Crystal Arthropathies — MCQs
All are true about gout except:
In a patient with gouty arthritis, strongly birefringent needle-shaped crystals with negative elongation in synovial fluid aspiration are composed of:
In a patient with gouty arthritis, synovial fluid aspiration will show:
A skin biopsy shows 'snowstorm' appearance on polarized microscopy. Which histological finding would best confirm gouty tophi?
Which of the following is the best investigation for acute gout?
Diagnosis of Gout is confirmed by which test?
In a patient with gouty arthritis, synovial fluid aspiration will show which of the following:
A 58-year-old man with a diagnosis of chronic myeloid leukemia is treated with intensive chemotherapy. He goes into remission but develops pain in the left wrist. On physical examination, there is swelling and warmth on the palpation of the wrist. Polarized light microscopy of fluid aspirated from the wrist joint shows needle-shaped crystals that display negative birefringence. Which of the following processes most likely played an important role in the pathogenesis of the patient's wrist pain?
45-year-old man presented to outpatient department with hot, swollen left big toe and a painful lesion on the rim of his left pinna. Polarized light microscopy of the synovial fluid shows dense neutrophilic infiltrate and crystals that are negatively birefringent. Patient is likely to be suffering from?
Which of these is characteristic of gout?
Crystal Arthropathies Indian Medical PG Practice Questions and MCQs
Question 1: All are true about gout except:
- A. Is caused by purine metabolism disorder
- B. Causes tophi in the extraocular muscle tendon
- C. Causes podagra
- D. Is directly related to alcohol consumption (Correct Answer)
Explanation: *** Is directly related to alcohol consumption*** - While **alcohol consumption**, particularly beer and spirits, is a **risk factor** for gout flares by increasing uric acid production and inhibiting its excretion, it is not the direct cause of the underlying **purine metabolism disorder**. [1], [2] - Gout is primarily caused by **hyperuricemia**, which leads to the deposition of **monosodium urate crystals** in joints and tissues. [3], [4] *Is caused by purine metabolism disorder* - Gout is fundamentally caused by a **disorder of purine metabolism**, leading to either **overproduction of uric acid** or **underexcretion of uric acid** from the kidneys. [1], [2] - This imbalance results in elevated **serum uric acid levels** (hyperuricemia), which is a prerequisite for gout development. [1] *Causes tophi in the extraocular muscle tendon* - Gout can cause **tophi**, which are deposits of **monosodium urate crystals**, but they typically form in cooler peripheral areas like the **ear helix**, fingers, toes, and around joints. [4] - While rare, tophi can occur in unusual locations, deposition in **extraocular muscle tendons** is highly atypical and not a common manifestation of gout. *Causes podagra* - **Podagra** is a classic symptom of gout, referring specifically to acute inflammation and severe pain in the **first metatarsophalangeal joint** (big toe). [2] - It is one of the most common initial presentations of **gouty arthritis** and is highly characteristic of the disease. [2]
Question 2: In a patient with gouty arthritis, strongly birefringent needle-shaped crystals with negative elongation in synovial fluid aspiration are composed of:
- A. Homogentisic acid
- B. Calcium pyrophosphate
- C. Sodium pyrophosphate
- D. Monosodium urate (Correct Answer)
Explanation: ***Monosodium urate*** - **Monosodium urate (MSU)** crystals are characteristic of **gouty arthritis** [1]. They appear as **needle-shaped** crystals with **strong negative birefringence** when viewed under a polarized light microscope, which helps in differentiating them from other crystals. - These crystals typically precipitate in joints due to **hyperuricemia**, causing an acute inflammatory response [2]. *Homogentisic acid* - **Homogentisic acid** crystals are associated with **alkaptonuria (ochronosis)**, a rare metabolic disorder, not gout. - These crystals impart a dark color to cartilage and urine upon oxidation, and their microscopic appearance is distinct from MSU crystals. *Calcium pyrophosphate* - **Calcium pyrophosphate dihydrate (CPPD)** crystals are associated with **pseudogout**, a condition similar to gout but caused by different crystals [3]. - CPPD crystals appear as **rhomboid or rod-shaped** and exhibit **weakly positive birefringence**, differentiating them from MSU crystals. *Sodium pyrophosphate* - **Sodium pyrophosphate** is not a commonly recognized crystal type found in synovial fluid that causes inflammatory arthritis. - While pyrophosphate is involved in bone metabolism, its sodium salt does not typically form characteristic crystals in joints like MSU or CPPD.
