Autoinflammatory bone diseases

A clinico-radiological review of chronic non-bacterial osteomyelitis in paediatrics, adolescents, and adults: demystifying a forgotten differential

Chronic non-bacterial osteomyelitis (CNO), also known as non-bacterial osteitis, is a chronic autoinflammatory disease of unknown aetiology that primarily occurs in the paediatric population, although rare cases of adult-onset disease also exist. CNO has non-specific clinical and radiological presentations, and the affected population often present with bone pain of insidious onset secondary to sterile bony inflammation that can be associated with swelling, focal tenderness, and warmth at the affected sites. The pattern of bony involvement appears to be dependent on the age of onset, with adults frequently having axial skeletal lesions and children and adolescents often being affected in the appendicular skeletal sites. CNO is a diagnosis of exclusion, and imaging is heavily relied on to identify and characterise the bony lesions in addition to exclude diseases that can mimic CNO. Magnetic resonance imaging is often the reference standard with biochemical and histopathological findings being complementary. Although combining imaging methods can be used to facilitate the diagnosis, a single technique could be adequate depending on the clinical picture. Given the relatively rare incidence of CNO, limited awareness of the disease among care providers, and its similarity in clinical and radiological presentation to various bony diseases, there are often long delays in diagnosis, with adults being unfavourably affected compared to paediatrics and adolescents. This review of CNO will describe the condition, overview its clinical presentation, highlight the radiological features, and emphasise clinical pearls that can aid in diagnosis and ruling out the mimics.

Pediatric Gnathic Bony and Mesenchymal Tumors

Evaluation of bone pathology within the head and neck region, particularly the gnathic bonesis is complex, demonstrating unique pathologic processes. In part, this variation is due to odontogenesis and the embryological cells that may be involved, which can contribute to disease development and histologic variability. As with any boney pathosis, the key is to have clinical correlation, particularly with radiographic imaging prior to establishing a definitive diagnosis. This review will cover those entities that have a predilection for the pediatric population, and while it is not all inclusive, it should serve as a foundation for the pathologist who is evaluating bony lesions involving the craniofacial skeleton.

Severe chronic non-bacterial osteomyelitis in combination with total MPO deficiency and responsiveness to TNFα inhibition

We describe a female patient suffering from severe chronic non-bacterial osteomyelitis (CNO) with systemic inflammation and advanced malnutrition and complete deficiency of myeloperoxidase (MPO). CNO is a rare autoinflammatory bone disorder associated with dysregulation of the innate immune system. MPO deficiency is a genetic disorder with partial or complete absence of the phagocyte peroxidase MPO. MPO deficiency has no established clinical phenotype but reports indicate increased susceptibility to infection and chronic inflammation. The patient's symptoms began at 10 years of age with pain in the thighs, systemic inflammation and malnutrition. She was diagnosed with CNO at 14 years of age. Treatment with nonsteroidal anti-inflammatory drugs, corticosteroids, bisphosphonates or IL1-receptor antagonists (anakinra) did not relieve the symptoms. However, the patient responded instantly and recovered from her clinical symptoms when treated with TNFα blockade (adalimumab). Three years after treatment initiation adalimumab was withdrawn, resulting in rapid symptom recurrence. When reintroducing adalimumab, the patient promptly responded and went into remission. In addition to clinical and laboratory profiles, neutrophil functions (reactive oxygen species, ROS; neutrophil extracellular traps, NETs; degranulation; apoptosis; elastase activity) were investigated both in a highly inflammatory state (without treatment) and in remission (on treatment). At diagnosis, neither IL1β, IL6, nor TNFα was significantly elevated in serum, but since TNFα blockade terminated the inflammatory symptoms, the disease was likely TNFα-driven. All neutrophil parameters were normal both during treatment and treatment withdrawal, except for MPO-dependent intracellular ROS- and NET formation. The role of total MPO deficiency for disease etiology and severity is discussed.

Inflammatory Diseases of the Eye, Bowel, and Bone in Children

Pediatric rheumatological diseases present with diverse manifestations affecting various tissues and organs. Though most childhood illnesses with immune dysregulation affect multiple organs or systems simultaneously or gradually, few inflammatory conditions affect certain organs as distinguished primary targets. Pediatric inflammatory diseases of the eye, bowel, and bone represent significant disorders with heterogeneous entities with varying pathophysiological basis like chronic inflammation, vasculitis, autoimmunity, and autoinflammation. Associations or complications of these diseases may remain obscure if their extensions are not explored specifically. Pediatric uveitis, non-uveitic inflammatory diseases, inflammatory bowel diseases, and autoinflammatory bone diseases are the important constituents of this cluster. The author concisely discusses these disorders in this review from pediatric rheumatological perspective. If untreated, these diseases may be organ-threatening. Outcomes are vastly different in undiagnosed patients and in timely diagnosed and treated patients. Lack of awareness and missed exploration of associated illnesses and complications may result in a missed diagnosis or inadequate symptomatic treatment. A multidisciplinary approach to diagnosis and treatment is desirable in these heterogeneous entities. Pediatricians must be aware of the immunological origin of organ-centered symptoms and signs. A proper understanding of molecular details of etiopathogenesis and significant advances in therapy have reduced the morbidity, disability, and mortality of such disorders.

Juvenile idiopathic arthritis with systemic onset with inflammatory bone lesions: two case reports of patients successfully treated with canakinumab and experience gained from literature

Non-bacterial osteomyelitis (NBO) is a rare chronic inflammatory bone disease related to immune system dysregulation. This disease belongs to a family of autoinflammatory diseases. It often coexists with other TNF-α-mediated immune-mediated diseases such as juvenile idiopathic arthritis (JIA) and inflammatory bowel diseases. Previously, interleukin-1-driven inflammation was described predominantly in monogenic cases of NBO, such as DIRA syndrome or Majeed syndrome. However, the association between NBO and JIA with systemic onset (soJIA) has not been described yet. Herein, we describe the cases of two patients with soJIA with inflammatory bone lesions wherein canakinumab (anti-interleukin-1β antibodies) caused remission.

