Acute monoarthritis associated with lipid liquid crystals

Area of Science:

• Rheumatology
• Crystal-induced Arthropathies
• Synovial Fluid Analysis

Background:

• Acute monoarthritis presents a diagnostic challenge, particularly when crystal analysis is inconclusive.
• Understanding novel crystal types in synovial fluid is crucial for accurate diagnosis and treatment.

Observation:

• Three women presented with acute, unexplained monoarthritis.
• Synovial fluid revealed birefringent lipid microspherules and non-birefringent lipid globules.
• Leukocyte counts were elevated with a predominance of polymorphonuclear cells.

Findings:

• The birefringent microspherules were alcohol-ether soluble and uricase resistant, suggesting a lipid nature.
• Transmission electron microscopy confirmed osmiophilic material within phagocytic vacuoles.
• Serum lipid profiles and lipase levels were normal, ruling out common causes of hyperlipidemia.

Implications:

• Birefringent lipid microspherules represent a potential cause of acute, unexplained arthritis.
• These lipid crystals may induce synovial inflammation, mimicking other crystal-induced arthropathies.
• Identification of these microspherules aids in differential diagnosis and appropriate therapeutic strategies, including colchicine and NSAIDs.