Sacroiliitis in inflammatory bowel disease.

PURPOSE OF REVIEW: This review summarizes the recent evidence regarding the epidemiology of inflammatory bowel disease (IBD) associated sacroiliitis, including the prevalence, pathogenesis, role of imaging, and therapeutic challenges. RECENT FINDINGS: Sacroiliitis is an underappreciated musculoskeletal manifestation of IBD, a chronic inflammatory condition of the gut affecting the younger population. Untreated sacroiliitis can lead to joint destruction and chronic pain, further adding to morbidity in IBD patients. Recent publications suggest sacroiliitis can be detected on abdominal imaging obtained in IBD patients to study bowel disease, but only a small fraction of these patients were seen by rheumatologists. Early detection of IBD-associated sacroiliitis could be achieved by utilization of clinical screening tools in IBD clinics, careful examination of existing computed tomography and MRI studies, and timely referral to rheumatologist for further evaluation and treatment. Current treatment approaches for IBD and sacroiliitis include several targeted biologic therapies, but IBD-associated sacroiliitis has limited options, as these therapies may not overlap in both conditions. SUMMARY: With the advances in imaging, sacroiliitis is an increasingly recognized comorbidity in IBD patients. Future studies focusing on this unique patient population will expand our understanding of complex pathophysiology of IBD-associated sacroiliitis and lead to identification of novel targeted therapies for this condition.

Predictors of treatment failure of non-steroidal anti-inflammatory drugs in patients with axial spondyloarthritis with focus on haptoglobin, haptoglobin polymorphism and zonulin.

According to the Assessment of SpondyloArthritis International Society-European Alliance of Associations for Rheumatology (ASAS-EULAR) recommendations for the management of axial spondyloarthritis (axSpA), patients should undergo at least two courses of non-steroidal anti-inflammatory drugs (NSAIDs) therapy. In our study, we enrolled axSpA patients both at onset and in a flare who had already been treated with NSAIDs ineffectively. Subsequently, according to the recommendations, they received modified NSAID treatment as another attempt to the first-line drug therapy and were monitored from there. We aimed to identify risk factors for treatment failure after 4 weeks (Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score ≥ 4) especially amongst zonulin and haptoglobin concentrations, and haptoglobin polymorphism. Treatment failure was observed in 71% of patients, and the following variables were contributed for occurrence of this state: higher zonulin levels, ankylosing spondylitis, X-ray sacroiliitis, magnetic resonance imaging sacroiliitis, long duration of symptoms, high BASDAI, and high value of spinal pain intensity on visual analogue scale. In addition, the following positive correlations were found: haptoglobin concentration with C-reactive protein (r = 0.56; p = 0.0004), and erythrocyte sedimentation rate (r = 0.62; p < 0.0001), as well as between zonulin levels and white blood count (r = 0.5; p = 0.0003). The results of the study presented the identified factors related to the standard treatment failure in axSpA, amongst them zonulin levels. They might be applied to point out the patients for whom the search for a more appropriate method of treatment should be considered.

Comparing MRI and conventional radiography for the detection of structural changes indicative of axial spondyloarthritis in the ASAS cohort.

OBJECTIVES: To compare MRI and conventional radiography of SI joints for detection of structural lesions typical for axial spondyloarthritis (axSpA). METHODS: Adult patients from the Assessment of SpondyloArthritis international Society (ASAS) cohort with symptoms suggestive of axSpA and both SI joint MRI and radiographs available for central reading were included. Radiographs were evaluated by three readers according to the modified New York (mNY) criteria grading system. The presence of structural damage on radiographs was defined as fulfilment of the radiographic mNY criterion and, additionally, a lower threshold for sacroiliitis of at least grade 2 unilaterally. MRI scans were assessed for the presence of structural changes indicative of axSpA by seven readers. Diagnostic performance [sensitivity, specificity, positive and negative predictive values (PPV and NPV) and positive and negative likelihood ratios (LR+ and LR-)] of MRI and radiographs (vs rheumatologist's diagnosis of axSpA) were calculated. RESULTS: Overall, 183 patients were included and 135 (73.7%) were diagnosed with axSpA. Structural lesions indicative of axSpA on MRI had sensitivity 38.5%, specificity 91.7%, PPV 92.9%, NPV 34.6%, LR+ 4.62 and LR- 0.67. Sacroiliitis according to the mNY criteria had sensitivity 54.8%, specificity 70.8%, PPV 84.1%, NPV 35.8%, LR+ 1.88 and LR- 0.64. Radiographic sacroiliitis of at least grade 2 unilaterally had sensitivity 65.2%, specificity 50.0%, PPV 78.6%, NPV 33.8%, LR+ 1.30 and LR- 0.69. CONCLUSION: Structural lesions of the SI joint detected by MRI demonstrated better diagnostic performance and better interreader reliability compared with conventional radiography.

