Calcium pyrophosphate deposition disease

Pseudogout, chondrocalcinosis, CPPD et al: crystal clear… or clear as mud?-The time has come to reconsider the nomenclature of calcium pyrophosphate deposition

Scientific interest in calcium pyrophosphate deposition (CPPD) has been limited by several challenges. These include difficulties in diagnosis due to diverse clinical presentations, the lack of classification criteria, the absence of standardised diagnostic modalities, underrecognition in clinical care, and, most significantly, the lack of evidence-based treatments. Consequently, CPPD was often regarded as the 'poor cousin' of gout. Fortunately, in recent years, CPPD has garnered increased attention from the rheumatology community. Milestones such as the first American College of Rheumatology/European Alliance of Association for Rheumatology classification criteria, the European Alliance of Association for Rheumatology recommendations for the use of imaging in clinical practice, validated OMERACT ultrasound definitions and scoring system, and the OMERACT core domain sets for CPPD have significantly advanced the field. Yet, unresolved issues regarding CPPD nomenclature hold back advancement in both research and clinical practice. The terminology surrounding CPPD remains inconsistent in the scientific literature, with numerous terms and acronyms used to describe the condition and its manifestations. For example, many 'pseudosyndromes' (eg, pseudogout) and purely radiographic descriptors (eg, chondrocalcinosis) are still commonly used by clinicians and researchers interchangeably, as either the name of the condition or one of its clinical or radiographic manifestations. This lack of standardisation complicates communication among health care professionals, researchers, and between doctors and patients, creating insurmountable barriers to effective care and research advances. In this viewpoint, we highlight the value of standardised terminology, drawing parallels with other rheumatic diseases. We aimed to explore the historical evolution of CPPD nomenclature, assess the impact of previous standardisation efforts, and propose a possible way for a common language.

Clinical features and diagnostic challenges in crowned dens syndrome: a systematic review and meta-analysis

Crowned Dens Syndrome (CDS) is an acute inflammatory neck pain linked to Calcium Pyrophosphate crystal deposition surrounding the odontoid process. This systematic review and meta-analysis aim to illuminate the Features and Diagnostic Challenges of CDS. PubMed, Web of Sciences, and Scopus databases were searched in July 2024 to include all studies on CDS without publication year or language restrictions. Demographic, clinical, laboratory, and radiological data, in addition to treatment regimens and outcomes, were extracted and analyzed. PROSPERO registration number is CRD42024575491. We analyzed 153 reports, including 196 CDS patients, with a mean age of 73.13 ± 12.95 years and an almost equal female-to-male ratio. Neck pain was the most common symptom (96.8%). CRP and ESR were elevated in 91.4% and 80.7% of cases, respectively. CT scans had the highest detection rate for abnormalities (97.3%), compared to MRI (68.4%) and plain radiographs (79.4%). NSAIDs were the most frequently used treatment (62.5%), with improvement observed in 96.6% of cases. Meningitis was the most common misdiagnosis (21.4%), leading to a higher likelihood of plain radiographs and lumbar punctures. In contrast, patients with neck tenderness and restricted range of motion had a lower risk of misdiagnosis. Patients who were initially misdiagnosed were more likely to undergo LP (13.1% Vs. 34.8%; P-value < 0.001). CDS is an elderly disease that usually presents as acute neck pain with elevated inflammatory markers and is frequently misdiagnosed as meningitis. Recognizing key clinical features may improve diagnosis and management.

Combined Gout and Pseudogout Demonstrate Unique Clinicopathologic Features Compared to Those With Only Gout