Question 3: In a patient with gouty arthritis, synovial fluid aspiration will show:
- A. Calcium Pyrophosphate crystals
- B. Mononuclear Leucocytosis
- C. Polymorphonuclear Leukocytosis
- D. Monosodium Urate crystals (Correct Answer)
Explanation: ***Monosodium Urate crystals*** - The definitive diagnosis of **gouty arthritis** is made by identifying **needle-shaped, negatively birefringent monosodium urate crystals** in the synovial fluid [1]. - These crystals are formed from **elevated uric acid levels** and precipitate in joints, triggering acute inflammation [2]. *Calcium Pyrophosphate crystals* - These crystals are characteristic of **pseudogout**, or **calcium pyrophosphate deposition disease (CPPD)**, and are typically **rhomboid-shaped and positively birefringent** [3]. - While both gout and pseudogout cause acute arthritis, the **crystal morphology and birefringence** differentiate them [3]. *Mononuclear Leucocytosis* - **Mononuclear leucocytosis** in synovial fluid is more commonly seen in **chronic inflammatory conditions** or some **viral arthritides**, not typically in acute gout attacks. - Acute gout is characterized by a strong **neutrophilic inflammatory response** [1]. *Polymorphonuclear Leukocytosis* - While **polymorphonuclear leukocytosis** (predominantly neutrophils) is indeed seen in the synovial fluid of patients with acute gout due to the intense inflammatory response, it is a **non-specific finding** of inflammation [1]. - It does not definitively diagnose gout, as it can be present in other inflammatory arthritides, including **septic arthritis**, making the **crystal identification crucial**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1218-1220. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 682-683. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 683-684.
Question 4: A skin biopsy shows 'snowstorm' appearance on polarized microscopy. Which histological finding would best confirm gouty tophi?
- A. Rhomboid crystals
- B. Malta crosses
- C. Needle-shaped crystals (Correct Answer)
- D. Apple-green birefringence
Explanation: ***Needle-shaped crystals*** - The "snowstorm" appearance on polarized microscopy, combined with the presence of **needle-shaped crystals**, is highly characteristic of **monosodium urate (MSU) crystals** seen in gouty tophi [1]. - These crystals typically show **strong negative birefringence** under polarized light [1]. *Rhomboid crystals* - **Rhomboid crystals** are characteristic of **calcium pyrophosphate dihydrate (CPPD) crystal deposition disease**, also known as pseudogout. - These crystals exhibit **positive birefringence**, differentiating them from MSU crystals. *Malta crosses* - **"Malta crosses"** are spherical aggregates of crystals, most commonly seen in **lipid-rich conditions**, such as cholesterol crystals in synovial fluid or fat emboli. - While they show birefringence, their morphology and association are distinct from gout. *Apple-green birefringence* - **Apple-green birefringence** is a characteristic finding in tissues stained with **Congo red** when viewed under polarized light, indicating the presence of **amyloid deposits**. - Amyloidosis is a protein misfolding disorder, unrelated to the crystal deposition seen in gout. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1218-1220.
Question 5: Which of the following is the best investigation for acute gout?
