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|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|Prompt=A 62-year-old woman known to have osteoarthritis is hospitalized for pneumonia for which she receives an intravenous course of antibiotics.  On her third day of hospitalization, she reports improvement in her respiratory status but complains of a new onset of knee pain that started in the morning and progressively worsened throughout the day.  The knee is red, swollen and tender upon palpation.  Her temperature is 37 °C (98.6 °F), blood pressure is 120/70 mmHg and heart rate of 70/min.  Analysis of the synovial fluid reveals deposition of rhomboid crystals.  Which other features characterizes the crystals deposited in this patient’s joint?
|Prompt=A 62-year-old woman known to have osteoarthritis is hospitalized for pneumonia for which she receives an intravenous course of antibiotics.  On her third day of hospitalization, she reports improvement in her respiratory status but complains of a new onset of knee pain that started in the morning and progressively worsened throughout the day.  The knee is red, swollen and tender upon palpation.  Her temperature is 37 °C (98.6 °F), blood pressure is 120/70 mmHg and heart rate of 70/min.  Analysis of the synovial fluid reveals deposition of rhomboid crystals.  Which other features characterizes the crystals deposited in this patient’s joint?
|Explanation=Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, also known as chondrocalcinosis, pseudogout and pyrophosphate arthropathy is a rheumatologic disorder with varied symptoms and signs arising from the accumulation of crystals of calcium pyrophosphate dihydrate in the connective tissues.  [[Pseudogout]] usually involves larger joints such as the knees.  [[Hyperparathyroidism]], [[hypothyroidism]], [[hemochromatosis]], hypophosphatemia, hypomagnesemia and renal osteodystrophy are often also associated with chondrocalcinosis.  Other diseases associated with [[chondrocalcinosis]] are [[Wilson's disease]] and [[osteoarthritis]]. In some cases, traumatic arthritis can cause chondrocalcinosis.  X-rays of the joint helps in the diagnosis of chondrocalcinosis by depicting calcification of the cartilage. Synovial fluid analysis reveals rhomboidal crystals which exhibit weakly positive birefringence under polarized light.
|Explanation=Chondrocalcinosis or pseudogout is a disorder characterized by joint inflammation due to accumulation of crystals of calcium pyrophosphate dihydrate in the connective tissues.  Pseudogout resembles the gout but classically involves the larger joints very early on (eg. knee joint).  There are several disorders associated with chondrocalcinosis including hemochromatosis, hyperparathyroidism, renal osteodystrophy, and hypothyroidism. Joint X-rays classically demonstrate visible calcifications in the cartilage. Synovial fluid analysis reveals rhomboidal crystals which exhibit weak positive birefringence under polarized light microscopy in contrast to the needle-shaped strongly negative birefringent crystals observed in patients with gouty arthritis.
|AnswerA=Eosinophilic
|AnswerA=Eosinophilic
|AnswerAExp=Eosinophilic crystals are characteristics of gout and not pseudogout.
|AnswerAExp=Eosinophilic crystals are characteristics of gout and not pseudogout.
|AnswerB=Weak birefringence
|AnswerB=Weak positive birefringence
|AnswerBExp=In pseudogout, rhomboidal crystals exhibit weakly positive birefringence under polarized light.
|AnswerBExp=In pseudogout, rhomboidal crystals exhibit weakly positive birefringence under polarized light.
|AnswerC=Yellow when parallel to light
|AnswerC=Yellow when parallel to light
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|AnswerE=Hexagonal shape
|AnswerE=Hexagonal shape
|AnswerEExp=In pseudogout, crystals have a rhomboid shape and not a hexagonal shape.
|AnswerEExp=In pseudogout, crystals have a rhomboid shape and not a hexagonal shape.
|EducationalObjectives=In psudogout, synovial fluid analysis reveals rhomboidal crystals which exhibit weakly positive birefringence under polarized light.
|EducationalObjectives=In pseudogout, synovial fluid analysis reveals rhomboidal crystals which exhibit weak positive birefringence under polarized light microscopy.
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=Pseudogout, crystal, Arthritis,
|WBRKeyword=Pseudogout, Crystal, Arthritis, Gout, CPPD, Chondrocalcinosis
|Approved=No
|Approved=Yes
}}
}}

Revision as of 19:26, 9 March 2015
Author [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathophysiology
Sub Category SubCategory::Musculoskeletal/Rheumatology
Prompt [[Prompt::A 62-year-old woman known to have osteoarthritis is hospitalized for pneumonia for which she receives an intravenous course of antibiotics. On her third day of hospitalization, she reports improvement in her respiratory status but complains of a new onset of knee pain that started in the morning and progressively worsened throughout the day. The knee is red, swollen and tender upon palpation. Her temperature is 37 °C (98.6 °F), blood pressure is 120/70 mmHg and heart rate of 70/min. Analysis of the synovial fluid reveals deposition of rhomboid crystals. Which other features characterizes the crystals deposited in this patient’s joint?]]
Answer A AnswerA::Eosinophilic
Answer A Explanation AnswerAExp::Eosinophilic crystals are characteristics of gout and not pseudogout.
Answer B AnswerB::Weak positive birefringence
Answer B Explanation AnswerBExp::In pseudogout, rhomboidal crystals exhibit weakly positive birefringence under polarized light.
Answer C AnswerC::Yellow when parallel to light
Answer C Explanation AnswerCExp::Crystals that are yellow when parallel to light are characteristic of gout and not pseudogout.
Answer D AnswerD::Blue when perpendicular to light
Answer D Explanation AnswerDExp::Crystals that are blue when perpendicular to light are characteristic of gout and not pseudogout.
Answer E AnswerE::Hexagonal shape
Answer E Explanation AnswerEExp::In pseudogout, crystals have a rhomboid shape and not a hexagonal shape.
Right Answer RightAnswer::B
Explanation [[Explanation::Chondrocalcinosis or pseudogout is a disorder characterized by joint inflammation due to accumulation of crystals of calcium pyrophosphate dihydrate in the connective tissues. Pseudogout resembles the gout but classically involves the larger joints very early on (eg. knee joint). There are several disorders associated with chondrocalcinosis including hemochromatosis, hyperparathyroidism, renal osteodystrophy, and hypothyroidism. Joint X-rays classically demonstrate visible calcifications in the cartilage. Synovial fluid analysis reveals rhomboidal crystals which exhibit weak positive birefringence under polarized light microscopy in contrast to the needle-shaped strongly negative birefringent crystals observed in patients with gouty arthritis.

Educational Objective: In pseudogout, synovial fluid analysis reveals rhomboidal crystals which exhibit weak positive birefringence under polarized light microscopy.
References: ]]

Approved Approved::Yes
Keyword WBRKeyword::Pseudogout, WBRKeyword::Crystal, WBRKeyword::Arthritis, WBRKeyword::Gout, WBRKeyword::CPPD, WBRKeyword::Chondrocalcinosis
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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