Case descriptions

Patient 1-A 6-month-old boy with typical soJIA suffered a destruction of the 7th to 9th ribs and the left pubic bone. Antibiotics, IVIG, and cyclosporine proved ineffective. Corticosteroids were effective, but due to the factor of corticosteroid dependence, which has some disadvantages, canakinumab with a dosage of 4 mg/kg was initiated every 4 weeks, which completely controlled the disease and allowed to taper corticosteroids.Patient 2-A 2-year-old girl developed chronic non-bacterial osteomyelitis of the 5th rib 2 months after taking corticosteroids prescribed for typical soJIA. She underwent surgical debridement removal, and several courses of antibiotics proved ineffective. She developed macrophage activation syndrome, following which anakinra was prescribed, which resulted in only temporary improvement. Therefore, this drug was switched to canakinumab, which caused corticosteroid-free remission.

Conclusion

This is the first description of a rare association of soJIA with inflammatory bone lesions with the proven efficacy of IL-1 blockade. The association of two autoinflammatory conditions should indicate IL-1-driven mechanisms and a possible genetic basis. Follow-up genetic and functional studies are required to better understand the pathogenesis of such overlapping diseases.

Imatinib has minimal effects on inflammatory and osteopenic phenotypes in a murine cherubism model

OBJECTIVE

Cherubism is a genetic disorder characterised by bilateral jawbone deformation. The associated jawbone lesions regress after puberty, whereas severe cases require surgical treatment. Although several drugs have been tested, fundamental treatment strategies for cherubism have not been established. The effectiveness of imatinib has recently been reported; however, its pharmaceutical mechanism remains unclear. In this study, we tested the effects of imatinib using a cherubism mouse model.

METHODS

We used Sh3bp2 P416R cherubism mutant mice, which exhibit systemic organ inflammation and osteopenia. The effects of imatinib were determined using primary bone marrow-derived macrophages. Imatinib was administered intraperitoneally to the mice, and serum tumour necrosis factor-α (TNFα), organ inflammation and bone properties were examined.

RESULTS

The cherubism mutant macrophages produced higher levels of TNFα in response to lipopolysaccharide compared to wild-type macrophages, and imatinib did not significantly suppress TNFα production. Although imatinib suppressed osteoclast formation in vitro, administering it in vivo did not suppress organ inflammation and osteopenia.

CONCLUSION

The in vivo administration of imatinib had a minimal therapeutic impact in cherubism mutant mice. To establish better pharmaceutical interventions, it is necessary to integrate new findings from murine models with clinical data from patients with a definitive diagnosis of cherubism.

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.

SAPHO Syndrome Complicated by Lesions of the Central Nervous System Successfully Treated with Brodalumab

Synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome is a rare disease with an unknown entity that affects the skin and the peripheral and/or axial joints. Here, we report on a patient with SAPHO syndrome complicated by lesions of the central nervous system who was successfully treated with brodalumab, an IL-17 receptor blocker. He had been suffering from arthralgia in the wrists and knees as well as axial symptoms such as back pain and assimilation of cervical vertebrae. He had been treated with corticosteroid, salazosulfapyridine, methotrexate, and bisphosphonate; however, his peripheral and axial articular manifestation were intractable. Recently, biologics predominantly targeting TNF-α is employed for difficult-to-treat SAPHO cases; however, he had been complicated with the lesions of the central nervous system resembling multiple sclerosis (MS), an inflammatory demyelinating disorder in the central nervous system, for which application of TNF-α inhibitor is contraindicated. Alternatively, brodalumab was administered , which promptly ameliorated the articular manifestations without aggravating the lesions of the central nervous system. We propose that this type of IL-17 blockade could be an alternative therapy for DMARDs-resistant SAPHO syndrome.

Benign bony tumors of the paranasal sinuses, orbit, and skull base

Benign bony tumors of the skull base and paranasal sinuses are uncommon entities, with an overall higher incidence in males. Benign bony tumors may lead to local expansion with resultant mass effect of potentially critical structures. Some benign bony tumors may undergo malignant transformation. This article reviews the presentation and management of benign bone tumors of the skull base and paranasal sinuses with special consideration to involvement of the adjacent orbit, intracranial and critical neurovascular structures. This review covers tumor incidence, location, gross and histologic appearance as well as radiographic findings, treatment, and recurrence rates. Tumors discussed in this article include osteochondromas, osteomas, osteoid osteomas, aneurysmal bone cysts, fibrous dysplasia, giant cell tumors, cemento-ossifying fibroma, ameloblastic fibro-odontoma, ecchordosis physaliphora, chondromyxoid fibroma, primary chronic osteomyelitis, primary chronic osteomyelitis, osteochondromyxoma, and dense bone islands.

Clinical characteristics and outcomes of chronic nonbacterial osteomyelitis in children: a multicenter case series

OBJECTIVE

The aim of this study was to evaluate demographic, clinical, laboratory, imaging, histopathology characteristics, and treatment responses of children with Chronic nonbacterial osteomyelitis (CNO).

METHODS

Retrospective multi-center case series study of pediatric patients diagnosed with CNO treated at five tertiary centers in south China.

RESULTS

Totally there were 18 patients diagnosed as CNO between 2014 and 2020. The median age of onset was 9.2 years (range 3.7-13.1) and 55.6% were female. Median delay in diagnosis was 10.9 months (range 1.0-72.0). The most frequent presenting symptoms were bone pain (100%) and fever (44.4%). Most patients had more than one lesion (median of 5, range 1-7). Most frequently affected bones were tibiofibula (88.9%) and femur (77.8%). The MRI characteristics mainly presented as bone edema and hyperintensity in bone marrow. Bone biopsy was conducted in 11 patients (61.1%) with inflammatory cells infiltration manifested as chronic osteomyelitis, and none showed bacterial infection or tumor. In treatment, non-steroid anti-inflamatory drugs (NSAIDs) is used as the first-line drug followed by steriods, methotexate (MTX), salazosulfadimidine (SASP), Bisphosphonates and TNF-α inhibitor. Two refractory cases received combination therapy with Bisphosphonates and TNF-α inhibitor, and achieved good therapeutic effect.