Although monosodium urate and calcium pyrophosphate dihydrate (CPPD) crystals have been documented together in synovial fluid, there are no descriptions regarding their simultaneous histologic presence within the same tophi. Furthermore, the incidence, significance, and clinicopathologic features of such patients have not been analyzed. We retrospectively reviewed consecutive cases of pathologic specimens over an ~4-year period with a confirmed histologic diagnosis of "gout" or "gouty tophi", focusing on concomitantly documented CPPD. A total of 159 gout cases involved 156 patients, including 127 males and 29 females (ratio 4.4:1), with ages ranging from 14 to 99 years (median 67). Nine (5.7%) patients (6 males; 3 females; ratio 2:1; age range 49 to 91 years, median 74) had evidence of both gout and CPPD crystals within the same tophaceous deposits. Concomitant gout/CPPD were more commonly associated with the upper extremities (5 [3, hands; 2, elbows]) than lower extremities (4, feet). Seven patients had a prior history of gout and 1 CPPD. The 150 cases from 147 patients of gout alone occurred in 121 males and 26 females (ratio 4.7:1), with ages ranging from 14 to 99 years (median 67). Gout alone was far more common in the lower extremities (109 cases) than the upper extremities (41). For combined gout/pseudogout, deposits of CPPD were intimately associated with the gouty tophi, deposited in irregular, curvilinear to serpiginous aggregates onto a significantly higher volume of uric acid crystals but never observed away from the tophaceous deposits. Confirmation of the uric acid crystals required polarization of unstained sections. In conclusion, the presence of concomitant CPPD and gouty crystals in the same tophaceous deposits is infrequently observed in pathology specimens. Compared with gout only, preliminary data suggests that patients with combined gout/pseudogout tophi are more likely to be older, female, and exhibit upper extremity involvement. Most such patients also have a prior history of gout.

Imaging of crystal-induced arthropathies in 2025

In recent years, imaging has become an essential tool in the assessment of crystal-induced arthropathies (CIAs), including gout, calcium pyrophosphate deposition disease, and basic calcium phosphate crystal deposition. Advances in imaging have improved diagnosis and disease monitoring, leading to its integration into classification criteria and clinical guidelines. Ultrasound (US), conventional radiography (CR), and dual-energy computed tomography (DECT) each offer unique advantages. US is a widely accessible, cost-effective, and dynamic tool, while DECT provides crystal-specific images, aiding particularly in gout diagnosis. CR, though less sensitive to early crystal deposition, remains valuable for evaluating structural damage and chronic changes. Despite these advances, challenges remain. The specificity and sensitivity of imaging findings need further validation, and the clinical relevance of certain imaging features is debated. This review summarizes recent developments, highlights key strengths, and discusses unresolved issues, emphasizing areas where future research is needed to optimize imaging use in CIAs.

Updates in Deposition Arthritis Other Than Gout

This article focuses on updates in calcium pyrophosphate deposition disease (CPPD) and basic calcium phosphate deposition (BCPD), highlighting recent advances in imaging and the understanding of these conditions. It explores their clinical presentations, crystal formation mechanisms, and diagnostic challenges. CPPD and BCPD are often underrecognized causes of arthritis, and recent imaging diagnostic criteria are presented.

Multitargeted biological actions of polydatin in preventing pseudogout acute attack

Introduction

We have recently shown that polydatin (PD) prevents calcium pyrophosphate (CPP) crystal-induced arthritis in mice. This study aims to explore potential mechanisms of action associated with this anti-inflammatory effect.

Materials and methods

Acute arthritis was induced in Balb/c mice by the injection of crystals into the ankle joint. Animals were randomised to receive PD or colchicine according to a prophylactic protocol. Ankle swelling was measured and both joints and muscles were harvested at sacrifice. Histological evaluations were performed using H&E staining to assess cartilage and muscle damage. Kondziela's inverted test was used to assess muscle strength. An exploratory protein array was performed on joint tissue to identify relevant inflammatory pathways. Human monocytes pretreated with PD were stimulated with CPP crystals. The use of specific inhibitors was instrumental in demonstrating their anti-inflammatory effects and assessing the role of SIRT1. The chemotaxis assay was performed to test the effect of PD and J-113863 on PBMCs migration in response to plasma and synovial fluids. Cytokine levels were measured by ELISA.

Results

CPP crystals injection resulted in swelling, leukocyte infiltration, loss of synovial membrane structure homogeneity. Mice pretreated with PD showed reduced ankle swelling and this was associated with very limited inflammatory damage. Regarding the effect on gastrocnemius muscle, crystals induced leukocyte infiltration and edema. PD and colchicine treatment reduced muscle damage and preserved musculoskeletal structure in mice. The cytokine array revealed the activation of various inflammatory pathways after CPP injection and PD was shown to influence leukocyte migration, angiogenesis and inflammation. In vitro, PD reduced inflammatory cytokines, chemokines and VEGF levels. CCR-1 inhibition was effective in reducing pro-inflammatory mediator levels in CPP treated monocytes and in reducing PBMCs migration. The anti-inflammatory action of PD also involved SIRT-1 activation, and its inhibition reverted the beneficial effects of PD. Finally, PD reduced the PBMCs migration in response to synovial fluids.

