P2RX7 gene variants associate with altered inflammasome assembly and reduced pyroptosis in chronic nonbacterial osteomyelitis (CNO).

Chronic nonbacterial osteomyelitis (CNO), an autoinflammatory bone disease primarily affecting children, can cause pain, hyperostosis and fractures, affecting quality-of-life and psychomotor development. This study investigated CNO-associated variants in P2RX7, encoding for the ATP-dependent trans-membrane K+ channel P2X7, and their effects on NLRP3 inflammasome assembly. Whole exome sequencing in two related transgenerational CNO patients, and target sequencing of P2RX7 in a large CNO cohort (N = 190) were conducted. Results were compared with publicly available datasets and regional controls (N = 1873). Findings were integrated with demographic and clinical data. Patient-derived monocytes and genetically modified THP-1 cells were used to investigate potassium flux, inflammasome assembly, pyroptosis, and cytokine release. Rare presumably damaging P2RX7 variants were identified in two related CNO patients. Targeted P2RX7 sequencing identified 62 CNO patients with rare variants (32.4%), 11 of which (5.8%) carried presumably damaging variants (MAF <1%, SIFT "deleterious", Polyphen "probably damaging", CADD >20). This compared to 83 of 1873 controls (4.4%), 36 with rare and presumably damaging variants (1.9%). Across the CNO cohort, rare variants unique to one (Median: 42 versus 3.7) or more (≤11 patients) participants were over-represented when compared to 190 randomly selected controls. Patients with rare damaging variants more frequently experienced gastrointestinal symptoms and lymphadenopathy while having less spinal, joint and skin involvement (psoriasis). Monocyte-derived macrophages from patients, and genetically modified THP-1-derived macrophages reconstituted with CNO-associated P2RX7 variants exhibited altered potassium flux, inflammasome assembly, IL-1ß and IL-18 release, and pyroptosis. Damaging P2RX7 variants occur in a small subset of CNO patients, and rare P2RX7 variants may represent a CNO risk factor. Observations argue for inflammasome inhibition and/or cytokine blockade and may allow future patient stratification and individualized care.

Neuropathic and Nociplastic Pain Profiles are Common in Adult Chronic Nonbacterial Osteitis (CNO).

Chronic nonbacterial osteitis (CNO) is a rare musculoskeletal disease causing chronic bone pain. It is known that chronic musculoskeletal pain may involve other mechanisms than nociceptive pain only. We investigate the prevalence of neuropathic and nociplastic pain in adult CNO and their association with clinical characteristics and treatment outcomes. Survey study among the Dutch adult CNO cohort (n = 84/195 participated), including PAIN-detect for neuropathic pain, and the Central Sensitization Inventory (CSI), Fibromyalgia Rapid Screening Tool (FiRST), and ACTTION-APS Pain Taxonomy (AAPT) for nociplastic pain. Clinical characteristics and CNO-related bone pain scores were compared between patients with exclusive nociceptive pain and those with nociceptive pain plus neuropathic and/or nociplastic pain (mixed pain). 31% (95% CI 21-41) of patients classified as likely having neuropathic pain according to PAIN-detect. 53% (41-64) of patients displayed central sensitization on CSI, 61% (50-72) screened positive for fibromyalgia on FiRST and 14% (7-23) of patients fulfilled the AAPT criteria, all indicative of nociplastic pain. Mixed pain was associated with longer diagnostic delay (mean difference 2.8 years, 95% CI 0.4-5.2, p = 0.023), lower educational level (72% versus 20%, p < 0.001), and opioid use (37% versus 13%, p = 0.036). Despite comparable disease severity and extent, patients with mixed pain reported significantly higher CNO-related bone pain scores. This study demonstrates the high prevalence of mixed pain in adult CNO, in which neuropathic and nociplastic pain exist alongside nociceptive inflammatory bone pain. Disease burden in CNO may extend beyond inflammatory activity, highlighting the need for a multifaceted management approach.