CONCLUSIONS

The present study described a multicenter series of CNO from south China and highlighted the clinical features, laboratory tests, imaging characteristics and treatment outcomes. Increasing awareness of this disease is important to decrease time to diagnosis, improve access to treatment, and reduce complications.

Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO): A Case Report

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) is an uncommon adulthood disorder that presents as focal swellings and pain accompanied by abnormal changes in bone and surrounding soft tissues. X-rays of the involved region are usually insignificant; however, CT and MRI show excellent visualization of the affected structures. Typical radiological images show cortical thickening leading to decreased marrow cavity, bony erosion, and ligament ossifications. Other associated findings are synovitis and joint effusions. It is usually diagnosed on the basis of clinical as well as radiological findings. The treatment initially relies on non-steroidal anti-inflammatory drugs (NSAIDs). Patients showing poor response are started on corticosteroids and disease-modifying antirheumatic drugs (DMARDs). We report two patients who presented with joint swellings. Their workup unmasked the underlying SAPHO, which was managed well with NSAIDs.

Chronic Recurrent Multifocal Osteomyelitis and Its Management

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory disorder of bones first reported by Giedion et al. in 1972. It is a disease of childhood, comparable to SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) in adults. CRMO presents with pain and swelling overlying the involved bones. Inflammatory markers are usually raised and X-rays usually show sclerotic lesions. MRI demonstrates the extent of the lesions accurately and associated soft tissue changes. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids are the mainstays of the management. We report three patients who presented with bone pains. Extensive workup and radiological modalities along with clinical findings supported the diagnosis of CRMO. This article highlights important clinical presentations, radiological findings, and various management options.

Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis (SAPHO) Syndrome: Clinical and Therapeutic Aspects

Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome is a rare entity. It is frequently under-detected. We report the case of SAPHO syndrome in a 38-year-old woman, seen in consultation for pain and swelling of the anterior chest wall affecting the sternoclavicular and sternocostal joints predominantly on the right, and low back pain with an inflammatory appearance with peripheral damage, especially in the legs. We also found in our patient episodes of palmoplantar pustulosis. The diagnosis of SAPHO syndrome was retained in accordance with Kahn's diagnostic criteria, and the osteitis was confirmed by morphological examinations (CT scan, MRI, and bone scintigraphy). The patient was treated with non-steroidal anti-inflammatory drugs and methotrexate with good clinical improvement.

Role of Diagnostic Imaging in Chronic Recurrent Multifocal Osteomyelitis (CRMO) in Children: An Observational Study

The aim of this single-center observational study was to analyze the applicability of various imaging studies to the diagnosis and further evaluation of patients with chronic recurrent multifocal osteomyelitis (CRMO). The analysis included the data of 10 patients with CRMO treated between 2016 and 2021. The mean ages of the patients at the first manifestation of CRMO and ultimate diagnosis were 10 years and 7 months and 11 years and 10 months, respectively. Conventional radiography demonstrated focal loss of bone density in only 30% of the patients. Computed tomography showed disseminated foci with non-homogeneous osteolytic/osteosclerotic structure, with a massive loss of cortical layer and strong periosteal reaction. On magnetic resonance imaging (MRI), most patients presented with multifocal hypodense areas on T1-weighted images, with the enhancement of signal on T-weighted and STIR sequences. The duration of follow-up varied between 3 months and 3 years. In 40% of the patients, both clinical symptoms and the abnormalities seen on MRI resolved completely, whereas another 50% showed partial regression of clinical and radiological manifestations. MRI findings, co-existing with characteristic clinical manifestations, play a pivotal role in establishing the ultimate diagnosis of CRMO. MRI can also be used to monitor the outcomes of treatment in CRMO patients.

A Multidisciplinary Journey towards Bone Tissue Engineering

Millions of patients suffer yearly from bone fractures and disorders such as osteoporosis or cancer, which constitute the most common causes of severe long-term pain and physical disabilities. The intrinsic capacity of bone to repair the damaged bone allows normal healing of most small bone injuries. However, larger bone defects or more complex diseases require additional stimulation to fully heal. In this context, the traditional routes to address bone disorders present several associated drawbacks concerning their efficacy and cost-effectiveness. Thus, alternative therapies become necessary to overcome these limitations. In recent decades, bone tissue engineering has emerged as a promising interdisciplinary strategy to mimic environments specifically designed to facilitate bone tissue regeneration. Approaches developed to date aim at three essential factors: osteoconductive scaffolds, osteoinduction through growth factors, and cells with osteogenic capability. This review addresses the biological basis of bone and its remodeling process, providing an overview of the bone tissue engineering strategies developed to date and describing the mechanisms that underlie cell-biomaterial interactions.

Assessment of disease activity using a whole-body MRI derived radiological activity index in chronic nonbacterial osteomyelitis

BACKGROUND

Based on the recently developed ChRonic nonbacterial Osteomyelitis MRI Scoring tool (CROMRIS), we developed a radiological activity index (RAI-CROMRIS) to obtain a quantification of the overall bone involvement in individual patients.

METHODS

Whole Body Magnetic Resonance Imaging (WB-MRI) images were scored according to parameters included in the RAI-CROMRIS: bone marrow hyperintensity, signal extension, soft tissue/periosteal hyperintensity, bony expansion, vertebral collapse. These parameters were evaluated for each bone unit yielding a score from 0 to 7 and summed up as RAI-CROMRIS including all bone units. We assessed clinical disease activity using a physician global assessment (PGA) and radiological findings in 76 treatment-naïve patients; 46 of 76 were evaluated at 6 and 12 months after initial WB-MRI. Quantitative variables were compared using the Mann-Whitney U test for unmatched groups and the Wilcoxon signed-rank test for paired groups. Correlation was evaluated using Spearman's rank coefficient (r_s).

