Sacroiliitis mimics: a case report and review of the literature

Imaging of Sacroiliac Joints

The central role of imaging in diagnosing disorders affecting the sacroiliac joints (SIJs) necessitates a comprehensive understanding of the advantages, limitations, and potential pitfalls of the imaging techniques that can be used. In this article, the anatomy and biomechanics of SIJs are exposed, outlining their unique features, particularly the division into anteroinferior cartilaginous and postero-superior ligamentous parts. Overall, the goal of this article is to offer a comprehensive understanding of imaging techniques, anatomic complexity, and diagnostic considerations relevant to SIJs disorders, facilitating accurate diagnosis and patient management in clinical practice and research.

MRI predictors of infectious etiology in patients with unilateral sacroiliitis

BACKGROUND

Unilateral presentation of sacroiliitis is a diagnostic dilemma, especially between infection and inflammatory sacroiliitis associated with spondyloarthritis, requiring an early and accurate diagnosis.

OBJECTIVE

To assess the utility of magnetic resonance imaging (MRI) in differentiating infective versus inflammatory etiology in unilateral sacroiliitis.

MATERIALS AND METHODS

Retrospective review of the MRI of 90 patients with unilateral sacroiliitis, having an established final diagnosis. MR images were evaluated for various bone and soft tissue changes using predefined criteria and analyzed using univariate and multivariate regression analysis.

RESULTS

Among the 90 patients, infective etiology was diagnosed in 66 (73.3%) and inflammatory etiology in 24 (26.7%). Large erosions, both iliac and sacral-sided edema, joint space involvement with effusion or synovitis, soft tissue edema, elevated ESR/CRP, and absence of capsulitis and enthesitis were associated with infection (p < .001). The independently differentiating variables favoring infection on multivariate analysis were-both iliac and sacral-sided edema (OR 4.79, 95% CI: 0.96-23.81, p = .05), large erosions (OR 17.96, 95% CI: 2.66-121.02, p = .003), and joint space involvement (OR 9.9, 95% CI: 1.36-72.06, p = .02). Exclusive features of infection were osteomyelitis, sequestra, abscesses, sinus tracts, large erosions, and multifocality. All infective cases had soft tissue edema, joint space involvement, elevated ESR, and no capsulitis.

CONCLUSION

MRI evaluation for the presence and pattern of bone and joint space involvement, soft tissue involvement, and careful attention to certain exclusive features will aid in differentiating infectious sacroiliitis from inflammatory sacroiliitis.

A rare case presentation of septic sacroiliitis caused by staphylococcus xylosus and complicated with abscess formation: A case report

Septic sacroiliitis is one of the infectious causes of sacroiliitis and it is seen rarely. In current literature, cases of septic sacroiliitis caused by several microorganisms have been reported so far. This case report presents the first case of septic sacroiliitis caused by Staphylococcus xylosus and also complicated with an abscess formation.

Comparison of sacroiliac CT findings in patients with and without ankylosing spondylitis aged over 50 years