Preferential involvement of the pelvis and hips along with active sacroiliitis in chronic nonbacterial osteomyelitis: MRI of 97 patients from a single tertiary referral center.

OBJECTIVE: To present MRI distribution of active osteitis in a single tertiary referral center cohort of patients with chronic nonbacterial osteomyelitis (CNO). METHODS: Two musculoskeletal radiologists retrospectively reviewed MRI examinations of all patients with a final clinical diagnosis of CNO over 15 years. Sites of active osteitis at any time during the course of disease were divided into seven groups: (A) mandible, sternum, clavicles, or scapulas; (B) upper extremities; (C) subchondral sacrum and ilium immediately subjacent to sacroiliac joints (active osteitis denoting "active sacroiliitis" here); (D) pelvis and proximal 1/3 of femurs (excluding group C); (E) bones surrounding knees including distal 2/3 of femurs and 1/2 of proximal tibias and fibulas; (F) distal legs (including distal 1/2 of tibias and fibulas), ankles, or feet; (G) spine (excluding group C). Temporal changes of lesions in response to treatment (or other treatment-related changes such as pamidronate lines) were not within the scope of the study. RESULTS: Among 97 CNO patients (53 males [55%], 44 females; age at onset, mean ± SD, 8.5 ± 3.2 years; age at diagnosis, 10.3 ± 3.3 years), whole-body (WB) MRI was performed in 92%, mostly following an initial targeted MRI (94%). A total of 557 (346 targeted and 211 WB) MRIs were analyzed. Biopsy was obtained in 39 patients (40%), all consistent with CNO or featuring supporting findings. The most common locations for active osteitis were groups D (78%; 95% CI 69‒85%) and C (72%; 95% CI 62‒80%). CONCLUSION: Pelvis and hips were preferentially involved in this cohort of CNO patients along with a marked presence of active sacroiliitis. CLINICAL RELEVANCE STATEMENT: When suggestive findings of CNO are identified elsewhere in the body, the next targeted site of MRI should be the pelvis (entirely including sacroiliac joints) and hips, if whole-body MRI is not available or feasible. KEY POINTS: • Heavy reliance on MRI for diagnosis of CNO underscores the importance of suggestive distribution patterns. • Pelvis and hips are the most common (78%) sites of CNO involvement along with active sacroiliitis (72%). • Pelvis including sacroiliac joints and hips should be targeted on MRI when CNO is suspected.

Extra-osseous manifestations in chronic recurrent multifocal osteomyelitis: a retrospective study.

OBJECTIVES: Extra-osseous (EO) manifestations are poorly characterized in chronic recurrent multifocal osteomyelitis (CRMO). This study aimed to further define the frequency, characteristics and treatment of EO events in CRMO and whether different phenotypes can be distinguished and benefit from special management. METHODS: This multicentre retrospective study included CRMO patients followed in several paediatric rheumatology departments in France, between 2015 and 2022. EO manifestations were defined as skin lesions, gastrointestinal manifestations, arthritis, enthesitis, sacroiliitis, uveitis, vasculitis, and fever. At the last visit, the physician defined CRMO as active in the presence of clinical manifestations including both osseous and EO symptoms. RESULTS: We included 133 patients; 87 (65.4%) were girls; the median age at first symptoms was 9.0 years (interquartile range 7.0-10.0). EO manifestations were described in 90 (67.7%) patients, with a predominance of skin lesions (n = 51/90; 56.7%), followed by sacroiliitis (n = 38/90; 42.2%), enthesitis (n = 21/90; 23.3%), arthritis (n = 14/90, 15.6%) and gastrointestinal manifestations (n = 6/90, 6.7%). The use of non-steroidal anti-inflammatory drugs and bisphosphonates did not differ by presence or not of EO manifestations. Biologics were taken more frequently by patients with than without EO manifestations (p< 0.001); tumour necrosis factor inhibitors were used in 33 (36.7%) EO+ patients. Under this treatment, 18 (54.5%) patients achieved complete remission of osseous and EO manifestations. At the last visit, more EO-positive than EO-negative patients were on treatment (p= 0.009), with active disease in 58 (64.4%) patients. CONCLUSION: The analysis of EO manifestations in CRMO delineates 2 groups of patients in terms of severity and treatments used. Our study opens up new pathophysiological leads that may underlie the wide range of CRMO phenotypes.

