Chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO)

Chronic Recurrent Multifocal Osteomyelitis (CRMO) and Juvenile Spondyloarthritis (JSpA): To What Extent Are They Related?

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory disease occurring mainly in the pediatric age group (before 16 years) and generally presents as a separate entity. Synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome combines osteoarticular and cutaneous involvement, similar to CRMO, and falls into the spectrum of spondyloarthritis (SpA). The fact that a patient can progress from one disease to another raises the question of whether CRMO, like SAPHO, could fall within the spectrum of SpA, ranging from a predominantly osteoarticular form to an enthesitic form with more or less marked skin involvement. In this review, we set out to discuss this hypothesis by highlighting the differences and similarities between CRMO and juvenile SpA in clinical, radiological and pathophysiological aspects. A common hypothesis could potentially consider intestinal dysbiosis as the origin of these different inflammatory diseases. Interindividual factors such as gender, environment, genetics and/or epigenetic background could act as combined disease modifiers. This is why we suggest that pathophysiology, rather than clinical phenotype, be used to reclassify these diseases.

Chronic recurrent multifocal osteomyelitis with a comprehensive approach to differential diagnosis of paediatric skull pain

A girl in middle childhood was referred to rheumatology with a 1-month history of progressive skull pain, preceded by fleeting musculoskeletal symptoms. Apart from a scaly rash on her scalp, she was well, with moderately elevated inflammatory markers. Skull imaging (radiographs, CT and MRI) revealed osteolytic lesions, soft tissue swelling and pachymeningeal enhancement at frontal and temporal convexities. Langerhans cell histiocytosis, bone infection/inflammation or malignancy was considered. Skin and bone biopsies eventually ruled out mimicking diseases and confirmed the diagnosis of chronic recurrent multifocal osteomyelitis (CRMO). She was treated with intravenous pamidronate (IVPAM) for 9 months, with rapid resolution of pain and gradual resolution of bony abnormalities. She remains in remission at 15-month follow-up. While CRMO can affect any bone, skull involvement is extremely rare, with a broad differential diagnosis. We recommend bone biopsy to confirm skull CRMO. The patient achieved excellent clinical and radiological response to IVPAM.

Image-guided percutaneous bone biopsy for pediatric osteomyelitis: correlating MRI findings, tissue pathology and culture, and effect on clinical management

Bone biopsy remains the gold standard for diagnosis of osteomyelitis while MRI results in a radiologic diagnosis that generally precedes biopsy. This study's purpose is to examine the diagnostic yield and effect of biopsy results on clinical management in children with suspected osteomyelitis and positive MRI findings. A retrospective review was performed at a tertiary care children's hospital. Search of the EMR and radiology PACS identified patients below 18 years who underwent bone biopsy with interventional radiology for osteomyelitis and had positive MRI findings for osteomyelitis prior to biopsy. Data was collected on patient demographics, MRI findings, biopsy procedural details, tissue culture, histopathology results, and clinical management before and after biopsy. Changes in management were categorized as antibiotic type/quantity, duration, or diagnosis. A total of 82 biopsies in 79 patients with suspicion for osteomyelitis and positive MRIs prior to biopsy were performed over 5 years from 2014 to 2019. All biopsies were successful and sent for tissue culture. 22/82 biopsies (27%) yielded positive cultures. Of those with tissue cultures, 16/22 (72%) resulted in change in clinical management. Of all biopsies, 18/82 (22%) resulted in a change in management (15 antibiotic, 1 duration, 2 diagnosis). The 2 changes in diagnosis included one biopsy done which was positive for cancer and a second which was found to not demonstrate osteomyelitis on histology. In the pediatric population, bone biopsy is a reasonably low morbidity procedure. However, there is a relatively low rate of positive tissue cultures even with MRI findings suspicious for osteomyelitis. Approximately 1 in 5 biopsies resulted in a change in clinical management, mostly in antibiotic selection. Bone biopsy may have a higher clinical impact in pre-specified circumstances.

