Synovial xanthomatosis: are there clues to mechanisms for this rare disease?

We report a 64-year-old man with arthritis and nodules to describe that this picture can be caused by normo-lipidemic xanthomas. Light and electron microscopy (EM) plus polymerase chain reaction (PCR) studies were performed for diagnosis and investigation. These showed features typical of xanthomas plus PCR and EM evidence of possible infection with Chlamydia pneumoniae as a pathogenetic mechanism deserving consideration. With such rare diseases, any clues to possible mechanisms seem important to record and thus to encourage future investigations. This uncommon cause of arthritis and nodules had been confused with rheumatoid arthritis by others in this case.

Current trends in crystal identification.

PURPOSE OF REVIEW: This review is an attempt to keep current in the sparse literature addressing the still underutilized area of crystal identification. RECENT FINDINGS: The emphasis has been on the subtleties of the microscopic identification of common crystals and other less common potentially confusing crystals. Imaging is noted to provide increasing help, but microscopic crystal identification remains the gold standard. SUMMARY: Quality control is still a concern as is the infrequency of attempted arthrocentesis for crystal identification.

Prophylactic effect of highly selective COX-2 inhibition in acute monosodium urate crystal induced inflammation in the rat subcutaneous air pouch.

OBJECTIVE: To examine the ability of rofecoxib prophylaxis to blunt the effect of monosodium urate (MSU) crystal inflammation induced in the rat subcutaneous air pouch. METHODS: Eight rats were used in each of 4 groups. On day one, air was injected subcutaneously to create the pouches and gavage feedings were started with placebo or 2 different doses of rofecoxib. Six days later MSU crystals or saline were injected into the pouches. Twenty-four hours later, rats were examined, sacrificed, and pouch fluid studied. RESULTS: Rofecoxib 15 or 30 mg/kg given for 6 days before MSU crystal injection into rat air pouches significantly suppressed the inflammation following injection of 10 mg crystals (p = 0.001) and tended to suppress the milder inflammation induced by 5 mg MSU. Greater effects on phagocytosis were seen with 30 mg/kg rofecoxib. Tumor necrosis factor-alpha levels in pouch fluid measured by ELISA were not suppressed by the rofecoxib. CONCLUSION: Prophylactic use of this cyclooxygenase 2 (COX-2) selective inhibitor in this pilot study suppressed acute MSU crystal induced inflammation. Effects on cytokines need further investigation. COX-2 inhibitors deserve consideration for prophylactic use in interim gout.

Update on identification of pathogenic crystals in joint fluid.

Crystal identification in joint fluid has been an essential part of diagnosis of joint disease. Recent advances have included progress in crystal identification on stained slides, attention to aspiration techniques, and arthrocenteses of asymptomatic joints. Challenges remain to increase use and optimize techniques.

Ultrasonography for assessment of subcutaneous nodules.

OBJECTIVE: To characterize a variety of subcutaneous lesions by their ultrasonographic (US) appearance, and establish these images as a starting point to measure changes with treatments. METHODS: Twenty-six patients with 48 subcutaneous nodular swellings of various types were imaged using a portable US machine equipped with a 10 MHz linear transducer. All patients had a known diagnosis of a rheumatic disease. We used US to examine subcutaneous lesions and the underlying cortical surface of the bone or joint. Two measurements of some tophi and rheumatoid nodules were done on different dates to examine reproducibility of the measurements. RESULTS: Nodular lesions included 20 tophi and 20 rheumatoid nodules, 2 sarcoid nodules, 2 lipomas, and 4 synovial cysts. Tophi most often appeared as heterogeneous masses; hypoechoic areas in 2 tophi were decreased after aspiration of chalky liquid tophaceous material. Occasionally tophi had calcifications appearing hyperechoic with acoustic shadowing. Cortical bone erosions could be seen adjacent to some tophi. The nodules in patients with rheumatoid arthritis were often attached closely to the bone surface and less erosive to bone, allowing the cortical bone to be seen easily. The nodules were more homogeneous. Some showed a central sharply demarcated hypoechoic area, possibly corresponding to necrosis inside the rheumatoid nodules. Nodules were easily measured. The repeated measurements of both tophi and rheumatoid nodules showed excellent reproducibility. Lipomas had different echogenic patterns depending on composition of the associated connective tissue and position of the mass. They could be hypoechogenic, hyperechogenic, or mixed, but were easily distinguished by oval shapes with well demarcated capsules. Synovial cysts seen in this study had a characteristic hypoechoic pattern. CONCLUSION: Subcutaneous nodules examined by sonography show characteristics and patterns that, although not diagnostic, can be used to help distinguish their etiology. Tophi and rheumatoid nodules can be easily measured and these measurements used to help follow disease progression or response to therapy.