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Monday, 30 September 2019

ARTRITIS GOTOSA POR CRISTALES DE URATO MONOSÓDICO

Written by Arturo González Raya | Ramón Coca Zúñiga | Fernando Miguel Cantero Sánchez, Posted in Volumen11

Figure 1. Example of gout crystals (monosodium urate crystals) visualized (40x objective) under polarized light with red compensator (black arrow indicates the axis of the compensator).

Synovial fluid (SF), is a dialysate of plasma that internally covers the cavities of synovial joints. It is formed by ultrafiltration of plasma in the synovial capillaries.

There are two types of cells on the synovial lining known as type "A" and "B" synoviocytes. The type A cells have phagocytic functions while the type B cells with secretion functions, add to the SF among other substances, mucopolysaccharides with high hyaluronate content that gives it the characteristic viscosity.
Figura1plus
Figure 1. Example of gout crystals (monosodium urate crystals) visualized (40x objective) under polarized light with red compensator (black arrow indicates the axis of the compensator).

Synovial fluid (SF), is a dialysate of plasma that internally covers the cavities of synovial joints. It is formed by ultrafiltration of plasma in the synovial capillaries.

There are two types of cells on the synovial lining known as type "A" and "B" synoviocytes. The type A cells have phagocytic functions while the type B cells with secretion functions, add to the SF among other substances, mucopolysaccharides with high hyaluronate content that gives it the characteristic viscosity.

The SF analysis is frequently requested to the clinical laboratory to guide the diagnosis of crystal arthropathies, infections and other rheumatological dysfunctions such as monoarthritis or joint effusion.

According to the recommendations of the American College of Rheumatology the SF evaluation includes:
  • Macroscopic study, refers to physical characteristics such as volume, color, viscosity, etc.
  • Microscopic study, includes the cell count and the examination for crystals with polarized light or stains.
  • Microbiological study, Gram stain and cultures.
  • Biochemical analysis.
Each one of these studies provides complementary information that allows clinicians to assess the state of the articulation and guide to correct diagnosis. The analysis of crystals in SF is basic for the diagnosis of microcrystal arthropathy, it is considered the reference standard for the diagnosis of gout.

The crystals responsible for gout are monosodium urate (MSU) (most common cause of arthropathy), calcium pyrophosphate that causes Pseudogout or chondrocalcinosis (second most common) and less frequently calcium oxalate, apatite and other phosphates basic calcium and lipids (mainly cholesterol).

Differentiating the crystals of MSU and pyrophosphate is of great importance since they are the most prevalent crystals. Its identification requires a polarizing microscope and above all of trained personnel to recognize the shape and optical characteristics.
  • MSU crystals: Needle-shaped crystals with an intense negative birefringence (crystals parallel to the compensator axis appear yellow and if they are perpendicularly blue).
  • Calcium pyrophosphate crystals (CPP). The CPP crystals are rhomboidal and positively birefringent (crystals parallel to the compensator axis appear blue and if they are perpendicular yellow).
The crystals must be tracked with a 10x objective and evaluated at least with the objective of 40x, paying special attention to the cellular areas. The complete examination of the liquid requires the use of the 100x objective to evaluate the presence of microcrystals in large quantities that can cause pathologies and go unnoticed.

We present a case of a 50-year-old man who presented with intense pain, increased volume and local heat in the left knee of 24 hours of evolution.

Serum colouring gradually faded out until the fourth day. The patient’s progress was favourable, probably because no serious organ failures were presented. On the fifth day, the patient was discharged.

Figura2Figure 2. Example of gout crystals visualized with the objective of 40x: light microscopy (left), dark polarized light (central image) and under polarized light with red compensator (right).

We present a case of a 50-year-old man who presented with intense pain, increased volume and local heat in the left knee of 24 hours of evolution. Puncture of the knee is performed by external prepatellar and cloudy liquid is obtained, white blood cell: 86,000 cel/μL and abundant crystals compatible with monosodium urate.

Bibliografía
  1. Jaroslava D. Cytology of synovial fluid. Cesk Patol 2019 Spring; 55(2):84-91.
  2. Ferreyra M et al. Combining cytology and microcrystal detection in nonpurulent joint fluid benefits the diagnosis of septic arthritis. Joint Bone Spine 2017; 84(1):65-70.
  3. Heselden EL, Freemont AJ. Synovial fluid findings and demographic analysis of patients with coexistent intra-articular monosodium urate and calcium pyrophosphate crystals. J Clin Rheumatol 2016; 22(2):68-70.
  4. Martínez-Castillo A, Nuñez C, Cabiedes J. Análisis de líquido synovial. Reumatol Clin 2010; 6(6):316-21.
  5. Ostovic KT et al. The importance of urgent cytological examination of synovial fluids in differentiation inflammatory and non-inflamatory joint diseases. Coll Antropol 2010; 34(1):145-52.
  6. Aramburu Albizuri JM, García Vivar ML, Galíndez Aguirregoika E, García Llorente JF. Interpretación de los hallazgos en el líquido sinovial de una artrocentesis. Medicine 2009; 10:2219-21.
  7. Gatter RA, Andrews RP, Cooley DA et al. American college of rheumatology guidelines for performing office synovial fluid examinations. J Clin Rheumatol 2005; 1:194-9).
 

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