Molecular interactions of adaptor protein PSTPIP2 control neutrophil-mediated responses leading to autoinflammation

Introduction

Autoinflammatory diseases are characterized by dysregulation of innate immune system leading to spontaneous sterile inflammation. One of the well-established animal models of this group of disorders is the mouse strain Pstpip2^cmo . In this strain, the loss of adaptor protein PSTPIP2 leads to the autoinflammatory disease chronic multifocal osteomyelitis. It is manifested by sterile inflammation of the bones and surrounding soft tissues of the hind limbs and tail. The disease development is propelled by elevated production of IL-1β and reactive oxygen species by neutrophil granulocytes. However, the molecular mechanisms linking PSTPIP2 and these pathways have not been established. Candidate proteins potentially involved in these mechanisms include PSTPIP2 binding partners, PEST family phosphatases (PEST-PTPs) and phosphoinositide phosphatase SHIP1.

Methods

To address the role of these proteins in PSTPIP2-mediated control of inflammation, we have generated mouse strains in which PEST-PTP or SHIP1 binding sites in PSTPIP2 have been disrupted. In these mouse strains, we followed disease symptoms and various inflammation markers.

Results

Our data show that mutation of the PEST-PTP binding site causes symptomatic disease, whereas mice lacking the SHIP1 interaction site remain asymptomatic. Importantly, both binding partners of PSTPIP2 contribute equally to the control of IL-1β production, while PEST-PTPs have a dominant role in the regulation of reactive oxygen species. In addition, the interaction of PEST-PTPs with PSTPIP2 regulates the production of the chemokine CXCL2 by neutrophils. Its secretion likely creates a positive feedback loop that drives neutrophil recruitment to the affected tissues.

Conclusions

We demonstrate that PSTPIP2-bound PEST-PTPs and SHIP1 together control the IL-1β pathway. In addition, PEST-PTPs have unique roles in the control of reactive oxygen species and chemokine production, which in the absence of PEST-PTP binding to PSTPIP2 shift the balance towards symptomatic disease.

Research Status and Hotspots of Chronic Osteomyelitis: A Bibliometric and Visualized Analysis

OBJECTIVE

The treatment of chronic osteomyelitis (COM) is extremely challenging for physicians and patients. It is of great significance to explore the research status, development trend and future research hotspots in the field of COM to promote the development of this field. This study is aimed to explore the global research status of COM and predict its future research hotspots based on bibliometric and visualized analysis.

METHODS

Web of Science core collection database was used to search the related literature of COM from 1994 to 2020. All data were imported into Microsoft Excel 2019 for collation. Additionally, the literature quality of countries, authors, journals, and institutions is evaluated. The VOS viewer software was used for conducting co-analysis, co-citation analysis, and keyword co-occurrence analysis of literature to analyze the global status and predict the future hotspots of the COM field.

RESULTS

A total of 726 articles were retrieved in this study. The number of global publications shows a trend of wave growth, but the increase is not significant. It is expected that the number of COM articles will remain at more than 50 per year in the next decade. The COM literature published in the United States (Publications = 160, H index = 37, average citations per item = 28.63) is of the highest quality. Girschick HJ (Publications = 16, H index = 14, average citations per item = 52.25) is the most contributed scholar in the field of COM. UNIV IOWA (Publications = 15, H index = 11, average citations per item = 57.27) and UNIV WURZBURG (Publications = 18, H index = 15, average citations per item = 47.5) are influential institutions in the field of COM. The results of co-occurrence analysis show that the field of COM can be roughly divided into the following five modules: COM surgical research, COM basic research, COM diagnosis-related research, chronic recurrent multifocal osteomyelitis (CRMO)-related research, risk factors of COM. Risk factors of COM are the module with the highest concentration of hot words.

CONCLUSION

COM-related research will continue to develop further in the next decade. The diagnosis research and risk factors of COM are the most popular research modules in recent years. Some controversial or troubled issues including the efficacy of perforator flap and fascia flap covering soft tissue, searching exclusive detection methods for the diagnosis of COM and bisphosphonates and biological agents in the treatment of CRMO may lead to the development of the COM field.

