Differential diagnosis of pseudogout of the lumbar spine.

This case report details a rare instance of calcium pyrophosphate dihydrate crystal deposition disease (CPPD), commonly known as pseudogout, affecting the lumbar spine. A man in his mid-50s of age presented with severe low-back pain and fever, initially suspected as a spinal infection. Elevated erythrocyte sedimentation rate and leucocytosis were observed, while the initial imaging showed only lumbar spondylosis with arthritic changes in the right L4-L5 facet joint. However, an MRI revealed a cystic lesion at the right L5-S1 facet joint without signs of spondylodiscitis. Ultrasound-guided needle aspiration and synovial fluid analysis, including polarised light microscopy, identified calcium pyrophosphate crystals. Treatment with intravenous pain management was initially ineffective. Confirmation of CPPD led to successful treatment with oral colchicine, resulting in rapid pain alleviation and fever reduction. The patient reported significant improvement at a 2-week follow-up. This case emphasises the importance of thorough investigation in differentiating common symptoms and avoiding unnecessary treatments, highlighting the role of histological examination in diagnosing rare conditions like spinal CPPD.

Acute Neck Pain from Crowned Dens Syndrome: A Case Report and Clinical Insights.

BACKGROUND Crowned dens syndrome (CDS) is a rare condition characterized by deposition of calcium pyrophosphate crystals on the odontoid process of the second cervical vertebra, forming a calcified 'crown', with neck pain being a common symptom. The disorder exhibits unique clinical and radiological features, resembling manifestations of meningitis, such as acute headaches and cervical stiffness. There are few case reports and case series related to CDS. Patients generally respond well to treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), although there is a certain rate of recurrence. Since there are few reports of CDS, we sought to publish this case report, aiming of increasing clinicians' awareness and reducing misdiagnosis rates. CASE REPORT A 62-year-old man presented to the Emergency Department with "cutting-like" headaches and neck pain for 2 days, and was subsequently diagnosed with CDS by cervical computed tomography (CT) scan, and hematological tests revealed inflammatory manifestations. He was advised to take oral nonsteroidal anti-inflammatory drugs and to rest; his symptoms improved after 3 days and his neck pain had almost resolved after 2 months. CONCLUSIONS In older patients experiencing new headaches and neck pain, along with increased inflammatory markers, particularly those with a history of pseudogout, the possibility of CDS should be considered. Case reports suggest that oral NSAIDs and short courses of corticosteroids can generally alleviate symptoms. Further research is needed on CDS diagnosis and treatment.

Calcium Pyrophosphate Crystal Formation and Deposition: Where Do we Stand and What Does the Future hold?

PURPOSE OF THE REVIEW: Although calcium pyrophosphate deposition (CPPD) has been known since the 1960s, our understanding of its pathogenesis remains rudimentary. This review aims to illustrate the known mechanisms underlying calcium pyrophosphate (CPP) crystal formation and deposition and explore future directions in research. By examining various perspectives, from basic research to clinical and imaging assessments, as well as new emerging methodologies, we can establish a starting point for a deeper understanding of CPPD pathogenesis. RECENT FINDINGS: Recent years have seen significant advances in CPPD research, particularly in the clinical field with the development of the 2023 ACR/EULAR classification criteria for CPPD disease, and in imaging with the introduction of the OMERACT ultrasonographic definitions and scoring system. However, progress in basic research has been slower. New laboratory approaches, such as Raman spectroscopy and omics sciences, offer promising insights that may help piece together the puzzle of CPPD. CPPD is a common yet understudied condition. As the population ages and CPPD becomes more prevalent, there is an urgent need to better understand the disease and the mechanisms involved in crystal formation and deposition, in order to improve diagnosis and therapeutic approaches.

Crowned Dens Syndrome-Pseudogout of the Neck.

This is a case report of a patient who presented with neck pain and intermittent pyrexia as a manifestation of pseudogout of the neck.

Systematic literature review to inform the EULAR recommendations for the use of imaging in crystal-induced arthropathies in clinical practice.