- A. Uric acid in urine
- B. Anti CCP antibodies
- C. Serum uric acid
- D. Uric acid in synovial fluid (Correct Answer)
Explanation: ***Uric acid in synovial fluid*** - The definitive diagnosis of acute gout is established by identifying **negatively birefringent needle-shaped uric acid crystals** within the synovial fluid of the affected joint [1]. - This method directly confirms the presence of **monosodium urate crystals**, which are the hallmark of gout, offering diagnostic certainty [1]. *Uric acid in urine* - While urinary uric acid levels can help assess uric acid excretion, they are not diagnostic for acute gout and do not directly show the presence of **intra-articular crystals**. - This test is more relevant for investigating the **cause of hyperuricemia** (overproduction vs. underexcretion) rather than diagnosing an acute flare. *Anti CCP antibodies* - **Anti-cyclic citrullinated peptide (anti-CCP) antibodies** are markers for **rheumatoid arthritis** and are not relevant for the diagnosis of acute gout. - Their presence indicates an autoimmune inflammatory condition distinct from crystal-induced arthropathy. *Serum uric acid* - Serum uric acid levels are often elevated during an acute gout flare (**hyperuricemia**), but this is not diagnostic, as many individuals with hyperuricemia never develop gout [1]. - Approximately 30% of patients may have **normal serum uric acid levels** during an acute attack, making it an unreliable sole diagnostic criterion.
Question 6: Diagnosis of Gout is confirmed by which test?
- A. X- ray changes
- B. Urine uric acid levels
- C. Synovial fluid analysis (Correct Answer)
- D. Serum Uric acid level
Explanation: ***Synovial fluid analysis*** - Diagnosis of gout is definitively confirmed by the presence of **negatively birefringent, needle-shaped urate crystals** within neutrophils in the synovial fluid [1]. - This direct visualization of crystals confirms the diagnosis and differentiates gout from other forms of arthritis [1]. *X-ray changes* - While X-rays can show characteristic changes in chronic gout, such as **punched-out erosions with overhanging edges** (rat-bite erosions), these are not diagnostic of acute gout and may appear late in the disease course. - X-ray findings are less specific and do not confirm the presence of urate crystals. *Urine uric acid levels* - Urine uric acid levels help to distinguish between **overproducers and underexcreters** of uric acid, which can guide long-term management strategies [1]. - However, they do not directly confirm the diagnosis of an acute gouty attack. *Serum Uric acid level* - Elevated serum uric acid (hyperuricemia) is a prerequisite for gout, but many individuals with hyperuricemia never develop gout [1]. - Therefore, a **high serum uric acid level alone is not sufficient** to diagnose gout, especially during an acute attack when levels can sometimes be normal [1].
Question 7: In a patient with gouty arthritis, synovial fluid aspiration will show which of the following:
- A. Calcium pyrophosphate crystals
- B. Polymorphonuclear leukocytosis
- C. Monosodium urate crystals (Correct Answer)
- D. Mononuclear leukocytosis
Explanation: ***Monosodium urate crystals*** - **Gouty arthritis** is pathognomonically characterized by the presence of **monosodium urate (MSU) crystals** in the synovial fluid [1]. - These crystals are typically **needle-shaped** and display **strong negative birefringence** under polarized light microscopy [1]. *Mononuclear leucocytosis* - While present in inflammatory conditions, a predominance of **mononuclear cells** is less typical for acute gout [1]. - **Pseudogout** or even some chronic arthritides are more likely to exhibit this pattern. *Calcium pyrophosphate crystals* - These crystals are characteristic of **pseudogout**, also known as **calcium pyrophosphate deposition disease (CPPD)** [2]. - They are typically **rhomboid-shaped** and show **positive birefringence** [2]. *Polymorphonuclear leukocytosis* - Although there is an inflammatory response with increased **polymorphonuclear leukocytes (PMNs)** in gout, their presence alone is not specific for gout [1]. - **Septic arthritis** also presents with a significant increase in PMNs, and the definitive diagnosis relies on identifying the specific crystals or infectious agents. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1218-1220. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 683-684.
Question 8: A 58-year-old man with a diagnosis of chronic myeloid leukemia is treated with intensive chemotherapy. He goes into remission but develops pain in the left wrist. On physical examination, there is swelling and warmth on the palpation of the wrist. Polarized light microscopy of fluid aspirated from the wrist joint shows needle-shaped crystals that display negative birefringence. Which of the following processes most likely played an important role in the pathogenesis of the patient's wrist pain?