Diagnosis and Treatment Modalities for Osteomyelitis

Osteomyelitis is an infection-related inflammatory disease of the bones. Imaging and laboratory results are typically used to support a clinical diagnosis of osteomyelitis. Microbial cultures and bone biopsies provide conclusive diagnoses. The first imaging procedure that needs to be done is radiography, but its sensitivity is low in the early stages of the disease. The sensitivity of magnetic resonance imaging, both with and without contrast material, is higher for detecting areas of bone necrosis in advanced stages. Patients can be categorised for surgical treatment using a staging system based on major and minor risk factors. The main course of treatment should be antibiotics, which should be chosen depending on the findings of the culture and the characteristics of each patient. Bony debridement surgery is frequently required, and in high-risk patients or those with severe illness, additional surgical intervention can be necessary. Better outcomes are being attained in the treatment of this illness thanks to advancements in surgical treatment, antibiotic therapy, and the current resources for precise diagnosis and tailored responses to each kind of osteomyelitis. The classification systems that are most frequently employed, as well as the general epidemiological ideas, are presented together with the discussion of acute and chronic osteomyelitis. The key recommendations for diagnosing infections clinically, in the laboratory, and through imaging are covered, along with the recommendations for surgical and antibiotic procedures, and the function of hyperbaric oxygen as adjuvant therapy. We evaluate the osteomyelitis-related articles, summarise the most recent developments in diagnostic procedures and therapeutic regimens, evaluate the benefits and drawbacks of various diagnostic modalities and therapeutic approaches, and suggest areas of focus to help current diagnostic and therapeutic approaches.

Not all benign: disease course, complications, and sequalae of chronic recurrent multifocal osteomyelitis in children

PURPOSE OF REVIEW

Advances in pathogenesis of chronic recurrent multifocal osteomyelitis in children (CRMO) have shaped therapeutic strategies. The use of whole-body MRI (WBMRI) and improved awareness of CRMO has increased rates and timeliness of CRMO diagnoses. In this review, we highlight the findings from recently published CRMO cohorts and describe the course, complications, and long-term sequalae of CRMO. It is important for clinicians to be aware of the potential for long-term sequelae in order to optimize therapy and avoid complications.

RECENT FINDINGS

Despite recent advances in defining disease pathogenesis, children with CRMO continue to suffer from complications and deformities. Involvement of the spine can be asymptomatic and is not as rare as previously suggested. This can result in damaging outcomes, such as vertebral fractures and permanent deformities. A subset of patients has polycyclic disease course and some continue to have active disease for years and well into adulthood, with significant impacts on quality of life.

SUMMARY

These recent findings have considerable implication on clinical practice regarding diagnosis, treatment, and monitoring of the disease. Collectively, they support the need for continued monitoring of the disease and screening using comprehensive imaging, such as WBMRI.

Canakinumab treatment in a young girl with refractory chronic recurrent multifocal osteomyelitis associated with pyoderma gangrenosum

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is a bone inflammatory disorder characterized by osteolytic, usually multiple, symmetric lesions. Diagnosis is one of exclusion, and no standardized therapies are available. Presumed deregulation of the interleukin (IL)-1β axis, as observed in 2 monogenic autoinflammatory conditions such as Majeed syndrome (LPIN2 mutations) and deficiency of IL-1 receptor antagonist (IL1RN mutations) with CRMO-like bone involvement, suggests the blockade of IL-1 as potentially useful also in this condition, even if scarce data are available.

CASE PRESENTATION

We report the case of a 13-year-old girl affected by a multidrug-resistant and pyoderma gangrenosum-complicated CRMO treated with canakinumab, a human monoclonal antibody targeting IL-1β.

CONCLUSION

In this young patient pyoderma gangrenosum and CRMO showed a rapid and satisfactory response to canakinumab, although over time a decreased efficacy in controlling bone disease was observed.

Chronic recurrent multifocal osteomyelitis. A narrative and pictorial review

Chronic recurrent and multifocal osteomyelitis (CRMO) is a nonsporadic autoinflammatory disorder. Currently, it is diagnosed based on clinical, radiologic, pathological, and longitudinal data. Numerous aspects should be highlighted due to increased knowledge in imaging and immunology. We emphasize the use of whole-body MRI, which is a non-invasive diagnostic strategy. A literature review was carried out on longitudinal studies. Commonly, the mean age at diagnosis is 11 years, ranging between 3 and 17. The most common sites are the long bone metaphysis, particularly femoral and tibial metaphysis. In addition, the pelvis, spine, clavicle, and mandible may be involved. In long bones, the radiologic appearance can show typical structure, mixed lytic and sclerotic, sclerotic or lytic. It is frequently metaphyseal or juxta-physeal, with hyperostosis or periosteal thickening. The involvement of the vertebral skeleton is often multifocal. Therefore, whole-body MRI is essential in identifying subclinical lesions. CRMO is a polymorphic disorder in which whole-body MRI is beneficial to demonstrate subclinical edema. Vertebral collapse requires long-term monitoring.