Clinical characteristics and predictors for recurrence in chronic nonbacterial osteomyelitis: a retrospective multicenter analysis.

Background/aim: Chronic nonbacterial osteomyelitis (CNO) is a rare disease of unknown etiology and most commonly occurs during childhood or adolescence. The purpose of this study is to collect data on the clinical features, outcomes, and management of the disease and to identify the factors affecting recurrence. Materials and methods: This is a retrospective multicenter cross-sectional study of pediatric patients diagnosed with CNO. A total of 87 patients with a diagnosis of CNO followed for at least 6 months in 8 pediatric rheumatology centers across the country between January 2010 and December 2021 were included in this study. Results: The study included 87 patients (38 girls, 49 boys; median age: 12.5 years). The median follow-up time was 20 months (IQR: 8.5-40). The median time of diagnostic delay was 9.9 months (IQR: 3-24). Arthralgia and bone pain were the most common presenting symptoms. Multifocal involvement was detected in 86.2% of the cases and a recurrent course was reported in one-third of those included in the study. The most commonly involved bones were the femur and tibia. Vertebrae and clavicles were affected in 19.5% and 20.6% of cases, respectively. The erythrocyte sedimentation rate (ESR) values of 60.9% of the patients were above 20 mm/h and the C-reactive protein values of 44.8% were above 5 mg/L. The remission rate was 13.3% in patients using nonsteroidal antiinflammatory drugs and 75.0% in those using biological drugs. Vertebral and mandibular involvement and high ESR values at the time of diagnosis were associated with recurrence. Conclusion: In this multicenter study, CNO with vertebral and mandibular involvement and high ESR at diagnosis were associated with recurrence.

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.

Chronic nonbacterial osteomyelitis - clinical and magnetic resonance imaging features.

BACKGROUND: Chronic nonbacterial osteomyelitis (CNO) is a rare autoinflammatory bone disorder. Little information exists on the use of imaging techniques in CNO. MATERIALS AND METHODS: We retrospectively reviewed clinical and MRI findings in children diagnosed with CNO between 2012 and 2018. Criteria for CNO included unifocal or multifocal inflammatory bone lesions, symptom duration >6 weeks and exclusion of infections and malignancy. All children had an MRI (1.5 tesla) performed at the time of diagnosis; 68 of these examinations were whole-body MRIs including coronal short tau inversion recovery sequences, with additional sequences in equivocal cases. RESULTS: We included 75 children (26 boys, or 34.7%), with mean age 10.5 years (range 0-17 years) at diagnosis. Median time from disease onset to diagnosis was 4 months (range 1.5-72.0 months). Fifty-nine of the 75 (78.7%) children presented with pain, with or without swelling or fever, and 17 (22.7%) presented with back pain alone. Inflammatory markers were raised in 46/75 (61.3%) children. Fifty-four of 75 (72%) had a bone biopsy. Whole-body MRI revealed a median number of 6 involved sites (range 1-27). Five children (6.7%) had unifocal disease. The most commonly affected bones were femur in 46 (61.3%) children, tibia in 48 (64.0%), pelvis in 29 (38.7%) and spine in 20 (26.7%). Except for involvement of the fibula and spine, no statistically significant differences were seen according to gender. CONCLUSION: Nearly one-fourth of the children presented with isolated back pain, particularly girls. The most common sites of disease were the femur, tibia and pelvic bones. Increased inflammatory markers seem to predict the number of MRI sites involved.

Chronic nonbacterial osteomyelitis in children: a multicenter case series.