RESULTS

There was a significant correlation between RAI-CROMRIS and PGA (r_s = 0.32; p = 0.0055), between RAI-CROMRIS and presence of elevated erythrocyte sedimentation rate (p = 0.013) and C-reactive protein (p = 0.0001) at baseline. The RAI-CROMRIS decreased from a median of 17 at baseline to 12 at 6 months (p = 0.004) and remained stable (median 11) at 12 months. A correlation between the RAI-CROMRIS and the PGA was observed at baseline (r_s = 0.41; p = 0.004) and during follow up at 6 months (r_s = 0.33; p = 0.025) and 12 months (r_s = 0.38; p = 0.010). The baseline RAI-CROMRIS (median 20) was significantly higher in patients who subsequently received bisphosphonates than in patients who received other treatments (median 12) and decreased significantly after bisphosphonates (p = 0.008).

CONCLUSIONS

The RAI-CROMRIS was correlated with clinical and laboratory measures of disease activity showing significant short-term changes following treatment with bisphosphonates. This tool could be used in clinical practice and clinical trials after validation.

Cytokine profile in patients with chronic non-bacterial osteomyelitis, juvenile idiopathic arthritis, and insulin-dependent diabetes mellitus

OBJECTIVES

Our study aimed to evaluate the cytokine levels in pediatric chronic non-bacterial osteomyelitis (CNO) patients and compare these with other immune-mediated diseases and healthy controls.

METHODS

In this prospective study, we included 42 children with CNO, 28 patients with non-systemic juvenile idiopathic arthritis (JIA), 17 children with insulin-dependent diabetes mellitus (IDDM), and 30 healthy age-matched controls. In each of the CNO patients and comparison groups, the levels of 14-3-3-η protein, S100A8/A9 protein, interleukin-4 (IL-4), interleukin-17 (IL-17), interleukin-18 (IL-18), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) were measured by ELISA assay.

RESULTS

All studied cytokines in the CNO patients were significantly higher than controls, and IDDM, 14-3-3-η protein, IL-18, IL-4, IL-17, IL-1β, and TNF-α were less than in JIA patients. In the discriminant analysis, ESR, 14-3-3 protein, S100A8/A9, IL-18, IL-4, and TNF-α can discriminate CNO from JIA, and 14-3-3 protein, S100A8/A9, IL-18, IL-17, IL-4, and TNF-α can distinguish CNO from other diseases and HC.

CONCLUSION

The increased level of pro-inflammatory cytokines confirms the role of monocyte-driven inflammation in CNO patients. Cytokines may prove valuable as biomarkers and potential therapeutic targets for CNO.

Primary chronic osteomyelitis of the jaw: Rapid improvement after hormonal suppression in a girl with precocious puberty

Primary chronic osteomyelitis (PCO) of the jaw is a non-infectious, inflammatory state of the jawbone of unknown etiology. In recurrent periods, these patients often exhibit swelling of the cheek, impaired ability to open their mouth as well as pain. Available treatments today include anti-inflammatory or antiresorptive drugs, hyperbaric oxygen, surgical decortication or resection followed by reconstruction where none of them have been described to lead to restored anatomy and complete relief of symptoms. We here report the unexpected complete regression of all clinical symptoms of PCO within three months after initiating pubertal suppression therapy with a gonadotropin-releasing hormone analogue in a 9-year-old girl with PCO of the jaw and early onset of pubertal development. Radiology of the jawbone confirmed complete PCO remission when performed 18 months after starting the hormone suppression therapy. To our knowledge, total regression of PCO in such a short period of time has not been described earlier suggesting an effect of the anti-hormonal therapy per se. In this case report, we discuss possible underlying mechanisms and hypothesize that anti-hormonal treatment could be a potential effective treatment in patients with PCO of the jaw.

Periostitis Ossificans: Report of Two Cases Resolved with Endodontic Treatment

Periostitis ossificans is a chronic disease characterized by an ossifying periostitis, occurring in children and young adults, commonly as a reaction to a mild infection or irritation. It is also characterized by the presence of lamellae of newly formed periosteal bone outside the cortex, giving the characteristic radiographic appearance of “onion skin.” Aim. The aim of this paper was to present the clinical and radiographic findings, as well as the postoperative follow-up of two cases diagnosed with periostitis ossificans of dental origin, and to discuss the differential diagnosis and treatment modalities. Case Reports. In the first case, a 16-year-old adolescent was referred for a persistent mandibular swelling. Intraoral examination showed two sinus tracts in relation to the carious necrotic left mandibular first molar. The periapical radiograph showed a periapical lesion in relation to the two root canals of the left mandibular first molar. Occlusal radiographs revealed the “onion skin” bone formation aspect. In the second case, a 10-year-old girl presented to our department with a slightly painful mandibular swelling. The periapical radiograph showed a periapical lesion in relation to both the mesial and distal roots of the carious necrotic right mandibular first molar. Cone beam computed tomography (CBCT) showed a subperiosteal bone formation with an “onion skin” aspect. Diagnosis of periostitis ossificans in the two cases was confirmed and the lesion was resolved by simply an endodontic treatment. Conclusion. Specific attention should be given to clinical and radiographic exploration in case of children with mandibular swelling. As osteosarcoma can be misdiagnosed, additional examinations, such as computed tomography, can be useful in differential diagnosis and in searching malignancy signs.

A potential new target for autoinflammatory bone disease

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease mediated by the inflammatory cytokine, IL-1β. Although IL-1β is known as the key driver of bone lesions in CRMO, the signaling events leading to pathogenic levels of the cytokine are not fully understood. Using a genetic mouse model of CRMO, Dasari et al. find a role for the nonreceptor spleen tyrosine kinase (SYK) in upstream signaling leading to IL-1β up-regulation. Their findings suggest that SYK may constitute a new therapeutic target for CRMO.

A case of bone destruction caused by chronic non-bacterial osteomyelitis (CNO) successfully repaired with a tumour necrosis factor-α (TNF-α) inhibitor, adalimumab

Chronic Non-bacterial Osteomyelitis (CNO) is an autoinflammatory bone disorder that causes non-bacterial and non-neoplastic osteomyelitis. CNO appeared to the long bone, clavicle, pelvis, and spine on children commonly. This time, we report a case with osteomyelitis of the mandible for the adult-onset. A 25-year-old woman presented pustulosis palmaris/pustular psoriasis after the extraction of the lower right tooth 1 year before hospitalisation. She felt pain and swelling of the right jaw and an antibiotic, NSAIDs, and glucocorticoids were ineffective. The cortical osteotomy of right mandibular bone was carried out 2 months before hospitalisation, but the symptom was not improved and she was admitted to our hospital. For pustular psoriasis with CNO, we treated her with adalimumab and the pain and swelling in her right jaw disappeared immediately. One and two years after the treatment, osteolytic and sclerotic bone lesion and osteomyelitis were improved in both Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). An anti-TNF-α antibody may be an effective therapy for CNO resistant to conventional treatment.