TNF-inhibitors or bisphosphonates in chronic nonbacterial osteomyelitis? - Results of an international retrospective multicenter study

Chronic nonbacterial osteomyelitis (CNO) can cause significant morbidity, including bone pain and damage. In the absence of clinical trials, treatments include non-steroidal anti-inflammatory drugs, corticosteroids, TNF-inhibitors (TNFi) and/or bisphosphonates. In a retrospective chart review in the United Kingdom and Germany, we investigated response to TNFi and/or pamidronate. Ninety-one patients were included, receiving pamidronate (n = 47), TNFi (n = 22) or both sequentially (n = 22). Patients with fatigue [p = 0.003] and/or arthritis [p = 0.002] were more frequently treated with TNFi than pamidronate. Both therapies were associated with clinical remission at 6 months, and reduction of bone lesions on MRI at 12 months. While not reaching statistical significance, pamidronate resulted in faster resolution of MRI lesions. Fewer flares were observed with TNFi. Failure to respond to pamidronate was associated with female sex [p = 0.027], more lesions on MRI [p = 0.01] and higher CRP levels [p = 0.03]. Randomized clinical trials are needed to confirm observations and generate evidence.

MRI in the Diagnosis and Treatment Response Assessment of Chronic Nonbacterial Osteomyelitis in Children and Adolescents

PURPOSE OF REVIEW

To explain the central role of magnetic resonance imaging (MRI) in the diagnosis and follow-up of chronic nonbacterial osteomyelitis (CNO) in children and adolescents, centering on practical technical aspects and salient diagnostic features.

RECENT FINDINGS

In the absence of conclusive clinical features and widely accepted laboratory tests, including validated disease biomarkers, MRI (whether targeted or covering the entire body) currently plays an indispensable role in the diagnosis and therapy response assessment of CNO. Whole-body MRI, which is the reference imaging standard for CNO, can be limited to a short tau inversion recovery (STIR) coronal image set covering the entire body and a STIR sagittal set covering the spine, an approximately 30-min examination with no need for intravenous contrast or diffusion-weighted imaging. The hallmark of CNO is periphyseal (metaphyseal and/or epi-/apophyseal) osteitis, identified as bright foci on STIR, with or without inflammation of the adjacent periosteum and surrounding soft tissue. Response to bisphosphonate treatment for CNO has some unique MRI findings that should not be mistaken for residual or relapsing disease. Diagnostic features and treatment response characteristics of MRI in pediatric CNO are discussed, also describing the techniques used, pitfalls encountered, and differential diagnostic possibilities considered during daily practice.

When the limp has a dietary cause: A retrospective study on scurvy in a tertiary Italian pediatric hospital

The limping child frequently represents a diagnostic challenge. The differential diagnosis is broad and should include vitamin C deficiency. Scurvy, resulting from vitamin C deficiency, is the oldest-known nutritional disorder. Despite its rarity in developed countries, scurvy has been increasingly reported in recent years in pediatric patients, particularly those with autism or neurological disabilities. In the present retrospective study, we describe the clinical, laboratory, and radiological features of 8 patients diagnosed with scurvy in the Pediatrics Unit of Meyer Children's University Hospital, between January 2016 and December 2021. The majority (87%) were males, and the median age was 3.7 years. Half of the patients had comorbidities known to be risk factors for scurvy, while the remaining patients were previously healthy. All the children were admitted for musculoskeletal symptoms, ranging from lower limb pain (87%) to overt limping (87%). Mucocutaneous involvement was observed in 75% cases. Microcytic anemia and elevated inflammatory markers were common laboratory findings. Bone radiographs, performed on all patients, were often interpreted as normal at first, with osteopenia (62%) as the most frequent finding; notably, after re-examination, they were reported as consistent with scurvy in four patients. The most common magnetic resonance imaging findings were multifocal symmetrical increased signal on STIR sequence within metaphysis, with varying degrees of bone marrow enhancement, adjacent periosteal elevation and soft tissue swelling. Differential diagnosis was challenging and frequently required invasive diagnostic procedures like bone marrow biopsy, performed in the first three patients of our series. The median time frame between clinical onset and the final diagnosis was 35 days. Notably, the interval times between admission and diagnosis become progressively shorter during the study period, ranging from 44 to 2 days. Treatment with oral vitamin C led to improvement/resolution of symptoms in all cases. In conclusion, scurvy should be considered in the differential diagnosis in a limping child, performing a detailed dietary history and careful physical examination, looking for mucocutaneous lesions. A quick and correct diagnostic path avoids invasive diagnostic procedures and reduces the risk of long-term complications.