OBJECTIVE: To summarise current data regarding the use of imaging in crystal-induced arthropathies (CiAs) informing a European Alliance of Associations for Rheumatology task force. METHODS: We performed four systematic searches in Embase, Medline and Central on imaging for diagnosis, monitoring, prediction of disease severity/treatment response, guiding procedures and patient education in gout, calcium pyrophosphate dihydrate deposition (CPPD) and basic calcium phosphate deposition (BCPD). Records were screened, manuscripts reviewed and data of the included studies extracted. The risk of bias was assessed by validated instruments. RESULTS: For gout, 88 studies were included. Diagnostic studies reported good to excellent sensitivity and specificity of dual-energy CT (DECT) and ultrasound (US), high specificity and lower sensitivity for conventional radiographs (CR) and CT. Longitudinal studies demonstrated sensitivity to change with regard to crystal deposition by US and DECT and inflammation by US and structural progression by CR and CT. For CPPD, 50 studies were included. Diagnostic studies on CR and US showed high specificity and variable sensitivity. There was a single study on monitoring, while nine assessed the prediction in CPPD. For BCPD, 56 studies were included. There were two diagnostic studies, while monitoring by CR and US was assessed in 43 studies, showing a reduction in crystal deposition. A total of 12 studies with inconsistent results assessed the prediction of treatment response. The search on patient education retrieved two studies, suggesting a potential role of DECT. CONCLUSION: This SLR confirmed a relevant and increasing role of imaging in the field of CiAs.

Diagnostic Accuracy of Raman Spectroscopy Integrated With Polarized Light Microscopy for Calcium Pyrophosphate-Associated Arthritis.

OBJECTIVE: We studied the performance of integrated Raman polarized light microscopy (iRPolM) for the identification of calcium pyrophosphate (CPP)-associated arthritis (CPPD). METHODS: This is a diagnostic accuracy study including 400 consecutive synovial fluid samples from a single hospital in the Netherlands. Accuracy measures were calculated against polarized light microscopy (PLM) and the 2023 American College of Rheumatology (ACR)/EULAR criteria set for CPPD. RESULTS: The interrater reliability between iRPolM and the 2023 ACR/EULAR criteria set for CPPD was strong (κ = 0.88). The diagnostic performance of iRPolM compared to the 2023 ACR/EULAR criteria set was sensitivity 86.0% (95% confidence interval [CI] 73.3-94.2), specificity 99.1% (95% CI 97.5-99.8), positive likelihood ratio 100.33 (95% CI 32.3-311.3), negative likelihood ratio 0.14 (95% CI 0.07-0.28), positive predictive value 93.5% (95% CI 82.2-97.8), negative predictive value 98.0% (95% CI 82.2-97.8), and accuracy 97.5% (95% CI 95.5-98.8). We allowed rheumatologists to rate the certainty of their microscopic identification of CPP and found a large correspondence between iRPolM and a certain identification (κ = 0.87), whereas only 10% of the uncertain CPP identifications could be confirmed with iRPolM. We identified several novel particle types in synovial fluid analysis, including calcium carbonate crystals, deposited carotenoids, microplastics, and three types of Maltese cross birefringent objects. CONCLUSION: iRPolM can easily identify CPP crystals with a strong diagnostic performance. PLM alone is not specific enough to reliably resolve complicated cases, and the implementation of Raman spectroscopy in rheumatology practice can be of benefit to patients with suspected CPPD.

Crystal induced arthropathies-a comparative study of 40 patients with apatite rheumatism, chondrocalcinosis and primary synovial chondromatosis.

Introduction: Apatite rheumatism (AR), chondrocalcinosis (Ch-C), and primary synovial chondromatosis (prSynCh) are regarded as distinct clinical entities. The introduction of the non-staining technique by Bély and Apáthy (2013) opened a new era in the microscopic diagnosis of crystal induced diseases, allowing the analysis of MSU (monosodium urate monohydrate) HA (calcium hydroxyapatite), CPPD (calcium pyrophosphate dihydrate) crystals, cholesterol, crystalline liquid lipid droplets, and other crystals in unstained sections of conventionally proceeded (aqueous formaldehyde fixed, paraffin-embedded) tissue samples. The aim of this study was to describe the characteristic histology of crystal deposits in AR, Ch-C, and prSynCh with traditional stains and histochemical reactions comparing with unstained tissue sections according to Bély and Apáthy (2013). Patients and methods: Tissue samples of 4 with apatite rheumatism (Milwaukee syndrome), 16 with chondrocalcinosis, and 20 with clinically diagnosed primary synovial chondromatosis were analyzed. Results and conclusion: Apatite rheumatism, chondrocalcinosis, and primary synovial chondromatosis are related metabolic disorders with HA and CPPD depositions. The authors assume that AR and Ch-C are different stages of the same metabolic disorder, which differ from prSynCh in amorphous mineral production, furthermore in the production of chondroid, osteoid and/or bone. prSynCh is a defective variant of HA and CPPD induced metabolic disorders with reduced mineralization capabilities, where the deficient mineralization is replaced by chondroid and/or bone formation. The non-staining technique of Bély and Apáthy proved to be a much more effective method for the demonstration of crystals in metabolic diseases than conventional stains and histochemical reactions.