Diagnosis of axial spondyloarthritis (axSpA) is nowadays commonly made with the help of pelvic radiography or magnetic resonance imaging (MRI). However, there is an important inter-observer variability in radiography, and MRI is subject to possible false positives and is not the best modality for studying structural lesions. Conversely, pelvic computed tomography (CT) has excellent specificity and appears to be more effective than radiography for the diagnosis of ankylosing spondylitis (AS). However, its findings in patients over 50 years of age have not yet been studied. The objectives of this study were to describe the CT characteristics of sacro-iliac joints (SIJ) and the presence of intra-articular gas in patients with AS aged over 50 years and to compare them with controls of the same age and sex. This two-center, cross-sectional, observational study was performed using the medical records of the rheumatology departments of two University Hospitals. We included patients with a clinical diagnosis of axSpA, who had both definite radiographic sacroiliitis according to the modified New York criteria and met the ASAS 2009 criteria for axSpA (that is, AS), and who had undergone any CT scan including the whole SIJ. Each patient was matched for age and sex to a control randomly selected on the Picture Archiving and Communication System (PACS), symptomatic or asymptomatic, and without spondyloarthritis. For each individual, CT scans were interpreted blindly by two independent rheumatologists and scored for joint space narrowing (JSN), erosions, sclerosis, intra-articular gas, and diffuse idiopathic skeletal hyperostosis (DISH). Ninety patients and 90 controls were included in the study. The rates of positive JSN, erosion, and sclerosis scores were higher in the AS group (91% vs. 21%, p < 0.0001; 31% vs. 2%, p < 0.0001; 27% vs. 13%, p = 0.03, respectively), but the rates of intra-articular gas and DISH were higher in the control group (24% vs. 68%, p < 0.0001; 7% vs. 33%, p < 0.0001, respectively). 58% of patients had complete bilateral ankylosis. A total of 83 (92.2%) patients had a CT scan considered positive for AS, compared with only seven controls (7.8%). Sclerosis and erosions were predominantly on the anterosuperior part and iliac side of the joint in controls and were more diffuse in patients with AS. CT findings in patients with AS over 50 years of age are mostly represented by changes in the joint space; patients with AS have more erosions and sclerosis changes, but less intra-articular gas than controls.

Axial Spondyloarthritis and Diagnostic Challenges: Over-diagnosis, Misdiagnosis, and Under-diagnosis

PURPOSE OF REVIEW

This article aims to review the challenges in axial spondyloarthritis diagnosis and identify the possible contributing factors.

RECENT FINDINGS

The inability to reach an accurate diagnosis in a timely fashion can lead to treatment delays and worse disease outcomes. The lack of validated diagnostic criteria and the misuse of the currently available classification criteria could be contributing. There is also significant inter-reader variability in interpreting images, and the radiologic definitions of axial spondyloarthritis continue to be re-defined to improve their positive predictive value. The role of inflammatory back pain features, serologic biomarkers, genetics, and their diagnostic contribution to axial spondyloarthritis continues to be investigated. There is still a significant amount of delay in the diagnosis of axial spondyloarthritis. Appreciating the factors that contribute to this delay is of utmost importance to close the gap. It is similarly important to recognize other conditions that may present with symptoms that mimic axial spondyloarthritis so that misdiagnosis and wrong treatment can be avoided.

Osteitis Condensans Ilii: A Case Series

Osteitis condensans ilii (OCI) is a rare self-limiting low back pain syndrome. It is an incidental imaging discovery around sacroiliac joints with distinctive sclerotic lesions. We present three case reports as a series. In the first case, a 38-year-old female presented with unresolved chronic low back pain for eight years. She had bilateral triangular sclerosis of the ilium abutting sacroiliac joints and other causes of back pain were ruled out. Non-operative management was successful. In the second case, a 38-year-old female presented with acute exacerbation of low back pain for one year. She suffered low back pain during her pregnancy and postpartum period 16 years ago and intermittently after that. Bilateral radiodensity around sacroiliac joints was noted in the radiograph and she had successful remission with non-operative management. In the third case, a 45-year-old female presented with chronic low back for six years. On radiographs, she had bilateral sclerotic lesions around sacroiliac joints and responded well to non-operative management. OCI is a benign, idiopathic cause of axial low back pain. It is a diagnosis of exclusion and the pelvic radiographs classically show areas of sclerosis in the ilium adjacent to sacroiliac joints bilaterally. Treatment for OCI is essentially non-operative.

Clinical Manifestations and Diagnosis of Axial Spondyloarthritis

BACKGROUND

Axial spondyloarthritis (axSpA) is a chronic, rheumatic disease characterized by inflammation of the sacroiliac joint, spine, and entheses. Axial spondyloarthritis affects up to 1.4% of adults in the United States and is associated with decreased quality of life, increased mortality, and substantial health care-related costs, imposing a high burden on patients, their caregivers, and society.

SUMMARY OF WORK

Diagnosing axSpA can be difficult. In this review, we seek to help rheumatologists in recognizing and diagnosing axSpA.

