🩺 MEDLAB BOT AI • CLINICAL MLS MCQ
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📚 Specialty: Hematology & Clinical Microscopy (#HematologyampClinicalMicroscopy)
🎯 Difficulty: Intermediate
🔢 Item: #Q14
❓ QUESTION:
An acute arthrocentesis of the first metatarsophalangeal joint in a 54-year-old male yields turbid synovial fluid. Polarized light microscopy with a red compensator filter reveals needle-shaped intracellular crystals displaying strong negative birefringence. When the long axis of the crystals is oriented parallel to the slow-wave axis of the compensator, the crystals appear bright yellow. What type of crystal is present?
A) Monosodium urate (MSU)
B) Calcium pyrophosphate dihydrate (CPPD)
C) Cholesterol
D) Calcium oxalate
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✅ CORRECT ANSWER: Option A
💡 CLINICAL RATIONALE & DIAGNOSTIC PEARLS:
Monosodium urate (MSU) crystals (diagnostic of gout) are characteristically needle-shaped with strong negative birefringence. Under polarized light with a red compensator, they appear yellow when aligned parallel to the slow axis of the compensator filter and blue when perpendicular. Calcium pyrophosphate dihydrate (CPPD) crystals (pseudogout) are rhomboid and weakly positively birefringent (blue when parallel).
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📢 MedLab Bot AI • Official Clinical Series
━━━━━━━━━━━━━━━━━━━━━━━━━━
📚 Specialty: Hematology & Clinical Microscopy (#HematologyampClinicalMicroscopy)
🎯 Difficulty: Intermediate
🔢 Item: #Q14
❓ QUESTION:
An acute arthrocentesis of the first metatarsophalangeal joint in a 54-year-old male yields turbid synovial fluid. Polarized light microscopy with a red compensator filter reveals needle-shaped intracellular crystals displaying strong negative birefringence. When the long axis of the crystals is oriented parallel to the slow-wave axis of the compensator, the crystals appear bright yellow. What type of crystal is present?
A) Monosodium urate (MSU)
B) Calcium pyrophosphate dihydrate (CPPD)
C) Cholesterol
D) Calcium oxalate
━━━━━━━━━━━━━━━━━━━━━━━━━━
✅ CORRECT ANSWER: Option A
💡 CLINICAL RATIONALE & DIAGNOSTIC PEARLS:
Monosodium urate (MSU) crystals (diagnostic of gout) are characteristically needle-shaped with strong negative birefringence. Under polarized light with a red compensator, they appear yellow when aligned parallel to the slow axis of the compensator filter and blue when perpendicular. Calcium pyrophosphate dihydrate (CPPD) crystals (pseudogout) are rhomboid and weakly positively birefringent (blue when parallel).
━━━━━━━━━━━━━━━━━━━━━━━━━━
📢 MedLab Bot AI • Official Clinical Series