[First classification criteria for diseases caused by calcium pyrophosphate deposition (CPPD)-Translation, explanation and assessment]. / Erste Klassifikationskriterien für durch Kalziumpyrophosphatablagerungen verursachte Erkrankungen ­ Übersetzung, Erläuterung und Bewertung.

AIM: For diseases caused by calcium pyrophosphate deposition (CPPD), validated classification criteria were previously lacking. In this article the recently developed and validated classification criteria are translated, explained, and assessed. METHODS: In recent years a multinational research group developed classification criteria for CPPD disease with the support by the European Alliance of Associations for Rheumatology (EULAR) and the American College of Rheumatology (ACR), following an established method. The developed criteria were finally validated in an independent cohort. The translation and annotation of the new first classification criteria were carried out in an iterative procedure in consensus with the authors. RESULTS: The presence of a crowned dens syndrome or calcium pyrophosphate crystals in the synovial fluid in patients with pain, swelling or sensitivity of the joints (entry criterion) is sufficient for the classification as CPPD disease, where the symptoms cannot be completely explained by another rheumatic disease (exclusion criterion). If these symptoms are not present, a count of more than 56 points based on weighted criteria comprised of clinical features and the results of laboratory and imaging investigations can be included for classification as a CPPD disease. These criteria had a sensitivity of 92.2% and a specificity of 87.9% in the derivation cohorts (190 CPPD cases and 148 mimics), whereas the sensitivity was 99.2% and the specificity 92.5% in the validation cohorts (251 CPPD cases and 162 mimics). CONCLUSION: The ACR/EULAR classification criteria 2023 of a CPPD disease will facilitate clinical research in this field. The use in the clinical routine will show how practical the criteria are.

Synovial fluid crystal analysis with compensated polarization using a gout analyser in clinical practice.

OBJECTIVE: To validate the gout analyzer as a clinical method of synovial fluid crystal analysis. METHODS: Thirty knee synovial fluid samples with suspected calcium pyrophosphate (CPP) crystals were analyzed. Within 48 hours after collection, each non-centrifuged sample was examined blindly and independently by one or more rheumatologists in the following order: 1) with an optical microscope under ordinary light, 2) with the same microscope under compensated polarization provided by a gout analyzer, and 3) with a fully equipped compensated polarized microscope with a rotating stage as the gold standard. As a reference, laboratory technicians analyzed fresh, centrifuged synovial fluid using a gout analyzer. RESULTS: Of the 30 samples analyzed, CPP and monosodium urate (MSU) crystals were detected in 11 and four, non-centrifuged samples, respectively, using a fully equipped compensated polarized microscope. The rheumatologists' detection rate of crystals in the non-centrifuged synovial fluid under ordinary light and with a gout analyzer was 73.3% and 80%, respectively. The laboratory technicians' detection rate in fresh centrifuged synovial fluid using a gout analyzer was 100%. CONCLUSION: A gout analyzer may be used to diagnose gout and calcium pyrophosphate deposition disease definitively if a fully equipped compensated polarized microscope is unavailable.

Orthostatic hypotension as an unusual presentation of spinal calcium pyrophosphate deposition disease: case report and review of literature.

Calcium pyrophosphate crystal deposition disease (CPPD), also known as pseudogout, with spinal involvement, is associated with clinical manifestations of acute nerve compression or chronic spinal stenosis. Precipitation of crystals of calcium pyrophosphate dihydrate in connective tissues can lead to acute inflammatory arthritis, degenerative chronic arthropathies, and radiographic evidence of cartilage calcification. We present a case of an 87-year-old woman, with unstudied chronic polyarthralgia and symptomatic orthostatic hypotension. It were documented acute calcium pyrophosphate deposition wrist arthritis, and cervical CT and MRI was suggestive of spinal involvement of CPPD. Workup excluded other causes of OH. Surgical approach could be indicated to minimize the symptoms, but it was contra-indicated due to the patient's performance status, so histological diagnosis was not possible. Muscle atrophy played an important part in the rapid progression of this insidious chronic disease. Conservative and symptomatic treatment achieve scarce short-term clinical improvement. Spinal involvement of CPPD was thought to be rare but recent studies show a higher prevalence than expected. We call for attention to the extent of structural changes that may occur when not early diagnosed nor treated. High clinical suspicion is required and this is, to our knowledge, the first report of orthostatic hypotension as a presentation of CPPD.