MAJOR CONCLUSIONS

A discussion of challenges associated with diagnosis is presented, including use and interpretation of imaging, reasons for diagnostic delays, differences in disease presentation by sex, and differential diagnoses of axSpA.

FUTURE RESEARCH DIRECTIONS

The early diagnosis of axSpA and advances in available therapeutic options have improved patient care and disease management, but delays in diagnosis and treatment remain common. Additional research and education are critical for recognizing diverse axSpA presentations and optimizing management early in the course of disease.

Non-typhoidal, Non-paratyphoidal Salmonella Species Causing Sacroiliitis and Pyomyositis in a Healthy 19-Year-Old Athlete

Salmonella is a gram-negative bacterium, subdivided into typhoidal and non-typhoidal Salmonella. It is usually caused by eating raw or undercooked meat, poultry, eggs, or egg products. The clinical manifestations of Salmonella infection can be divided into five syndromes: enterocolitis (food poisoning), enteric (typhoid) fever, bacteremia/septicemia, focal infection, and a chronic carrier state, which is usually asymptomatic. The most common clinical presentation is diarrhea. Salmonella osteomyelitis occurs most frequently in patients with sickle-cell disease; other risk factors include other hemoglobinopathies, immunocompromised status, and chronic Salmonella carrier state. The incidence of Salmonella osteomyelitis/septic arthritis in otherwise healthy individuals is rare. The duration of symptoms can range from a few months to several years, and multifocal involvement occurs in 15% of reported cases of Salmonella osteomyelitis. The symptoms of Salmonella osteomyelitis are pain and variable swelling of the affected limb; high temperatures are rarely noted. Our patient is a 19-year-old boy with no known past medical history who presented with severe right-sided sacroiliitis with extensive surrounding osteomyelitis on both sides of the sacroiliac joint with non-typhoidal, non-paratyphoidal Salmonella bacteremia.

Associations between sarcoidosis, autoimmune diseases, and autoantibodies: a single-center retrospective study in China

To describe the clinical manifestations, immunological features, and risk factors in patients with sarcoidosis complicated with autoimmune diseases (ADs) as well as determine the frequency of autoantibodies and possible correlation between autoantibodies and laboratory data. Patients with pathologically confirmed sarcoidosis at Beijing Chaoyang Hospital (China) between January 2017 and October 2020 were included. Age- and sex-matched patients who visited the rheumatology outpatient clinic without systemic or ADs were included as controls. Demographic, clinical, serological, and radiological data of sarcoidosis patients were recorded and analyzed. To exclude ADs, autoantibodies, such as antinuclear antibody, extractable nuclear antigen antibodies, and anti-cyclic citrullinated peptide antibody were assessed in controls. A total of 154 sarcoidosis patients (111 females; 72.1%) with a mean ± standard deviation age of 50.7 ± 10.3 years were included. Nineteen patients (12.3%) had ADs; Hashimoto's thyroiditis (n = 6) and Sjogren's syndrome (n = 4) were common. Age, globulin, immunoglobulin G, erythrocyte sedimentation rate (ESR), and C-reactive protein were significantly different between sarcoidosis patients with and without ADs. The ESR level might be a risk factor for sarcoidosis complicated with ADs (RR = 1.053; P = 0.018). Autoantibodies were detected in 29 patients (18.8%), and the frequency was significantly higher than that in controls (18.8% vs. 3%; P = 0.001). Sarcoidosis patients were more likely to have autoantibodies despite the absence of ADs (10.4% vs. 3%; P = 0.031). Age may be a risk factor for sarcoidosis patients presenting with autoantibodies (RR = 1.077; P = 0.042). An association was identified between ADs and sarcoidosis. The inflammatory indexes, such as ESR, IgG, and CRP, were significantly different between sarcoidosis patients with and without ADs. ESR might be a risk factor for the coexistence of ADs and sarcoidosis. Sarcoidosis patients were prone to being autoantibody-positive despite the absence of ADs, and age might be a risk factor for sarcoidosis presenting with autoantibodies.

