Final answer:
Gout is characterized by negatively birefringent monosodium urate crystals, while pseudogout is identified by positively birefringent calcium pyrophosphate dihydrate crystals under polarized light microscopy.
Step-by-step explanation:
Microscopic Findings for Gout and Pseudogout
The microscopic findings for gout and pseudogout are distinct and can help differentiate between these two conditions. In gout, the presence of negatively birefringent monosodium urate (MSU) crystals is characteristic. These crystals are needle-shaped and can be visualized using polarized light microscopy where they exhibit strong negative birefringence, appearing as yellow when aligned parallel to the light axis and blue when perpendicular.
In contrast, pseudogout, also known as calcium pyrophosphate deposition (CPPD) disease, is characterized by the presence of positively birefringent calcium pyrophosphate dihydrate (CPPD) crystals. These crystals tend to be rhomboid shaped and will appear blue when aligned parallel to the light axis and yellow when perpendicular, the opposite of MSU crystals found in gout.
Both gout and pseudogout result in joint inflammation and pain but have different pathophysiologies and treatment approaches. It is important for accurate diagnosis and management to identify the type of crystals present, as this directly influences the treatment plan. A joint fluid analysis to visualize and analyze the crystals is a definitive diagnostic method for these conditions.