Joint manifestations revealing inborn metabolic diseases in adults: a narrative review.

Inborn metabolic diseases (IMD) are rare conditions that can be diagnosed during adulthood. Patients with IMD may have joint symptoms and the challenge is to establish an early diagnosis in order to institute appropriate treatment and prevent irreversible damage. This review describes the joint manifestations of IMD that may be encountered in adults. The clinical settings considered were arthralgia and joint stiffness as well as arthritis. Unspecific arthralgias are often the first symptoms of hereditary hemochromatosis, chronic low back pain may reveal an intervertebral disc calcification in relation with alkaptonuria, and progressive joint stiffness may correspond to a mucopolysaccharidosis or mucolipidosis. Gaucher disease is initially revealed by painful acute attacks mimicking joint pain described as "bone crises". Some IMD may induce microcrystalline arthropathy. Beyond classical gout, there are also gouts in connection with purine metabolism disorders known as "enzymopathic gouts". Pyrophosphate arthropathy can also be part of the clinical spectrum of Gitelman syndrome or hypophosphatasia. Oxalate crystals arthritis can reveal a primary hyperoxaluria. Destructive arthritis may be indicative of Wilson's disease. Non-destructive arthritis may be seen in mevalonate kinase deficiency and familial hypercholesterolemia.

Synovial fluid analysis: Relevance for daily clinical practice.

Synovial fluid analysis can provide a prompt and definite diagnosis of crystal-induced arthritis, the most common acute inflammatory arthritis and a cause of chronic arthritis that may mimic rheumatoid, psoriatic, or peripheral spondyloarthritis. In many patients the diagnosis of gout or calcium pyrophosphate arthritis cannot be made with certainty without synovial fluid analysis. Additional information from fluid analysis can assist the clinician in honing the differential diagnosis of non-crystalline arthritis.

Crowned dens syndrome: A rare form of acute neck pain and headache that can be misdiagnosed or missed.

Crowned dens syndrome (CDS) occurs due to the deposition of calcium pyrophosphate (CPP) in the ligament tissue around the odontoid process of the axis. CDS is characterized by acute neck pain, stiffness, fever, and elevated inflammatory markers. It is a rare cause of neck pain among older people. We report a 71-year-old female patient who presented with acute neck pain, headache, with dizziness. Body temperature showed normal, with elevated C-reactive protein and ESR in the blood. Over the past 5 years, the patient has experienced neck and head pain several times.MRI of the head and CT scan of the neck showed calcification of the transverse atlantoaxial and cruciate ligament in combination with mild compression of the medulla oblongata. The patient was given non-steroidal anti-inflammatory drugs (NSAIDs) and colchicine for 10 days, with significant symptom improvement and no recurrence at 10 months of follow-up.

Differences in the Optical Response of MSU and CPP Crystals During Magnetic Orientation: Possibility of Diagnosing Gout and Pseudogout.

Pseudogout is crystalline arthritis. It has a similar clinical picture to that of gout, and it is difficult to distinguish the two diseases using conventional analysis methods. However, it is important to identify the different crystals responsible for these two cases because the treatment strategies are different. In a previous study, we reported magnetic orientation of monosodium urate (MSU) crystals, which are the causative agent of gout, at the permanent magnet level. In this study, we investigated the effect of an applied magnetic field on calcium pyrophosphate (CPP) crystals, which are the causative agent of pseudogout, and the difference in the magnetic responses of CPP and MSU crystals. We found that the CPP crystals were oriented in a magnetic field on milli-Tesla order because of the anisotropy of the diamagnetic susceptibility. In addition, the CPP crystals exhibited different anisotropic magnetic properties from those of MSU crystals, which led to a characteristic difference between the orientations of the two crystals. That is, we found that the causative agents of gout and pseudogout responded differently to a magnetic field. This report suggests that the discrimination between CPP and MSU by optical measurements is possible by application of magnetic fields appropriately. © 2023 Bioelectromagnetics Society.