[Extranodal B-cell lymphoma in the distal femur with pre-existing CRMO]

CRMO is a rare form of nonbacterial osteomyelitis, which is mainly found in children. The diagnosis is complex because bone tumors or lymphoma must also be excluded. The case report describes the development of a solitary femoral lymphoma on the basis of a known CRMO disease as well as the differential diagnostic pitfalls.

A case report of a novel compound heterozygous mutation in a Brazilian patient with deficiency of Interleukin-1 receptor antagonist (DIRA)

BACKGROUND

Deficiency of the natural antagonist of interleukin-1 was first described in 2009 and so far 20 patients has been reported. In Brazil just two cases have been reported both carrying the same homozygous 15 bp deletion. Blocking interleukin-1 has changed rate survival for DIRA patients. The use of anakinra and rilonacept has been reported safe and efficient, whereas the selective blockade of interleukin-1 beta, using the monoclonal antibody canakinumab has been reported in a single case only.

CASE PRESENTATION

Here we report a case of a 7 years old Brazilian boy that presented with recurrent episodes of systemic inflammation with severe disabling osteomyelitis with mild pustular skin rash. A Next Generation Sequencing gene panel allowed to detect two pathogenic mutations in the IL1RN gene, described in compound heterozygosity. Corticosteroids was effective in controlling inflammation and anti-IL1 beta blocker triggered disease flare. Complete clinical control could be achieved using IL-1 receptor antagonist.

CONCLUSIONS

DIRA is a severe, life threatening autoinflammatory condition with low numbers of patients described all over the world. The mutation p.Asp72_Ile76del in IL1RN is presented in all Brazilian DIRA patients already described and p.Q45* (rs1019766125) is a new mutation affecting the IL1RN gene. Following the pathogenesis of DIRA, blocking both subunits of interleukin one as well as antagonizing the receptor using anakinra or rilonacept seems to be effective. There is just one report using canakinumab for the treatment of DIRA and this is the first report of disease flare using this drug.

Mesenchymal stem cells modifications for enhanced bone targeting and bone regeneration

In pathological bone conditions (e.g., osteoporotic fractures or critical size bone defects), increasing the pool of osteoblast progenitor cells is a promising therapeutic approach to facilitate bone healing. Since mesenchymal stem cells (MSCs) give rise to the osteogenic lineage, a number of clinical trials investigated the potential of MSCs transplantation for bone regeneration. However, the engraftment of transplanted cells is often hindered by insufficient oxygen and nutrients supply and the tendency of MSCs to home to different sites of the body. In this review, we discuss various approaches of MSCs transplantation for bone regeneration including scaffold and hydrogel constructs, genetic modifications and surface engineering of the cell membrane aimed to improve homing and increase cell viability, proliferation and differentiation.

How We Manage Bone Marrow Edema-An Interdisciplinary Approach

Bone marrow edema (BME) is a descriptive term for a common finding in magnetic resonance imaging (MRI). Although pain is the major symptom, BME differs in terms of its causal mechanisms, underlying disease, as well as treatment and prognosis. This complexity together with the lack of evidence-based guidelines, frequently makes the identification of underlying conditions and its management a major challenge. Unnecessary multiple consultations and delays in diagnosis as well as therapy indicate a need for interdisciplinary clinical recommendations. Therefore, an interdisciplinary task force was set up within our large osteology center consisting of specialists from internal medicine, endocrinology/diabetology, hematology/oncology, orthopedics, pediatrics, physical medicine, radiology, rheumatology, and trauma surgery to develop a consenus paper. After review of literature, review of practical experiences (expert opinion), and determination of consensus findings, an overview and an algorithm were developed with concise summaries of relevant aspects of the respective underlying disease including diagnostic measures, clinical features, differential diagnosis and treatment of BME. Together, our single-center consensus review on the management of BME may help improve the quality of care for these patients.

The nonreceptor tyrosine kinase SYK drives caspase-8/NLRP3 inflammasome-mediated autoinflammatory osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) in humans can be modeled in Pstpip2^cmo mice, which carry a missense mutation in the proline-serine-threonine phosphatase-interacting protein 2 (Pstpip2) gene. As cmo disease in mice, the experimental model analogous to human CRMO, is mediated specifically by IL-1β and not by IL-1α, delineating the molecular pathways contributing to pathogenic IL-1β production is crucial to developing targeted therapies. In particular, our earlier findings support redundant roles of NLR family pyrin domain-containing 3 (NLRP3) and caspase-1 with caspase-8 in instigating cmo However, the signaling components upstream of caspase-8 and pro-IL-1β cleavage in Pstpip2^cmo mice are not well-understood. Therefore, here we investigated the signaling pathways in these mice and discovered a central role of a nonreceptor tyrosine kinase, spleen tyrosine kinase (SYK), in mediating osteomyelitis. Using several mutant mouse strains, immunoblotting, and microcomputed tomography, we demonstrate that absent in melanoma 2 (AIM2), receptor-interacting serine/ threonine protein kinase 3 (RIPK3), and caspase recruitment domain-containing protein 9 (CARD9) are each dispensable for osteomyelitis induction in Pstpip2^cmo mice, whereas genetic deletion of Syk completely abrogates the disease phenotype. We further show that SYK centrally mediates signaling upstream of caspase-1 and caspase-8 activation and principally up-regulates NF-κB and IL-1β signaling in Pstpip2^cmo mice, thereby inducing cmo These results provide a rationale for directly targeting SYK and its downstream signaling components in CRMO.