Sacroiliac joint MRI for diagnosis of ax-SpA: algorithm to improve the specificity of the current ASAS MRI criteria.

OBJECTIVE: To compare sacroiliac joint (SIJ) lesions on MRI in women with versus without axial spondyloarthritis (ax-SpA) and establish an algorithm to determine whether such lesions are due to ax-SpA. METHODS: This retrospective comparative study assessed bone marrow edema (BME), sclerosis, erosions, osteophytes, and ankylosis at the SIJ in two groups of women, one with and another without ax-SpA. Sensitivity and specificity were calculated for combinations/characteristics of lesions, using rheumatologists' assessment with assessment of spondyloarthritis international society (ASAS) criteria as the gold standard for diagnosis of ax-SpA. RESULTS: Compared to women without ax-SpA, women with ax-SpA had more BME (61% vs 17%, p < 0.001), sclerosis (40% vs 22%, p < 0.001), erosions (35% vs 5%, p < 0.001), and ankylosis (2% vs 0%, p = 0.007), but less osteophytes (5% vs 33%, p < 0.001). The ASAS MRI criteria yielded 59% sensitivity and 88% specificity, while a new algorithm achieved 56% sensitivity and 95% specificity using the following criteria: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ. CONCLUSIONS: We recommend the following pragmatic algorithm for MRI diagnosis of ax-SpA in women: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ. The false positive rate when using the new algorithm (3.3%) is less than half than when using the ASAS MRI criteria (7.7%); thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA. CLINICAL RELEVANCE STATEMENT: The developed algorithm has a false-positive rate that is less than half than when using the ASAS MRI criteria (3.3% vs 7.7%), thus its application in clinical practice could reduce overdiagnosis and prevent overtreatment of axial spondyloarthritis. KEY POINTS: • Compared to women without axial spondyloarthritis (ax-SpA), women with ax-SpA had a significantly higher prevalence of bone marrow edema (BME), sclerosis, erosions, and ankylosis, but a significantly lower prevalence of osteophytes. • A new algorithm for positive ax-SpA based on sacroiliac joint MRI was developed: no osteophytes at the sacroiliac joint (SIJ) and either (i) BME at the SIJ with at least one dimension ≥ 8 mm or (ii) at least one erosion at the SIJ. • We recommend this new algorithm for diagnosis of ax-SpA in women, as it has a significantly better specificity than the assessment of spondyloarthritis international society (ASAS) MRI criteria and less than half the false positive rate; thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA.

Clues for inflammatory diseases in the differential diagnosis of a child with sacroiliitis.