Case report: crowned dens syndrome in a patient with seronegative rheumatoid arthritis.

Chondrocalcinosis (CC) is the one of the most common crystal pyrophosphate disease associated arthritis in the elderly. It has been shown to coexist with seronegative and seropositive rheumatoid arthritis (RA), yet mostly with seronegative RA. Among the localisation of CC, the deposition in the ligaments surrounding the odontoid process may remain asymptomatic for years or may lead to and acute severe symptomatology, which may mimic several clinical illnesses among which meningitis (fever, severe pain, acute phase reactants). This is called the 'crowned dens syndrome (CDS)', which has been reported to represent an important percentage of acute neck pain needing hospital admission in neurosurgery units. In this case, the rapid demonstration of 'crowned dens' through CT scan may allow to avoid lumbar puncture and cerebrospinal fluid examination. The coexistence of RA and CDS is very rare, and rarely reported in the literature, yet it may represent a clinical challenge. We describe here one case that while on therapy with methotrexate (MTX) and naproxen (NPX) had an acute neck pain, and peripheral arthritis flare, that responded well to colchicine given along with MTX and NPX.

A single-centre retrospective case series of Anakinra for incident calcium pyrophosphate deposition disease.

In this 2-year retrospective case series, we characterise the calcium pyrophosphate deposition disease (CPPD) inpatient cohort at a single centre and assess the efficacy and safety of anakinra in its treatment. Adult inpatients with CPPD between 1st September 2020 and 30th September 2022 were identified by ICD-10 codes and confirmed based on clinical diagnosis and either CPP crystals on aspirate or chondrocalcinosis on imaging. Charts were reviewed for demographic, clinical, biochemical data, treatment choice, and response. Response to treatment was determined from chart documentation and calculated from time of first CPPD treatment. Daily responses to anakinra were recorded if anakinra was used. Seventy patients accounting for 79 cases of CPPD were identified. Twelve cases received anakinra, whilst 67 cases received conventional therapy only. Patient receiving anakinra were predominantly male, had multiple comorbidities, and had higher CRPs and serum creatinine when compared to the non-anakinra group. Anakinra was rapidly effective with the mean time to substantial and complete response being 1.7 and 3.6 days respectively. Anakinra was well tolerated. This study adds to the small amount of retrospective data present about the use of anakinra in CPPD. We observed a rapid response to anakinra in our cohort with minimal adverse drug reactions. Key Points • Treatment of CPPD with anakinra appears to be rapidly efficacious without safety concerns.

Confirming Prior and Identifying Novel Correlates of Acute Calcium Pyrophosphate Crystal Arthritis.

OBJECTIVE: To investigate previously identified and novel correlates of acute calcium pyrophosphate (CPP) crystal arthritis among well-characterized cases. METHODS: In this case-control study, we identified cases of acute CPP crystal arthritis using a validated algorithm (positive predictive value 81%) applied in the Partners HealthCare electronic health record (EHR). Cases were matched to general patient controls on the year of first EHR encounter and index date. Prespecified potential correlates included sex, race, and comorbidities and medications previously associated with CPP deposition/acute CPP crystal arthritis in the literature. We estimated odds ratios (ORs) and 95% confidence intervals using conditional logistic regression models adjusted for demographic characteristics, comorbidities, medications prescribed in the past 90 days, health care utilization, and multimorbidity score. RESULTS: We identified 1,697 cases matched to 6,503 controls. Mean ± SD age was 73.7 ± 11.8 years, 56.7% were female, 80.8% were White, and 10.3% were Black. All prespecified covariates were more common in cases than controls. Osteoarthritis (OR 3.08), male sex (OR 1.35), rheumatoid arthritis (OR 2.09), gout (OR 2.83), proton pump inhibitors (OR 1.94), loop diuretics (OR 1.60), and thiazides (OR 1.46) were significantly associated with acute CPP crystal arthritis after full adjustment. Black race was associated with lower odds for acute CPP crystal arthritis compared to White race (OR 0.47). CONCLUSION: Using a validated algorithm to identify nearly 1,700 patients with acute CPP crystal arthritis, we confirmed important correlates of this acute manifestation of CPP deposition. This is the first study to report higher odds for acute CPP crystal arthritis among males.