Mimics of axial spondyloarthritis

PURPOSE OF REVIEW

Axial spondyloarthritis (AxSpA) is a distinct clinical entity with characteristic clinical and radiographic features; however, a multitude of other metabolic, infectious and inflammatory disorders mimic it both clinically and radiographically.

RECENT FINDINGS

We present in this review article recent updates about the various disease entities and conditions that may mimic AxSpA and how to differentiate among them. The sensitivity and specificity of MRI in diagnosing AxSpA has limitations and needs to be interpreted in the context of the clinical picture. Interestingly, some recent studies have highlighted that a relatively high prevalence of bone marrow edema on pelvic MRIs in healthy volunteers which could even be categorized as having a 'positive MRI' as defined by Assessment of Spondyloarthritis International Society. Another study revealed that a substantial proportion of patients with suspected sacroiliitis were more commonly diagnosed with diseases other than inflammatory sacroiliitis. On the basis of these reports, it is prudent to request MRIs in the appropriate clinical context and interpreted with caution taking into considerations the wide differential diagnosis of such MRI changes.

SUMMARY

Highlighting the clinical pearls that differentiate disorders suspected of having sacroiliitis will lead to earlier and correct diagnosis and management; however, one must always take into considerations the radiographic and MRI findings in addition to the clinical presentations in order to make the appropriate diagnosis.

Osteitis condensans ilii: current knowledge and diagnostic approach

Osteitis condensans ilii is a noninflammatory condition of an uncertain etiology, characterized by sclerotic bone lesions located mainly in the iliac region of the sacroiliac joints. In many patients, osteitis condensans ilii remains an incidental imaging finding; however, it has been associated with lower back pain and may mimic inflammatory rheumatic conditions such as axial spondyloarthritis. The diagnosis is based on the presence of the characteristic sclerotic lesions on radiographs and the exclusion of other conditions that are associated with back pain. Management is usually conservative with the use of physical therapy and analgesics, and it is associated with a favorable prognosis. Herein, we conducted a narrative literature review using the terms osteitis condensans ilii, and we identified case reports, case series, reviews, and original studies associated with the condition. The aim of this article is to raise the awareness of this underrecognized clinicoradiological condition and to enable the health-care providers to recognize clinical and radiological features that should raise suspicion of the osteitis condensans illi, and to describe the treatment options.

Management of Instability following Pyogenic Sacroiliitis: Technical Case Report

Background

Septic arthritis of the sacroiliac joint (SI-joint) is a rare and often delayed diagnosis. Management usually consists of intravenous antibiotics and debridement of infected tissue. However, very few reports consider the management of the secondary instability of the sacroiliac joint. Case Presentation. We report a case of a 16-year-old girl diagnosed with S. aureus pyogenic sacroiliitis who benefited from aggressive surgical debridement and primary arthrodesis for infection-related SI-joint instability in the acute infection phase.

Conclusion

Diagnosis of pyogenic sacroiliitis is often delayed. Destruction of the joint can lead to chronic pain and instability. In cases of obvious intraoperative instability, primary arthrodesis could be considered in young patients.

Imaging of sacroiliitis: Current status, limitations and pitfalls

The clinical need to diagnose sacroiliitis at an earlier stage has led to the sacroiliac joints being more frequently imaged, particularly with magnetic resonance imaging (MRI). This review outlines the imaging approach to sacroiliitis, emphasizing the imaging protocols, diagnostic criteria, limitations and potential mimics of MRI examination. The value of imaging-guided intervention in sacroiliac joint disease is also briefly outlined.

US National Health and Nutrition Examination Survey Arthritis Initiatives, Methodologies and Data

The US National Health and Nutrition Examination Survey (NHANES) has collected population-based, nationally representative examination, laboratory, and radiographic data for arthritis and musculoskeletal diseases for more than 50 years. The resulting body of data and publications are substantial, yet much data remain unpublished. This review provides a basic understanding of the design and capabilities of the NHANES survey, reviewing the major accomplishments in the area of arthritis and musculoskeletal diseases. Currently available US National Health and Nutrition Examination Survey arthritis-related datasets are identified. Guidelines for using these data, and opportunities for data analysis and designing future studies are presented.