BACKGROUND: The purpose of this study was to compare the demographic, clinical and laboratory characteristics of patients with enthesitis-related arthritis (ERA), familial Mediterranean fever (FMF) and inflammatory bowel disease (IBD), which are inflammatory diseases that may develop sacroiliitis. Thus, it was aimed to reveal various findings that may indicate primary disease in patients with sacroiliitis. METHODS: Pediatric patients aged 6-18 years, who were being followed with a diagnosis of ERA (n = 62), FMF (n = 590), and IBD (n = 56) over the period 2013-2021 were included in the study. Sacroiliitis (n = 55) was diagnosed by magnetic resonance imaging of the sacroiliac joint, obtained from clinically suspected patients. RESULTS: Sacroiliitis was detected in 54.8% of ERA patients, 2.3% of FMF patients, and 12.5% of IBD patients. The mean follow-up period was 4.1 ± 2.8 years (10 months-8 years) for the entire study group. The most common MRI finding for sacroiliitis was bone marrow edema. Peripheral joint involvement (73.5%) and HLA B27 positivity (64.7%) was significantly higher in ERA patients, and ERA was diagnosed more frequently in patients presenting with sacroiliitis. Non-steroidal anti-inflammatory drugs (NSAIDs) were the first choice of treatment agent when sacroiliitis developed in all three patient groups. CONCLUSIONS: The clinical and laboratory findings of ERA, FMF and IBD can sometimes be intertwined or can even coexist. Treatment may differ depending on the disease associated with sacroiliitis, although NSAIDs may be used in the first-line treatment of all three diseases. Sacroiliitis patients with HLA B27 positivity and peripheral arthritis may need to be addressed as ERA.

Fetuin-A: A Novel Biomarker of Bone Damage in Early Axial Spondyloarthritis. Results of an Interim Analysis of the SPACE Study.

Our study aimed to evaluate the association between fetuin-A levels and the presence of radiographic sacroiliitis and syndesmophytes in patients with early axial spondyloarthritis (axSpA) and to identify potential predictors of radiographic damage in the sacroiliac joints (SIJs) after 24 months. Patients diagnosed with axSpA in the Italian cohort of the SpondyloArthritis-Caught-Early (SPACE) study were included. Physical examinations, laboratory tests (including fetuin-A), SIJ,+ and spinal X-rays and MRIs at T0 (diagnosis) and at T24 were considered. Radiographic damage in the SIJs was defined according to the modified New York criteria (mNY). Fifty-seven patients were included in this analysis (41.2% male, median (interquartile range), chronic back pain [CBP] duration of 12 (8-18) months). Fetuin-A levels were significantly lower in patients with radiographic sacroiliitis compared to those without at T0 (207.9 (181.7-215.9) vs. 239.9 (217.9-286.9), respectively, p < 0.001) and at T24 (207.6 (182.5-246.5) vs. 261.1 (210.2-286.6) µg/mL, p = 0.03). At T0, fetuin-A levels were significantly higher in non-smokers, in patients with heel enthesitis and in those with a family history of axSpA; fetuin-A levels at T24 were higher in females, in patients with higher ESR or CRP at T0 and in those with radiographic sacroiliitis at T0. Fetuin-A levels at T0 were independently negatively associated with the likelihood of radiographic sacroiliitis (OR = 0.9 per 10-unit increase (95% CI 0.8, 0.999), p = 0.048); but not with the presence of syndesmophytes. After adjustment for confounders, fetuin-A levels at T0 and T24 were also negatively associated with mNY at T0 (ß -0.5, p < 0.001) and at T24 (ß -0.3, p < 0.001), respectively. Among other variables at T0, fetuin-A levels did not achieve statistical significance in predicting mNY at T24. Fetuin-A levels were negatively associated with radiographic damage of the SIJs, but not of the spine, in early axSpA and after 2 years of follow-up. Our findings suggest that fetuin-A levels may serve as a biomarker to identify patients with a higher risk of developing severe disease and early structural damage.

The Juvenile Spondyloarthritis Disease Activity Index Is a Useful Tool in Enthesitis-Related Arthritis: Real-Life Data.