Chronic nonbacterial osteomyelitis (CNO) is a primary autoinflammatory bone disease that presents more frequently in children and is characterized by inflammatory bone lesions in the absence of an infectious etiology. There is little information of this disease in Latin America. The objective of the study was to evaluate demographic, clinical, laboratory, imaging, histopathology characteristics, and treatment responses of pediatric CNO patients. The clinical records of 19 patients with CNO diagnosed between 2007 and 2019 at three tertiary centers in Santiago, Chile were reviewed. The median age of onset was 10 years and 47% were female. Median delay in diagnosis was 12 months. All patients had a pattern of recurrent multifocal disease. 37% of patients had positive antinuclear antibodies and 16% HLA-B27 positivity. 21% of patients presented arthritis or other rheumatologic comorbidity, although no association with psoriasis, inflammatory bowel disease (IBD) or palmoplantar pustulosis (PPP) was observed. Eighteen patients received treatment with nonsteroidal anti-inflammatory drugs with partial response. Twelve patients received methotrexate, and half of them received steroids at the same time reaching remission in 50%. Of the five patients who received bisphosphonates, 60% achieved remission. All four patients who received adalimumab had comorbid arthritis and 75% achieved remission. In a series of Chilean children with CNO, all patients presented with multifocal lesions. Comorbid autoimmune diseases including arthritis were frequent, but no association was observed with psoriasis, IBD, or PPP.

[Chronic nonbacterial osteomyelitis : Imaging and differential diagnoses]. / Chronische nichtbakterielle Osteomyelitis : Bildgebung und Differenzialdiagnosen.

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disease in childhood and adolescence with a preference for the female gender. It is manifested with multiple osseous lesions, with a predilection for the metaphyseal end zones of the long bones of the lower extremities. These bone lesions usually occur multifocally, can recur and develop a different appearance depending on the bone structure affected. Patients present with a longer disease history, changing clinical symptoms and unspecific paraclinical signs. Magnetic resonance imaging (MRI) is the imaging of choice and particularly as a whole body examination can speed up the diagnosis and is an important component of follow-up controls. Differential diagnoses include numerous inflammatory, benign and malignant bone diseases. Therefore, it is essential to know the diagnosis of CNO and to take it into consideration in cases of an unclear inflammatory bone process in young patients.

Total clavicle reconstruction with free peroneal graft for the surgical management of chronic nonbacterial osteomyelitis of the clavicle: a case report.

BACKGROUND: Chronic nonbacterial osteomyelitis (CNO) is a rare chronic autoinflammatory syndrome affecting mainly children and young adults. The natural history of the disease is marked by recurrent pain as the mainstay of inflammatory outbreaks. Typical radiographic findings are osteosclerosis and hyperostosis of the medial clavicle, sternum and first rib. Compression of the brachial plexus is exceedingly rare and one of the few surgical indications. Literature on total clavicle reconstruction is scarce. While claviclectomy alone has been associated with fair functional and cosmetic outcomes, several reconstruction techniques with autograft, allograft or even cement ("Oklahoma prosthesis") have been reported with the aim of achieving better pain control, cosmetic outcome and protecting the brachial plexus and subclavian vessels. We herewith report a unique case of complicated CNO of the clavicle treated with total clavicle reconstruction using a free peroneal graft. CASE PRESENTATION: A 21-year-old female patient presented with CNO of her left clavicle, associated with recurrent, progressive and debilitating pain as well as limited range of motion. In recent years, she started complaining of paresthesia, weakness and pain radiating to her left arm during arm abduction. The clavicle diameter reached 6 cm on computed tomography, with direct compression of the brachial plexus and subclavian vessels. Following surgical biopsy for diagnosis confirmation, she further developed a chronic cutaneous fistula. Therefore, a two-stage total clavicle reconstruction using a vascularized peroneal graft stabilized by ligamentous reconstruction was performed. At two-year follow-up, complete pain relief and improvement of her left shoulder Constant-Murley score were observed, along with satisfactory cosmetic outcome. CONCLUSIONS: This case illustrates a rarely described complication of CNO with direct compression of the brachial plexus and subclavian vessels, and chronic cutaneous fistula. To our knowledge, there is no consensus regarding the optimal management of this rare condition in this context. Advantages and complications of clavicle reconstruction should be carefully discussed with patients due to limited evidence of superior clinical outcome and potential local and donor-site complications. While in our case the outcomes met the patient's satisfaction, it remains an isolated case and further reports are awaited to help surgeons and patients in their decision process.