Conclusion

PD effectively prevents inflammatory responses to CPP crystals in mice, preserving both articular and muscular structures. Its anti-inflammatory effects are primarily mediated through pathways regulating leukocyte migration and the suppression of pro-inflammatory mediators.

Association Between Vascular Calcifications on Joint Radiographs and Calcium Pyrophosphate Crystal Arthritis: A Medical Records Review Study

OBJECTIVE

Previous studies have shown an association between chondrocalcinosis (CC) and vascular calcifications (VCs). This study aimed to investigate the association of VCs detected on joint radiographs (XRs) of older patients diagnosed with calcium pyrophosphate (CPP) arthritis compared with a control group with osteoarthritis (OA).

METHODS

A medical records review study of joint radiographs (knee and wrist) was conducted. CPP crystal arthritis was diagnosed based on at least 1 documented episode of arthritis with synovial fluid analysis positive for CPP crystals or imaging showing CC at 1 or more sites, with no alternative inflammatory arthritis diagnosis. The control group comprised patients with OA and no CC, matched 1:1 for age and sex. All participants were over 60 years of age. XRs were reviewed for CC, OA, and VCs at the affected joint by 2 independent observers.

RESULTS

A total of 98 patients were enrolled in both the CPP arthritis group and the OA group. VCs adjacent to the affected joint were detected in 69 patients of the CPP group and 19 patients of the control group (70.4% vs 19.4%, p < 0.001). Among patients aged 60 to 80 years, the presence of VCs on XRs was highly indicative of CPP, demonstrating a specificity of 89.2% (95% confidence interval: 79.1%-95.6%). In the CPP group, patients with VCs had a significantly higher prevalence of cardiovascular (CV) comorbidities.

CONCLUSIONS

The detection of VCs on XRs was strongly associated with CPP crystal arthritis. The presence of VCs may further serve as a biomarker for an increased burden of CV comorbidities.

Imaging and management of calcium pyrophosphate deposition disease

The radiological manifestations of calcium pyrophosphate deposition (CPPD) revolve around two main axes: the asymptomatic form and CPPD disease. The latter is a consequence of an immune response to calcium phosphate crystals. Chondrocalcinosis is broadly considered the radiographic manifestation of CPPD regardless of whether it is asymptomatic or associated with inflammatory arthritis. CPPD is associated with osteoarthritis although the direction of such association is still unclear. Apart from the detection of CPP crystals in synovial fluid, imaging (mainly conventional radiography and increasingly ultrasound) plays a central role in the diagnosis of CPPD disease. Recently, CT has been added as a diagnostic tool, especially in deep anatomic locations such as crowned dens. To date, no treatment is effective in dissolving CPP crystals. For now, the focus of current treatment strategies remains inflammation control. Our aim is to review the epidemiology, pathogenesis, and clinical and imaging manifestations of asymptomatic and symptomatic CPPD. We will also discuss recent consensus definitions and classifications of CPPD disease.

Crowned Dens Syndrome Presenting as Failure to Thrive in a Patient With Moderate Cognitive Impairment

Crowned dens syndrome (CDS) is a rare condition characterized by the deposition of calcium pyrophosphate (CPP) or hydroxyapatite crystals around the odontoid process of the C2 vertebra, often presenting with acute neck pain, reduced cervical mobility, and systemic inflammatory response. This case describes a 68-year-old male patient with a history of type 2 diabetes, hypertension, and benign prostatic hyperplasia who presented with generalized weakness and failure to thrive. This atypical presentation initially masked symptoms of CDS, delaying the diagnosis until the patient developed acute neck pain and stiffness, prompting further imaging. CT imaging revealed calcifications around the odontoid process, confirming the diagnosis of CDS. Given the severity of the symptoms, corticosteroids were administered, resulting in significant clinical improvement. This case highlights the importance of considering CDS in the differential diagnosis of older patients presenting with systemic inflammatory symptoms and unexplained neck pain, particularly when initial workups are inconclusive.