OBJECTIVE: To compare enthesitis-related arthritis (ERA) patients with active and inactive disease at 6 months and define baseline predictors for disease inactivity. In addition, to evaluate the demographic, clinical, and laboratory characteristics of ERA patients and to identify the real-life impact of the Juvenile Spondyloarthritis Disease Activity Index (JSpADA) in predicting active disease in ERA. METHODS: This medical record review study was conducted with 56 patients who were diagnosed with ERA at our clinic between June 2009 and June 2022. Demographic and clinical characteristics, laboratory parameters, treatment, and JSpADA were recorded. RESULTS: The patients were divided into 2 groups as active (n = 34) and inactive (n = 22) according to their disease activity at month six. Sex, age at diagnosis, number and type of affected joints, and presence of sacroiliitis were similar in both groups. There was no difference in baseline erythrocyte sedimentation rate, but there was a significant difference in erythrocyte sedimentation rate at the third month ( p = 0.52 and p = 0.018, respectively). The median JSpADA values at disease onset were 3.5 (interquartile range [IQR], 3.0-4.5) and 3.3 (IQR, 2.5-4.0) in the active and inactive groups, respectively ( p = 0.27). At the third month, the median JSpADA values were 1.5 (IQR, 0.5-2.1) in the active group and 0.5 (IQR, 0.5-1.5) in the inactive group ( p = 0.037). The cutoff value for JSpADA at the third month for active disease persisting at the month six was determined as 1 point (area under the curve, 0.662 ± 0.06; p = 0.042; 95% confidence interval, 0.51-0.80) by receiver operating characteristic curve analysis. CONCLUSION: In ERA patients, a persistently high JSpADA value at follow-up is a predictive factor for active disease at the sixth month.

Deep learning algorithms for magnetic resonance imaging of inflammatory sacroiliitis in axial spondyloarthritis.

OBJECTIVE: The aim of this study was to develop a deep learning algorithm for detection of active inflammatory sacroiliitis in short tau inversion recovery (STIR) sequence MRI. METHODS: A total of 326 participants with axial SpA, and 63 participants with non-specific back pain (NSBP) were recruited. STIR MRI of the SI joints was performed and clinical data were collected. Region of interests (ROIs) were drawn outlining bone marrow oedema, a reliable marker of active inflammation, which formed the ground truth masks from which 'fake-colour' images were derived. Both the original and fake-colour images were randomly allocated into either the training and validation dataset or the testing dataset. Attention U-net was used for the development of deep learning algorithms. As a comparison, an independent radiologist and rheumatologist, blinded to the ground truth masks, were tasked with identifying bone marrow oedema in the MRI scans. RESULTS: Inflammatory sacroiliitis was identified in 1398 MR images from 228 participants. No inflammation was found in 3944 MRI scans from 161 participants. The mean sensitivity of the algorithms derived from the original dataset and fake-colour image dataset were 0.86 (0.02) and 0.90 (0.01), respectively. The mean specificity of the algorithms derived from the original and the fake-colour image datasets were 0.92 (0.02) and 0.93 (0.01), respectively. The mean testing dice coefficients were 0.48 (0.27) for the original dataset and 0.51 (0.25) for the fake-colour image dataset. The area under the curve of the receiver operating characteristic (AUC-ROC) curve of the algorithms using the original dataset and the fake-colour image dataset were 0.92 and 0.96, respectively. The sensitivity and specificity of the algorithms were comparable with the interpretation by a radiologist, but outperformed that of the rheumatologist. CONCLUSION: An MRI deep learning algorithm was developed for detection of inflammatory sacroiliitis in axial SpA.

Quantification of bone marrow oedema and fat metaplasia in sacroiliac joints in spondyloarthritis patients using histographic magnetic resonance imaging analysis.

OBJECTIVES: To demonstrate a possible basis for a quantitative magnetic resonance imaging (MRI) approach that uses histographic analysis to determine bone marrow oedema (BME) and fat metaplasia at sacroiliac joints (SIJs) level in patients with axial spondyloarthritis (axSpA). METHODS: In this prospective, cross-sectional study, consecutive axSpA patients with inflammatory low back pain underwent 1.5-T MRI. MRI images were scored on a 4-point (0-3) scoring system both for BME and fat metaplasia by two radiologists. A region-of-interest based histographic quantitative analysis was used to assess MRI images. Using the area under the receiver operating characteristic curve (AUC-ROC) approach was tested the diagnostic accuracy of histographic analysis for detecting BME vs. BME and fat metaplasia on MRI images. RESULTS: 17 of the 43 patients (39.5%) included only had a BME lesion, while the remaining 26 patients (60.5%) had both BME and fat metaplasia at the SIJ level. Inter-rater agreement between readers was good (weighted kappa 0.643). On MRI images, BME and BME+fat metaplasia showed significant difference in histographic analysis (p<0.001), with an AUC-ROC of 0.898, and an optimal cut-off point of 311 at histographic analysis in the distinction of BME vs. fat metaplasia. CONCLUSIONS: Histographic analysis could represent a method for quantifying BME on MRI images of SIJs in patients with axSpA. This type analysis can provide important prognostic information and guide the choice of treatment in patients with sacroiliitis.