Dermatologic and Dermatopathologic Features of Monogenic Autoinflammatory Diseases

Autoinflammatory diseases include disorders with a monogenic cause and also complex conditions associated to polygenic or multifactorial factors. An increased number of both monogenic and polygenic autoinflammatory conditions have been identified during the last years. Although skin manifestations are often predominant in monogenic autoinflammatory diseases, clinical and histopathological information regarding their dermatological involvement is still scarce. Monogenic autoinflammatory diseases with cutaneous expression can be classified based on the predominant lesion: (1) maculopapular rashes or inflammatory plaques; (2) urticarial rashes; (3) pustular, pyogenic or neutrophilic dermatosis-like rashes; (4) panniculitis or subcutaneous nodules; (5) vasculitis or vasculopathy; (6) hyperkeratotic lesions; (7) hyperpigmented lesions; (8) bullous lesions; and (9) aphthous lesions. By using this classification, this review intends to provide clinical and histopathological knowledge about cutaneous involvement in monogenic autoinflammatory diseases.

New-Onset Chronic Recurrent Multifocal Osteomyelitis in a Child With Chronic Uveitis

Chronic recurrent multifocal osteomyelitis (CRMO) has rarely been associated with uveitis. The authors report a case of new CRMO in a 15-year-old boy with HLA-B27 positive chronic anterior uveitis controlled with methotrexate. This case highlights a potential association between chronic uveitis and CRMO. [J Pediatr Ophthalmol Strabismus. 2019;56:e38-e40.].

Chronic non-bacterial osteomyelitis in the jaw

Chronic recurrent multifocal osteomyelitis (CRMO) is one of the most severe form of chronic non-bacterial osteomyelitis (CNO), which could result in bone and related tissue damage. This autoinflammatory bone disorder (ABD) is very difficult for its clinical diagnosis because of no diagnostic criteria or biomarkers. CRMO in the jaw must be suspected in the differential diagnosis of chronic and recurrent bone pain in the jaw, and a bone biopsy should be considered in chronic and relapsing bone pain with swelling that is unresponsive to treatment. The early diagnosis of CRMO in the jaw will prevent unnecessary and prolonged antibiotic usage or unnecessary surgical intervention. The updated researches for the identification of genetic and molecular alterations in CNO/CRMO should be studied more for its correct pathophysiological causes and proper treatment guidelines. Although our trial consisted of reporting items from Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), there are very few articles of randomized controlled trials. This article was summarized based on the author's diverse clinical experiences. This paper reviews the clinical presentation of CNO/CRMO with its own pathogenesis, epidemiology, recent research studies, and general medications. Treatment and monitoring of the jaw are essential for the clear diagnosis and management of CNO/CRMO patients in the field of dentistry and maxillofacial surgery.

Autoinflammatory diseases: State of the art

Autoinflammatory diseases are characterized by innate immunity abnormalities. In autoinflammatory diseases (AID), inflammatory blood biomarkers are elevated during crisis without infection and usually without autoantibodies. The first 4 described AID were familial Mediterranean fever, cryopyrin-associated periodic fever syndrome (CAPS) or NLRP3-associated autoinflammatory disease (NRLP3-AID), mevalonate kinase deficiency (MKD) and TNFRSF1A-receptor associated periodic fever syndrome (TRAPS). Since their description 20 years ago, and with the progresses of genetic analysis, many new diseases have been discovered; some with recurrent fever, others with predominant cutaneous symptoms or even immune deficiency. After describing the 4 historical recurrent fevers, some polygenic inflammatory diseases will also be shortly described such as Still disease and periodic fever with adenitis, pharyngitis and aphtous (PFAPA) syndrome. To better explore AID, some key anamnesis features are crucial such as the family tree, the age at onset, crisis length and organs involved in the clinical symptoms. An acute phase response is mandatory in crisis.

Molecular and cellular characterizations of human cherubism: disease aggressiveness depends on osteoclast differentiation

Background

Cherubism is a rare autosomal dominant disorder of the jaws caused by mutation of the SH3BP2 gene. The bone is replaced by a fibrous granuloma containing multinucleated giant cells. Cells of the cherubism granuloma have never been systematically analyzed. Hence, the aim of this study was to characterize the cells in human cherubism granulomas, to determine the osteoclastic characteristics of the multinucleated giant cells and to investigate the potential role of TNF-α in human cherubism.

Results

Seven granulomas were analyzed in pathology, molecular biology and immunohistochemistry. Granulomas were composed mainly of macrophages or osteoclasts within a fibroblastic tissue, with few lymphoid cells. Myeloid differentiation and nuclear NFATc1 localization were both associated with disease aggressiveness. OPG and RANKL immunohistochemical expression was unexpected in our specimens. Five granuloma cells were cultured in standard and osteoclastogenic media. In culture, cherubism cells were able to differentiate into active osteoclasts, in both osteoclastogenic and standard media. IL-6 was the major cytokine present in the culture supernatants.

Conclusion

Multinucleated giant cells from cherubism granulomas are CD68 positive cells, which differentiate into macrophages in non-aggressive cherubism and into osteoclasts in aggressive cherubism, stimulated by the NFATc1 pathway. This latter differentiation appears to involve a disturbed RANK-L/RANK/OPG pathway and be less TNF-α dependent than the cherubism mouse model.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0907-2) contains supplementary material, which is available to authorized users.

Comparison of different treatment approaches of pediatric chronic non-bacterial osteomyelitis