- A. Cytokine-induced synovial proliferation
- B. Excessive production of uric acid (Correct Answer)
- C. Abnormal platelet function with joint hemorrhages
- D. Chemotherapeutic toxicity to the articular cartilage
Explanation: ***Excessive production of uric acid*** - The patient's history of **chronic myeloid leukemia (CML)** and subsequent intensive chemotherapy can lead to rapid **cell turnover** and lysis, releasing large amounts of purines. The metabolism of these purines results in a significant increase in **uric acid production** [2]. - The presence of **needle-shaped crystals with negative birefringence** in the synovial fluid is pathognomonic for **gout**, which is caused by the precipitation of **monosodium urate crystals** due to hyperuricemia [1]. *Cytokine-induced synovial proliferation* - While cytokines can play a role in inflammatory arthropathies, **cytokine-induced synovial proliferation** is not directly indicated by the presence of **needle-shaped crystals** with negative birefringence. - This process is more typical of **rheumatoid arthritis** or other inflammatory conditions where crystal deposition is not the primary pathology. *Abnormal platelet function with joint hemorrhages* - **Abnormal platelet function** leading to joint hemorrhages (hemarthrosis) causes a different clinical picture, usually presenting with a history of bleeding disorders or trauma. - The microscopic finding of **needle-shaped crystals with negative birefringence** is not consistent with hemarthrosis. *Chemotherapeutic toxicity to the articular cartilage* - Although chemotherapy can have various side effects, **direct toxicity to articular cartilage** causing acute, painful arthritis with crystal deposition is not a classic presentation. - Chemotherapy-induced arthralgia is usually diffuse and does not typically involve the formation of diagnostic crystals in the joint fluid.
Question 9: 45-year-old man presented to outpatient department with hot, swollen left big toe and a painful lesion on the rim of his left pinna. Polarized light microscopy of the synovial fluid shows dense neutrophilic infiltrate and crystals that are negatively birefringent. Patient is likely to be suffering from?
- A. Gout (Correct Answer)
- B. Ankylosing spondylitis
- C. Rheumatoid arthritis
- D. Seronegative arthritis
Explanation: ***Gout*** - The presentation of a **hot, swollen left big toe** (podagra), a painful lesion on the **helix of the ear**, and **negatively birefringent crystals** in synovial fluid is classic for gout [1]. - These crystals are **monosodium urate**, formed from elevated uric acid levels, depositing in joints and soft tissues [1]. *Ankylosing spondylitis* - This condition primarily affects the **axial skeleton**, causing chronic back pain and stiffness that improves with exercise, and would not present with acute podagra or ear lesions. - While it can be associated with **HLA-B27**, its synovial fluid findings would not include negatively birefringent crystals. *Rheumatoid arthritis* - Characterized by **symmetric polyarthritis** primarily affecting small joints, morning stiffness lasting over 30 minutes, and typically involves positive **rheumatoid factor** and **anti-CCP antibodies**. - Synovial fluid in rheumatoid arthritis would show inflammatory changes but not the specific negatively birefringent crystals seen in gout [1]. *Seronegative arthritis* - This is a broad category including conditions like **psoriatic arthritis, reactive arthritis, and ankylosing spondylitis**, all of which lack **rheumatoid factor**. - None of these conditions typically present with **negatively birefringent crystals** in joint fluid or **tophi-like lesions** on the ear helix [1].
Question 10: Which of these is characteristic of gout?
- A. Podagra (Correct Answer)
- B. Anasarca
- C. Calcinosis cutis
- D. Cheiroarthropathy
Explanation: ***Podagra*** - This refers to the **inflammation of the big toe**, which is a classic presentation of gout [2]. - Gout is characterized by an **acute attack** of arthritis, commonly affecting peripheral joints, notably the **first metatarsophalangeal joint** [1]. *Cheiroarthropathy* - This condition involves **joint stiffness** and deformity, typically seen in **diabetes mellitus**, not gout. - It does not present with the **acute, inflammatory attacks** characteristic of gout [1]. *Calcinosis cutis* - This is a skin condition involving **calcium deposits**, often seen in **systemic sclerosis** or dermatomyositis. - It is not directly related to the **uric acid metabolism** issues or **joint inflammation** seen in gout. *Anasarca* - This term describes **generalized edema**, which can result from various conditions like heart failure or renal failure. - It is not specific to gout and does not involve the **acute joint inflammation** hallmark of the disease [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1218. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1218-1220.
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