Thick and yellowish articular effusion: a challenging diagnosis! Focus on cholesterol crystal deposition in joint

Excerpt

We reported a case of an 84-year-old woman with an old inability to actively elevate her left upper limb, with recent shoulder pain. X-ray showed an important arthropathy of the left gleno-humeral joint with epiphyseal osteonecrosis (Fig. 1a). Ultrasound examination showed a sub-acromial bursal thickening with a heterogeneous echogenicity (Fig. 1b). Bursal aspiration revealed a thick and yellowish synovial fluid (Fig. 1c). Microscopic examination revealed typical aspect of monohydrate cholesterol crystal (CC) (Fig. 1d–g). After centrifugation, some calcium pyrophosphate (CPP) crystals were also observed in synovial fluid. Apart from an inflammatory syndrome (CRP 56.6 mg/L), no other biological abnormalities were observed (negative rheumatoid factor and anti-citrullinated protein antibodies, normal carbohydrate-lipid). Neurogenic arthropathy was disproved with negative syphilitic serology and absence of diabetes mellitus. Long term synovial fluid bacterial culture was negative. Spinal, knee and pelvis X-rays revealed widespread CPP-crystal deposition. Final diagnosis was an advanced osteoarthritis probably induced by a CPP-deposition disease. Shoulder arthroplasty was suggested but the general state of this old woman did not allow this surgery.

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