Clinical features and surgical management of tuberculous arthritis of the sacroiliac joint: a retrospective analysis of 33 patients.

BACKGROUND: We reviewed 3 different types of tuberculous sacroiliitis via anterior and posterior approaches to determine the efficacy and safety of this surgical approach by describing clinical presentation, imaging, and surgical treatment. METHODS: We reviewed 33 patients with 3 different types of severe tuberculous sacroiliitis, of which 16 patients with anterior iliac abscess underwent anterior debridement. 17 patients underwent posterior debridement. Among them, 5 patients with lumbar tuberculosis underwent lesion debridement through fenestration, joint fusion, and interbody fusion and internal fixation. The mean postoperative follow-up was 16.9 months (12-25 months).Erythrocyte sedimentation rate (ESR), visual analogue scale (VAS) and the Oswestry Disability Index (ODI) were used to judge the postoperative condition and functional recovery. RESULTS: All patients' hip, back and lower back pain symptoms were significantly relieved after surgical treatment. At 3 months after operation, the VAS and ODI scores of all patients decreased significantly. CONCLUSION: Surgical treatment of tuberculous sacroiliitis should be performed as soon as possible under the adjuvant chemotherapy of anti-tuberculosis drugs. According to the different characteristics of sacroiliac joint tuberculosis, appropriate surgical operations should be adopted according to our classification criteria.

[Answering epidemiologic rheumatologic questions by cooperation with the large population-based SHIP cohort-findings with relevance for the diagnosis of axial spondyloarthritis (axSpA)]. / Beantwortung epidemiologisch-rheumatologischer Fragestellungen durch Kooperation mit der bevölkerungsbasierten SHIP-Kohorte ­ Erkenntnisse für die Diagnostik der axialen Spondyloarthritis (axSpA).

This article presents how, based on the availability of new imaging methods and medications, objectives regarding the rheumatic disease axial spondyloarthritis (axSpA) have developed over the course of more than two decades into a rheumatologic research group. During recent years, cooperation with the Study of Health in Pomerania (SHIP) cohort has given rise to new fundamental aspects. This involved intensive cooperation between the Ruhr University Bochum (Rheumazentrum Ruhrgebiet) and the Greifswald University Hospital (Community Medicine research collective). The design of the SHIP cohort was published 10 years ago and the cohort approach presented in the Bundesgesundheitsblatt, which also described central methodologic questions in detail. In 2014, a cooperation project between the Ruhr Rheumatology Center/Ruhr University Bochum and the SHIP Department of Clinical and Epidemiologic Research (Klinisch-Epidemiologische Forschung, KEF; SHIP-KEF) was established, which has already resulted in publication of interesting results in high-ranking journals. In order to stress the potential of such corporations, important contents thereof are presented herein, with a focus on MRI and consideration of historical aspects.

[Spondyloarthritis in childhood and adulthood]. / Spondyloarthritiden im Kindes- und Erwachsenenalter.

Axial spondylarthritis in adulthood (SpAA) is frequently initially manifested as a sacroiliitis, whereas this not true for enthesitis-related arthritis (EAA), which begins in childhood and adolescence. Classically, EAA begins with peripheral arthritis and only a part transitions into a juvenile SpA (jSpA) or SpAA. The criteria used for classification of SpAA and EAA are currently being validated and revised. For the first time imaging is included for EAA. For both diseases nonsteroidal anti-inflammatory drugs (NSAID) are initially used therapeutically, followed by biologicals or synthetic targeted disease-modifying drugs in refractory courses. Steroids should be avoided in long-term treatment. For optimal transition and further care in adulthood, a close cooperation between internistic and pediatric rheumatologists is necessary.