Chronic nonbacterial osteomyelitis from a tertiary care referral center.

Chronic nonbacterial osteomyelitis (CNO) is a little known autoinflammatory bone disorder primarily affecting children and sometimes young adults. Diagnosis is often delayed due to its varied and nonspecific initial symptoms. Very few cases are reported from India. The aim of this report is to increase the awareness of this disease among physicians, orthopedic surgeons, and rheumatologists. Four male patients were diagnosed with CNO in the past 3 years. The age at onset varied from 9 to 23 years with a median diagnostic delay of 3.5 years. All patients presented with recurrent bony pain with or without localized swelling over the affected bones. Two patients had previously undergone open surgical procedures with bone biopsies and three patients had received at least one course of antibiotics. Two patients responded well to nonsteroidal anti-inflammatory drugs alone, one patient required a short course of glucocorticoids, and another patient required methotrexate to control disease activity. This case series includes males, onset at a relatively later age in most, and a longer diagnostic delay. Thus, in addition to children and adolescents, CNO should be suspected in young adults presenting with recurrent bony pain with or without localized swelling.

Serum biomarkers for the diagnosis and monitoring of chronic recurrent multifocal osteomyelitis (CRMO).

Chronic recurrent multifocal osteomyelitis (CRMO), the most severe form of chronic nonbacterial osteomyelitis, is an autoinflammatory bone disorder. A timely diagnosis and treatment initiation is complicated by the absence of widely accepted diagnostic criteria and an incomplete pathophysiological understanding. The aim of this study was to determine biomarkers for the diagnosis and follow-up of CRMO. Serum of 56 CRMO patients was collected at the time of diagnosis. As controls, sera from treatment-naïve age-matched patients with Crohn's disease (N = 62) or JIA (N = 28) as well as healthy individuals (N = 62) were collected. Multiplex analysis of 25 inflammation markers was performed. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests, canonical discriminant analysis, and mixed model variance analysis. Mostly monocyte-derived serum proteins were detectable and differed significantly between groups: IL-1RA, IL-2R, IL-6, IL-12, eotaxin, MCP-1, MIP-1b, RANTES. Multicomponent discriminant analysis allowed for the definition of algorithms differentiating between CRMO, Crohn's disease, and healthy controls. Persistently high levels of MCP-1, IL-12, sIL-2R correlated with incomplete remission in follow-up samples from CRMO patients. Discrimination algorithms allow differentiation between patients with CRMO or Crohn's disease, and healthy individuals. IL-12, MCP-1, and sIL-2R can act as markers for treatment response. Though confirmation of our findings in larger multiethnical cohorts is warranted, they may prove valuable to differentiate between otherwise healthy individuals or Crohn's disease patients with "bone pain" and CRMO patients. The elevation of mainly monocyte-derived pro-inflammatory serum proteins supports the hypothesis of pro-inflammatory monocyte/macrophages driving inflammation in CRMO.

Chronic nonbacterial osteomyelitis may be associated with renal disease and bisphosphonates are a good option for the majority of patients.