Chronic non-bacterial osteomyelitis in children: Outcomes, quality of life

BACKGROUND

Chronic non-bacterial osteomyelitis is a chronic sterile inflammatory bone condition. We aimed to describe patients' clinical and radiographic findings and to evaluate their response to therapy and their quality of life.

METHODS

This cross-sectional study included 18 patients from a single center in Turkey whose clinical, radiological features, and outcomes were reviewed retrospectively. The quality of the patients' lives after treatment was compared with healthy controls using the Pediatric Quality of Life Inventory 4.0.

RESULTS

The median age of disease onset was 12 years (IQR 10-14 years) and 11 (61.1%) patients were male. The median follow-up duration was 15 months (IQR 12-22 months). The persistent form of chronic non-bacterial osteomyelitis was the most common pattern in 15 (83.3%) patients and a recurrent pattern was defined in three (16.7%) patients. The lesions were multifocal in all patients and 15 (83.3%) patients had symmetric distribution in whole-body magnetic resonance imaging. The most common sites of arthritis were the knee and sacroiliac joints. Methotrexate was used in 16 (88.9%) patients as first-line therapy. However, some patients were unresponsive to the first-line therapy and needed tumor necrosis factor-α inhibitors (55.6%) and bisphosphonates (16.7%). We observed remission in only four (22.2%) patients, and three (16.7%) patients were unresponsive. The patients had a significantly poorer quality of life than controls (P = 0.005).

CONCLUSIONS

Chronic non-bacterial osteomyelitis is an insidious disease that requires detailed analysis for diagnosis and whole-body magnetic resonance imaging is an effective tool for its diagnosis. Despite the advanced treatment, patients with chronic non-bacterial osteomyelitis have a poor quality of life.

Chronic Nonbacterial Osteomyelitis in Children

Chronic nonbacterial osteomyelitis (CNO) is an auto-inflammatory bone disorder with a wide spectrum of clinical manifestations, from unifocal to multifocal lesions. When it manifests with multifocal lesions, it is also referred to as chronic recurrent multifocal osteomyelitis (CRMO). CNO/CRMO can affect all age groups, with the pediatric population being the most common. Patients may present with systemic inflammation, but there is no pathognomonic laboratory finding. Magnetic resonance imaging (MRI) is the gold standard radiological tool for diagnosis. In the absence of validated diagnostic criteria, CNO/CRMO remains an exclusion diagnosis. Bone biopsy does not show a specific disease pattern, but it may be necessary in unifocal or atypical cases to differentiate it from malignancy or infection. First-line treatments are non-steroidal anti-inflammatory drugs (NSAIDs), while bisphosphonates or TNF-α blockers can be used in refractory cases. The disease course is unpredictable, and uncontrolled lesions can complicate with bone fractures and deformations, underlying the importance of long-term follow-up in these patients.

Mind the Localized Skeletal Pain: Chronic Recurrent Multifocal Osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare idiopathic aseptic inflammatory bone disorder affecting primarily children and adolescents characterized by an insidious onset of pain, swelling, and tenderness over the affected bones. The clinical signs and symptoms of CRMO are nonspecific, radiological and histopathological tests are essential for its diagnosis. We present a case of an 18-year-old young man who was diagnosed with CRMO by a combination of clinical data, laboratory results, radiological imaging, and bone biopsy. The patient started anti-inflammatory and immunosuppressant therapy, and his lower extremity pain and swelling improved. This report highlights to investigate promptly in children and adolescents with chronic leg pain, to emphasize the importance of combined clinical, laboratory, and imaging tests for early identification, to have a greater understanding of the imaging appearance and increasing knowledge of this condition, which help shorten time to reach a diagnosis and prevent permanent osseous damage and long-term disabilities.