Coronary artery calcium and atherosclerotic cardiovascular disease risk scores in patients with calcium pyrophosphate deposition disease

OBJECTIVE

Calcium pyrophosphate deposition (CPPD) disease is associated with an increased risk for cardiovascular (CV) events. We examined the atherosclerotic burden by coronary artery calcium scores (Agatston score) and compared 10-year atherosclerotic CV (ASCVD) risk scores in patients with vs without chondrocalcinosis, a radiographic marker of CPPD.

METHODS

We performed a cross-sectional analysis at an academic medical center, 1991-2022. Among all patients with an Agatston score in routine care, we defined a cohort with chondrocalcinosis detected before the coronary artery calcium scan. Comparators without chondrocalcinosis were matched 2:1 on age and sex-the primary analysis excluded statin users. We compared Agatston scores between the chondrocalcinosis cohort and comparators. We also tested for differences between cohorts in 10-year ASCVD risk score frequencies (low, borderline/intermediate, or high).

RESULTS

756 patients with chondrocalcinosis were matched to 1554 comparators (mean age 68 years, 53% female). CV risk factor burden was high in both cohorts, and statin use was infrequent. The unadjusted Agatston score was non-significantly higher in the chondrocalcinosis cohort (mean 359.1, SD 737.9) than in matched comparators (mean 297.1, SD 644.9) (p= 0.08). High 10-year ASCVD risk scores were significantly more common in the chondrocalcinosis cohort than comparators (p< 0.01).

CONCLUSION

Coronary atherosclerosis burden by CAC was not significantly different between patients with chondrocalcinosis and matched comparators, though 10-year ASCVD risk scores were higher in the chondrocalcinosis cohort, suggesting that factors beyond coronary artery calcification contribute to the increased CV event rate in patients with CPPD disease.

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.

Concurrent Post-Zoster Cutaneous Vasculitis and Acute Calcium Pyrophosphate Deposition Disease (CPPD) in an Elderly Patient: A Case Report

Varicella-zoster virus (VZV) can lead to rare complications such as cutaneous vasculitis. We present a unique case of post-zoster cutaneous vasculitis in an 82-year-old male, occurring alongside acute calcium pyrophosphate deposition disease (CPPD), a previously undocumented association. The patient initially presented with a painful zoster rash and hand swelling, treated with oral acyclovir. Persistent swelling led to a diagnosis of CPPD in the wrist, managed with prednisone and colchicine. A biopsy of purplish discoloration at the zoster site confirmed vasculitis, which resolved after treatment. This case underscores the importance of recognizing post-zoster vasculitis, even in immunocompetent individuals, and suggests a potential link with CPPD that warrants further investigation.

Crystal-induced arthritis in prosthetic joints: a systematic review of clinical features, diagnosis, management, and outcomes

BACKGROUND

To summarize clinical presentations, baseline characteristics, diagnosis, treatment, and treatment outcomes through a systematic review of cases of crystal-induced arthritis in prosthetic joints in the literature.

METHODS

A systematic review of case reports and case series was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search was performed through PubMed/MEDLINE, Google Scholar, Embase, Cumulative Index to Nursing & Allied Health, and Web of Science. We identified case reports/case series in English of adult patients presenting with crystal-induced arthritis (gout, calcium pyrophosphate deposition disease) in prosthetic joints. Articles that met the inclusion criteria were utilized for qualitative data synthesis.

RESULTS

We found 44 cases of crystal-induced arthritis in prosthetic joints from 1984 to 2021. Crystal-induced arthritis in periprosthetic joints most frequently affects patients who had knee arthroplasty and most often presents as monoarticular arthritis that is usually acute in onset. However, several cases in the literature involved patients who had bilateral knee replacements and presented with a concurrent flare of gout or calcium pyrophosphate deposition disease in bilateral knees. Patients with crystal-induced arthritis in prosthetic joints show elevated white blood cell counts with neutrophil predominance and respond favorably to anti-inflammatory treatments, usually within one week. In many cases, crystal-induced arthritis was challenging to differentiate from prosthetic joint infection, with approximately one-third of patients undergoing surgical intervention and 35% receiving antibiotic treatment.

CONCLUSION

Crystal-induced arthritis in prosthetic joints can mimic prosthetic joint infections and should always be considered in the differential diagnoses of joint pain in prosthetic joints. We present the first systematic review of crystal-induced arthritis in prosthetic joints to increase awareness of the diagnosis and proper management.