AIM: The aim of this Italian study was to describe the clinical features, treatment options and outcomes of a cohort of patients with chronic nonbacterial osteomyelitis (CNO). METHODS: This was a retrospective cohort study. Laboratory data, diagnostic imaging, histological features and clinical course are reported. RESULTS: We enrolled 47 patients diagnosed with CNO. Bone pain was the leading symptom, and multifocal disease was present in 87% of the patients. The majority of the bone lesions were located in the appendicular skeleton (58%). Extraosseous manifestations were present in 34% of the patients, and renal involvement was detected in four patients. Inflammatory indices were increased in 80%, and bone x-rays were negative in 15% of the patients. Nonsteroidal anti-inflammatory drugs (NSAIDs) were the first therapy for all patients, achieving clinical remission in 27%. A good response to NSAIDs was significantly associated with a better prognosis. Bisphosphonates were used in 26 patients, with remission in 73%. Only six patients (13%), all with spine involvement, developed sequelae. CONCLUSION: We found a possible association between CNO and renal disease. Bisphosphonates were more likely to lead to clinical remission when NSAIDs and corticosteroids had failed. Vertebral localisation was the only risk factor for potential sequelae.

Skull involvement in a pediatric case of chronic recurrent multifocal osteomyelitis.

An 11-year-old boy was diagnosed with chronic recurrent multifocal osteomyelitis (CRMO) and presented with right sacro-femoral and occipital lesions. Initially, a tumor was suspected. However, the bone biopsy showed osteomyelitis with a negative bacterial culture. Bone scintigraphy revealed inflammatory changes on multiple bone lesions. The slight elevation in inflammatory markers such as C-reactive protein was of little clinical value. He was diagnosed with CRMO by sacral biopsy, and the clinical course progressed, with the presence of a new occipital lesion observed after the 1-year follow-up. The administration of non-steroidal anti-inflammatory drugs successfully improved his clinical symptoms. The presence of a skull lesion in the occipital bone of a pediatric patient with CRMO has not been previously reported.

Simultaneous onset of chronic nonbacterial osteomyelitis in siblings.

Chronic nonbacterial osteomyelitis (CNO) is an uncommon autoinflammatory disorder. Significant effort has recently been spent to better define and treat this disorder including development of consensus treatment protocols, validate disease activity tools, and refining classification criteria. However, the underlying immunopathogenesis of the disease remains elusive. In this report, we describe the simultaneous onset of CNO in siblings. A pathogenic gene mutation was not identified, and these sisters lacked a similar biomarker profile. This report highlights that if a genetic predisposition for CNO exists, it may be related to complex polygenic or multifactorial mechanisms of disease evolution.

Musculoskeletal symptoms and their impact on health-related quality of life in chronic nonbacterial osteomyelitis patients.

INTRODUCTION: Chronic non-bacterial osteomyelitis (CNO) is a rare, non-infection- related inflammatory disorder that affects children and teens. Clinical manifestations of CNO range widely from moderate, time-limited, monofocal inflammation of the bone to extreme multifocal or chronically active inflammation of the bone. OBJECTIVES: The main aim of this study was to explore the correlation between musculoskeletal (MSK) symptoms and health-related quality of life (HRQoL) in patients with CNO. METHODS: Children and adults with CNO and their parents were asked to answer a web-based survey. The survey consisted of multiple questions centered around demographic, clinical and therapeutic data, MSK discomfort form based on the Nordic MSK Questionnaire and HRQoL based on Pediatric Quality of Life Inventory-4 (PedsQL-4) and PedsQL rheumatology module. The inclusion criteria included diagnosis of CNO before the age of 18. Patients who had malignancies or any chronic rheumatic, MSK, neurological disease prior to CNO onset were excluded. RESULTS: There was a total of 68 participants, mostly females (66.2%), with median age 14 years and median disease duration 4.75 years. The median number of bones affected by CNO was 5 and ranged from 1 to 24 bones. Among the studied patients, 45 patients (66.2%) had MSK manifestations at the last month. The most commonly affected part was ankle and feet (26.5%). Regarding HRQoL, patients with MSK manifestations had lower scores than did patients without in PedsQL-4 (p < 0.001) including domains of physical functioning (p < 0.001), emotional functioning (p = 0.033), social functioning (p < 0.001) and school functioning (p = 0.007) in addition to lower scores in PedsQL rheumatology module (p < 0.001) including domains of pain and hurt (p < 0.001), daily activities (p < 0.001), treatment (p = 0.035), worry (p = 0.001) and communication (p < 0.001). CONCLUSION: MSK manifestations have a negative impact on HRQoL in CNO patients. So, early identification and treatment are highly recommended.