Chronic non-bacterial osteomyelitis (CNO) is a chronic inflammatory bone disease which usually manifests in children and adolescents. There are a few data about pathogenesis and treatment. The aim of the study to compare the efficacy of different treatment approaches in pediatric CNO cohort patient. Fifty two children (25 boys and 27 girls) with CNO with average age at the onset of the disease 8.4 years (5.4; 11.0), number of foci - 3.0 (2.0; 6.0, incl. multifocal cases in 80.8%). Non-steroid anti-inflammatory drugs (NSAID) was the first-line treatment for non-vertebral cases, as well as pamidronate (PAM) for vertebral involvement. Second-line treatment includes sulfasalazine (SSZ), methotrexate (MTX), PAM and tumor necrosis factor-α inhibitors (TNFα-inh). We evaluated the dynamics of pain, patient's and physician's (MDVAS) assessment with visual-analog scale (VAS) and ability to each medication to achieve remission of CNO activity. According to the NSAID, MTX, SSZ, PAM and TNFα-inh groups the following data were registered: patient's VAS: - 14.2% (p = 0.05), - 50.0% (p = 0.04), - 23.1 (p = 0.89), - 83.3% (p = 0.0001), - 73.6% (p = 0.0007); painVAS: - 21.9% (p = 0.01), - 18.6% (p = 0.13), + 36.4 (p = 0.89), - 79.7% (p = 0.00016), - 74.1%, (p = 0.0015); MDVAS: - 13.8% (p = 0.13); - 56.4% (p = 0.09), + 30.8% (p = 0.89), - 74.7%, (p = 0.0001), - 82.1 (p = 0.0015) respectively. The ability of each treatment strategy to achieve the CNO remission was 52.6%, 44.4%, 57,1%, 88.8% and 73.3%, respectively (log-rank test, p = 0.001). The efficacy of treatment approaches for CNO depended on the severity of the disease. NSAID, methotrexate, and sulfasalazine were effective in forms without spine involvement, but pamidronate and TNF-a inhibitors were useful in vertebral forms of CNO. Pamidronate and TNF-a inhibitors more extensively suppressed CNO activity. The randomized controlled trials for assessment of the efficacy and safety of these medications is mandatory to confirm these results.

Case report: successful treatment of refractory SAPHO syndrome with the JAK inhibitor tofacitinib

INTRODUCTION

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is an autoinflammatory disorder without standardized treatment. Janus kinase (JAK) inhibitors can block a range of cytokines and might possess significant anti-inflammatory activity. Here, we report the first case of efficacious treatment of refractory SAPHO syndrome with the JAK inhibitor tofacitinib.

CASE PRESENTATION

A 44-year-old woman presented with arthralgia in the right wrist and complained of having difficulty in doing housework. Symptoms were unresponsiveness to nonsteroidal anti-inflammatory drugs, disease-modifying antirheumatic drugs, and tumor necrosis factor inhibitors. A diagnosis of SAPHO syndrome was made based on previous dermatological and osteoarticular manifestations and bone scintigraphy findings. Oral treatment with tofacitinib at 5 mg twice daily in combination with the basic methotrexate treatment was initiated. After 4 weeks of using tofacitinib, the patient reported marked improvement of symptoms and also reported being competent in completing housework.

CONCLUSIONS

The efficacy of JAK inhibitors in treating refractory SAPHO syndrome should be noted.

[Clinical overview of auto-inflammatory diseases]

Monogenic auto-inflammatory diseases are characterized by genetic abnormalities coding for proteins involved in innate immunity. They were initially described in mirror with auto-immune diseases because of the absence of circulating autoantibodies. Their main feature is the presence of peripheral blood inflammation in crisis without infection. The best-known auto-inflammatory diseases are mediated by interleukines that consisted in the 4 following diseases familial Mediterranean fever, cryopyrinopathies, TNFRSF1A-related intermittent fever, and mevalonate kinase deficiency. Since 10 years, many other diseases have been discovered, especially thanks to the progress in genetics. In this review, we propose the actual panorama of the main known auto-inflammatory diseases. Some of them are recurrent fevers with crisis and remission; some others evaluate more chronically; some are associated with immunodeficiency. From a physiopathological point of view, we can separate diseases mediated by interleukine-1 and diseases mediated by interferon. Then some polygenic inflammatory diseases will be shortly described: Still disease, Schnitzler syndrome, aseptic abscesses syndrome. The diagnosis of auto-inflammatory disease is largely based on anamnesis, the presence of peripheral inflammation during attacks and genetic analysis, which are more and more performant.

Chronic Recurrent Multifocal Osteomyelitis (CRMO): Presentation, Pathogenesis, and Treatment

PURPOSE OF REVIEW

Chronic non-bacterial osteomyelitis (CNO) with its most severe form chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disorder. We summarize the clinical presentation, diagnostic approaches, most recent advances in understanding the pathophysiology, and available treatment options and outcomes in CNO/CRMO.

RECENT FINDINGS

Though the exact molecular pathophysiology of CNO/CRMO remains somewhat elusive, it appears likely that variable defects in the TLR4/MAPK/inflammasome signaling cascade result in an imbalance between pro- and anti-inflammatory cytokine expressions in monocytes from CNO/CRMO patients. In this context, we present previously unpublished data on cytokine and chemokine expression in monocytes and tissues. CNO/CRMO is an autoinflammatory bone disorder resulting from imbalanced cytokine expression from innate immune cells. Though the exact molecular pathophysiology remains unclear, variable molecular defects appear to result in inflammasome activation and pro-inflammatory cytokine expression in monocytes from CNO/CRMO patients. Recent advances suggest signaling pathways and single molecules as biomarkers for CNO/CRMO as well as future treatment targets.

A boy with recurrent swelling of the jaw

We present a 10-year old boy with recurrent swelling of the right mandibular region. Based on the diagnosis of chronic recurrent parotitis, he received only supportive treatment. Because of frequent relapses, the diagnosis was reconsidered. Magnetic resonance imaging, scintigraphy and biopsy were compatible with chronic osteomyelitis. This lead to a diagnosis of mandibular primary chronic osteomyelitis, an uncommon non-suppurative inflammatory disease of unknown origin. After decortication of the mandible, the patient recovered well. Because there were no further complaints, the follow-up was ended 18 months after the operation.

Adult-onset Chronic Recurrent Multifocal Osteomyelitis with High Intensity of Muscles Detected by Magnetic Resonance Imaging, Successfully Controlled with Tocilizumab

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disorder that generally occurs in children and predominantly affects the long bones with marginal sclerosis. We herein report two cases of adult-onset CRMO involving the tibial diaphysis bilaterally, accompanied by polyarthritis. Magnetic resonance imaging (MRI) showed both tibial osteomyelitis and high intensity of the extensive lower leg muscles. Anti-interleukin-6 therapy with tocilizumab (TCZ) effectively controlled symptoms and inflammatory markers in both patients. High intensity of the lower leg muscles detected by MRI also improved. These cases demonstrate that CRMO should be included in the differential diagnosis of adult patients with bone pain, inflammation, and high intensity of the muscles detected by MRI. TCZ may therefore be an effective therapy for muscle inflammation of CRMO.