Frequency of potential causes of lower back pain and incidental findings in patients with suspected sacroiliitis: retrospective analysis of 886 patients with negative sacroiliac MRI examination for sacroiliitis.

BACKGROUND: In a majority of patients with suspected sacroiliitis (SI) who underwent sacroiliac magnetic resonance imaging (MRI), imaging studies may be normal, may depict other causes for pain, or may show clinically irrelevant incidental findings. PURPOSE: To determine the prevalence of possible etiologies other than SI and frequency of incidental findings demonstrated on sacroiliac MRI examinations in a cohort of patients with lower back pain and suspected SI. MATERIAL AND METHODS: Sacroiliac MRI examinations of 1421 patients with suspected SI were retrospectively reviewed. In patients without SI findings, other potential causes for lower back pain and incidental findings were documented. RESULTS: SI was present in 535 of 1421 patients (37.6%). In 886 of the patients whose MRI studies were negative for SI, other possible causes for lower back pain or incidental findings were seen in 386 (43.5%). The most common musculoskeletal (MSK) finding was lumbosacral transitional vertebra (8.6%) followed by findings suggesting piriformis syndrome (4.2%), spondylosis (3.7%), and sacral insufficiency fractures (1.8%). The most common non-MSK findings were follicular cysts (15.3%) and uterine fibroids (4.9%). CONCLUSION: In patients with suspected SI but negative MRI examinations for SI, some other possible causes for lower back pain and several incidental findings can be seen on imaging. The presence of these findings may explain the patient's symptoms, and awareness of these conditions may be helpful in patient management and individualizing treatment.

Update on Juvenile Spondyloarthritis.

Spondyloarthritis (SpA) is a blanket term encompassing entities such as enthesitis-related arthritis, nonradiographic axial SpA, and ankylosing spondylitis. These diseases share many clinical features, including a predilection for inflammation of the entheses and the sacroiliac joints. The nomenclature is based on the evolution of the classification of the disease and the age of the patient. SpA has a prevalence of approximately 1% of the population of the United States, with 10% to 20% of patients experiencing the onset during childhood. Children with onset of arthritis before age 16 years are classified as having juvenile idiopathic arthritis. Children with enthesitis and/or sacroiliitis are further classified as belonging to the enthesitis-related arthritis subtype of juvenile idiopathic arthritis. The initial manifestations can be subtle and will usually include a peripheral pattern of arthritis and enthesitis. It may take several years for axial disease to develop in children. Except for an association with the human leukocyte antigen (HLA-B27) serotype, there are no laboratory markers for the disease, and the radiographic findings are often negative. A careful clinical evaluation for evidence of inflammation in the entheses and the joints and a search for comorbidities are required. Magnetic resonance imaging facilitates the early detection of sacroiliitis, an important feature that may be clinically silent. Because recent studies indicate that earlier introduction of therapy can help achieve better outcomes, rapid identification and treatment of children with SpA is essential.

MRI of the sacroiliac joints: what is and what is not sacroiliitis?

PURPOSE OF REVIEW: MRI has, as the only imaging modality, the ability to visualize both the inflammatory and destructive aspects of sacroiliitis and is a crucial element in the diagnosis and classification of axial spondyloarthritis (axSpA). However, the MRI appearance of several potential differential diagnoses may resemble axSpA sacroiliitis. RECENT FINDINGS: The appearances of sacroiliac joint (SIJ) MRIs of various diseased and healthy populations have recently been intensively studied. BME, the key requirement in the Assessment of Spondyloarthritis international Society (ASAS) definition of a 'MRI positive of sacroiliitis' may also be found in degenerative disease, athletes and healthy persons, and, particularly, postpartum women. Certain pattern of BME (high extent, large depth from articular surface, close relation to other lesion types) as well as the presence of structural lesions, particularly bone erosion, backfill or ankylosis increase the likelihood/specificity of being axSpA. Furthermore, old and novel MRI approaches to best distinguish the sacroiliitis of early axSpA from differential diagnoses have recently been tested and compared. SUMMARY: Significant new and clinically relevant knowledge has been gained, but further research is still needed to optimally distinguish what is and what isn't sacroiliitis.