Chronic non-bacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO) with a focus on pamidronate therapy.

Chronic recurrent multifocal osteomyelitis (CRMO), also called chronic nonbacterial osteomyelitis (CNO) or nonbacterial osteomyelitis (NBO), is a rare autoinflammatory bone disease of unknown etiology. However, the number of patients properly diagnosed would increase with better knowledge of the disease. In this regard, whole-body magnetic resonance imaging (WB MRI) has been found to be a better predictor of active lesions than clinical examination. Importantly, the RINBO index (radiologic index for NBO) quantifies the involvement based on the WB MRI. Further, a chronic nonbacterial osteomyelitis MRI scoring (CROMRIS) has been developed as an online tool for assessing WB MRI. The therapy consists of non-steroidal anti-inflammatory drugs (NSAIDs), bisphosphonates (pamidronate, zoledronate, etc.) and other drugs, including biologics. Pamidronate is an appropriate and safe therapy. The first pilot prospective randomised controlled trial (RCT) on pamidronate vs. placebo was carried out in adults. No RCT has been done in children yet. Besides RCTs, there are a number of issues to be explored in future, i.e. predictors of therapy effect, optimal therapy duration, predictors of therapy discontinuation and evaluation of optimal therapy protocol. Recently, the CNO clinical disease activity score (CDAS) was constructed and validated but the classification criteria are still being developed. As collaboration on this rare disease is essential, a prospective Chronic Nonbacterial Osteomyelitis International Registry (CHOIR) was established to generate future comparative effectiveness research data.

Spinal Involvement in Patients with Chronic Non-Bacterial Osteomyelitis (CNO): An Analysis of Distinctive Imaging Features.

Spinal involvement by chronic non-bacterial osteomyelitis (CNO) has been increasingly reported in recent years, often being presented as a diagnostic dilemma requiring differential diagnosis with bacterial spondylodiscitis and/or neoplasia. This study was aimed at identifying the imaging features of CNO facilitating its differentiation from other spinal diseases. Two radiologists assessed the imaging studies of 45 patients (16 male and 29 female, aged from 6 to 75 years, 15 children) with CNO collected from 5 referential centers. Spinal lesions were found in 17 patients (2 children and 15 adults), most often in the thoracic spine. In children, the lesions involved short segments with a destruction of vertebral bodies. In adults, the main findings were prominent bone marrow edema and osteosclerosis, endplate irregularities, and ankylosing lesions extending over long segments; paraspinal inflammation was mild and abscesses were not observed. In both children and adults, the involvement of posterior elements (costovertebral and facet joints) emerged as an important discriminator between CNO and neoplasia/other inflammatory conditions. In conclusion, a careful inspection of imaging studies may help to reduce the number of biopsies performed in the diagnostic process of CNO.

Chronic Nonbacterial Osteomyelitis of the Jaw in a 3-Year-Old Girl.

Differential diagnosis of bacterial osteomyelitis (BOM) and chronic nonbacterial osteomyelitis (CNO) is challenging. Pediatric CNO can be diagnosed at around 10 years of age and when CNO cases involve only the jaw, it is difficult to make a diagnosis in a young child. A 3-year-old female developed CNO at the jaw alone. She presented with no fever, right jaw pain, mild trismus, and a preauricular facial swelling around the right mandible. Computed tomography (CT) revealed a hyperostotic right mandible, with osteolytic and sclerotic changes associated with periosteal reaction. At first, we suspected BOM and antibiotics were administered. Subsequently, CNO was diagnosed, and the patient received flurbiprofen (a nonsteroidal anti-inflammatory drug (NSAIDs)). Lack of a sufficient response led to successful treatment with a combination of oral alendronate and flurbiprofen. Physicians should be aware of CNO, a rare autoinflammatory noninfectious bone disease of unknown etiology, even in young children, although the disease mostly affects older children and adolescents.