syndrome). **3. High-Yield Clinical Pearls for NEET-PG:** * **MCTD Clinical Triad:** Raynaud’s phenomenon, "Puffy hands" (swollen fingers), and Myositis/Arthralgia [2]. * **Prognosis:** The most common cause of death in MCTD is **Pulmonary Hypertension** [2]. * **Serology Tip:** If a question mentions "Anti-RNP" without the "U1" prefix, it still refers to MCTD. However, if **Anti-Smith** is present, the diagnosis shifts toward SLE, as Anti-Smith is rarely positive in pure MCTD [1]. * **ANA Pattern:** Anti-U1 RNP typically produces a **speckled pattern** on Immunofluorescence.

Q: What crystals are aspirated from the bursa of an elbow in a patient with rheumatoid arthritis?

Cholesterol. ### Explanation **Correct Option: A. Cholesterol** In patients with chronic inflammatory conditions like **Rheumatoid Arthritis (RA)**, cholesterol crystals can occasionally be found in the synovial fluid or bursal aspirates (especially the olecranon bursa) [1]. These crystals form due to the chronic breakdown of cell membranes and local tissue destruction within the joint or bursa, leading to an accumulation of lipids that crystallize over time. Under polarized light, they typically appear as **large, notched, square or rectangular plates** with "broken corners." **Why other options are incorrect:** * **B. Calcium apatite:** These are associated with calcific tendonitis or Milwaukee shoulder. They are extremely small and usually require electron microscopy or Alizarin Red staining for visualization. * **C. Calcium oxalate:** These are typically seen in the joints of patients with **End-Stage Renal Disease (ESRD)** undergoing long-term hemodialysis [1]. They appear as envelope-shaped crystals. * **D. Calcium pyrophosphate dihydrate (CPPD):** These are the hallmark of **Pseudogout** [1]. They are rhomboid-shaped and show weak positive birefringence. While RA patients can have co-existing CPPD, cholesterol crystals are the classic association for chronic rheumatoid bursal effusions. **High-Yield Clinical Pearls for NEET-PG:** * **Cholesterol Crystals:** Associated with "chronic" effusions (RA, Osteoarthritis) [1]. They have a characteristic **"notched corner"** appearance. * **Monosodium Urate (MSU):** Needle-shaped, strongly negative birefringent (Gout) [1]. * **CPPD:** Rhomboid-shaped, weakly positive birefringent (Pseudogout). * **Rheumatoid Factor (RF):** Though common in RA, it is not specific; however, high titers often correlate with extra-articular manifestations like rheumatoid nodules and bursitis.

Question 1

Which organism most commonly causes reactive arthritis?

Accepted Answer

Chlamydia

Answer

Ureaplasma urealyticum

Answer

Group A beta hemolytic streptococci

Answer

Borrelia burgdorferi

Question 2

An elderly patient presents with severe temporal headache, jaw claudication, and scalp tenderness. ESR is markedly elevated. What is the most likely diagnosis?

Accepted Answer

Giant cell arteritis

Answer

Wegener's granulomatosis

Answer

Microscopic polyangiitis

Answer

Takayasu arteritis

Question 3

Which of the following statements are true about Dermatomyositis?

Accepted Answer

All cases are associated with internal malignancy

Answer

Gottron sign

Answer

ANA is positive in all cases

Answer

Proximal muscle wasting

Question 4

A 48-year-old man presents with macules, papules, ulcers, and eschars on his extremities, hands, genitals, and face, as well as nasal and oral mucosae. The rash is accompanied by severe malaise, fever, arthralgia, paresthesia, and microhematuria. Cryoglobulins and high titers of circulating immune complexes were noted. Steroid treatment and plasmapheresis were instituted with good results. This clinical presentation is most likely secondary to which of the following conditions?

Accepted Answer

Vasculitic ulcer

Answer

Aerial ulcer

Answer

Venous ulcer

Answer

Neurotrophic ulcer

Question 5

Under the Jones criteria, which one of the following is a major criterion for the diagnosis of acute rheumatic fever?

Accepted Answer

Carditis

Answer

Elevated acute-phase reactants

Answer

Elevated ASO titer

Answer

Increased PR interval

Question 6

Anti U1-RNP antibody is seen in which condition?

Accepted Answer

Mixed Connective Tissue Disease (MCTD)

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Scleroderma

Answer

Dermatomyositis

Question 7

What crystals are aspirated from the bursa of an elbow in a patient with rheumatoid arthritis?

Accepted Answer

Cholesterol

Answer

Calcium apatite

Answer

Calcium oxalate

Answer

Calcium pyrophosphate dihydrate

Question 8

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 9

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 10

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

Rheumatology and Immunology — MCQs

Rheumatology and Immunology — MCQs

On this page

Practice by Chapter

Want unlimited practice?