Two pediatric cases of isotretinoin-induced sacroiliitis successfully treated with adalimumab.

Isotretinoin is widely used in severe acne. Isotretinoin has many side effects. Sacroiliitis is one of these side effects and has been rarely reported in the children. Herein, we present two children with isotretinoin-induced sacroiliitis resistant to anti-rheumatic drugs and successfully treated with adalimumab.

A patient with chronic sacroiliitis undiagnosed for three years after isotretinoin use.

BACKGROUND: Isotretinoin (ISO) is a synthetic vitamin A derivative which has been used for treatment-resistant acne vulgaris. Although most musculoskeletal side effects of ISO are common, including myalgia, arthralgia, and back pain, sacroiliitis is one of the uncommon side effects. ISO-induced sacroiliitis usually completely resolves within a few months by the cessation of the drug. CASE PRESENTATION: In this paper, we present a 26-year-old female patient with chronic sacroiliitis that was probably induced by ISO and not resolved by the discontinuation of the drug. CONCLUSION: In this patient, sacroiliitis was overlooked for three years. Therefore, ISO usage should be considered in the differential diagnosis of sacroiliitis and low back pain.

[Clinical and imaging characteristics of 110 patients with infectious sacroiliitis].

Objective: To investigate the clinical and imaging characteristics of infectious sacroiliitis. Methods: A total of 110 patients diagnosed with infectious sacroiliitis were retrospectively analyzed between 2008 and 2017.Clinical manifestations and therapeutic responses, laboratory tests such as HLA-B(27), erythrocyte sedimentation rate (ESR), C reactive protein (CRP), T cell spot test for tuberculosis infection(TB-SPOT), Brucella agglutination test ect., blood culture of pathogens, pathological findings as well as magnetic resonance imaging were all recorded and analyzed. Results: Among the 110 patients, the male to female ratio was 44 to 66 with an average age 15-58(29.4±10.8) years and the course of disease 0.3-60 (5.7±13.2) months. As to the pathogens, 71 cases were pyogenic, 24 cases with tuberculous sacroiliitis, and 15 cases were brucellosis infections. The majority of patients (97.3%) had unilateral sacroiliac joint involvement. Ten (9.1%) patients suffered infectious sacroiliac arthritis after delivery. Hip pain was the main clinical manifestation (83/110,75.5%) and fever as the second (77/110,70.0%). HLA-B(27) was positive in 11 patients (10.0%). Both ESR and CRP were elevated in the majority. There were 103 patients receiving sacroiliac joint puncture biopsy. Seven patients were diagnosed through blood culture or brucellosis agglutination test. Bone marrow edema and osteolytic lesions in magnetic resonance imaging (MRI) were more common in pyogenic or tuberculous sacroiliitis than in brucellosis infections. Conclusion: Infectious sacroiliitis should be differentiated from spondyloarthritis, which develops more in female patients, with short disease duration and fever, mostlynegative HLA-B(27). The majority patients present unilateral sacroiliitis. Active inflammatory lesions are usually beyond sacroiliac joints with osteolytic changes in MRI examinations.

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.

Pyogenic sacroiliitis: A rare complication of inflammatory bowel disease.

Although sacroiliitis is not uncommon in patients with inflammatory bowel diseases (IBD), bacterial infection of the sacroiliac joint is rare. The diagnosis is often delayed because of low clinical suspicion, a vague clinical picture and poorly defined localization of symptoms. We report a case of pyogenic sacroiliitis in a patient with Crohn's disease caused by Clostridia spp. and discuss key clinical components and protocol for the successful evaluation, diagnosis, and treatment of this uncommon illness.