MECHANISMS IN ENDOCRINOLOGY: Genetics of human bone formation

Throughout life, bone is continuously remodelled to be able to fulfil its multiple functions. The importance of strictly regulating the bone remodelling process, which is defined by the sequential actions of osteoclasts and osteoblasts, is shown by a variety of disorders with abnormalities in bone mass and strength. The best known and most common example of such a disorder is osteoporosis, which is marked by a decreased bone mass and strength that consequently results in an increased fracture risk. As osteoporosis is a serious health problem, a large number of studies focus on elucidating the aetiology of the disease as well as on the identification of novel therapeutic targets for the treatment of osteoporotic patients. These studies have demonstrated that a large amount of variation in bone mass and strength is often influenced by genetic variation in genes encoding important regulators of bone homeostasis. Throughout the years, studies into the genetic causes of osteoporosis as well as several rare monogenic disorders with abnormal high or low bone mass and strength have largely increased the knowledge on regulatory pathways important for bone resorption and formation. This review gives an overview of genes and pathways that are important for the regulation of bone formation and that are identified through their involvement in monogenic and complex disorders with abnormal bone mass. Furthermore, novel bone-forming strategies for the treatment of osteoporosis that resulted from these discoveries, such as antibodies against sclerostin, are discussed as well.

Bone metabolism and inflammatory characteristics in 14 cases of chronic nonbacterial osteomyelitis

BACKGROUND

Chronic nonbacterial osteomyelitis (CNO) is a multifocal autoinflammatory disease that often impairs daily life in children. This study aimed to investigate the bone metabolic and inflammatory characteristics of patients with CNO, and to assess the differences between responders and nonresponders to conservative treatment.

METHODS

We investigated the clinical symptoms; laboratory data including inflammatory and bone metabolic biomarkers; and imaging findings from plain radiography, magnetic resonance imaging (MRI), fluorodeoxyglucose-positron emission tomography (FDG-PET), and dual-energy x-ray absorption (DEXA) in 14 patients with CNO. All patients underwent first-line treatment comprising systemic nonsteroidal anti-inflammatory drugs with or without bisphosphonate. According to the response to the first-line treatment, the patients were divided into the clinical remission/partial response group and the no response group. The differences in bone metabolic and inflammatory characteristics between the two groups were assessed.

RESULTS

All patients had low bone mineral density assessed with DEXA. The bone metabolic biomarkers (bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase 5b) were increased in boys of all ages and in young girls. Multiple inflammatory regions were detected in all patients by using FDG-PET including asymptomatic regions. The no response group had higher immunoglobulin G (IgG) and a greater number of bone inflammatory lesions detected on MRI than the clinical remission/partial response group.

CONCLUSION

Our data indicate the involvement of abnormal bone turnover, necessity of whole-body scanning, and association of higher serum IgG levels and greater numbers of inflammatory lesions with prolonged disease activity in patients with CNO.

Vasculitis in the autoinflammatory diseases

PURPOSE OF REVIEW

This article addresses the prevalence and relationship between autoinflammatory diseases and vasculitis.

RECENT FINDINGS

Autoimmune diseases (AIDs) are a group of syndromes characterized by episodes of unprovoked inflammation due to dysregulation of the innate immune system. Despite the common occurrence of rashes and other skin lesions in these diseases, vasculitis is reported in only a few. On the other hand, neutrophilic dermatoses are more prevalent. Large vessel vasculitis is reported in patients with Behcet's and Blau's syndromes. Small and medium size vasculitides are reported in familial Mediterranean fever mainly as Henoch-Schonlein purpura and polyarteritis nodosa, respectively. It is rarely described in hyper IgD with periodic fever syndrome, cryopyrin associated periodic syndromes, TNF receptor-associated periodic syndrome, deficiency of interleukin-1 receptor antagonist and pyoderma gangrenosum and acne syndrome. In most AID where bones and skin are mainly involved (CRMO, Majeed syndrome, Cherubism and DITRA) - vasculitis has not been described at all. In AID small vessel vasculitis affects mainly the skin with no involvement of internal organs.

SUMMARY

In AID, neutrophilic dermatoses are more common and prominent than vasculitis. This may reflect a minor role for interleukin-1 in the pathogenesis of vasculitis. The rarity of vasculitis in AID suggests that in most reported cases its occurrence has been probably coincidental rather than being an integral feature of the disease.

Chronic recurrent multifocal osteomyelitis exhibiting predominance of periosteal reaction

Chronic recurrent multifocal osteomyelitis is an idiopathic nonpyogenic autoinflammatory bone disorder involving multiple sites, with clinical progression persisting for more than 6 months and which may have episodes of remission and exacerbation in the long term. It represents up to 2-5% of the cases of osteomyelitis, with an approximate incidence of up to 4/1,000,000 individuals, and average age of disease onset estimated between 8-11 years, predominantly in females. The legs are the most affected, with a predilection for metaphyseal regions along the growth plate. We describe the case of a female patient, aged 2 years and 5 months, with involvement of the left ulna, right jaw and left tibia, showing a predominance of periosteal reaction as main finding.

Anakinra in a Cohort of Children with Chronic Nonbacterial Osteomyelitis

OBJECTIVE

To report efficacy and safety in patients with chronic nonbacterial osteomyelitis (CNO) unresponsive to nonsteroidal antiinflammatory drugs (NSAID) and bisphosphonates and/or glucocorticoids treated with anakinra.

METHODS

Nine patients (6 females) with refractory CNO were treated with anakinra for at least 6 months. We recorded, at baseline and after 6 months of treatment, clinical and laboratory features, and number and distribution of bone lesions detected by 99mTc-MDP bone scintigraphy. Disease activity was evaluated using a physician's global assessment (PGA).

RESULTS

At baseline, 9/9 patients had mild to severe PGA. After 6 months of treatment, in 5 patients the PGA score was graded from none to minimal. At baseline, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were elevated in 8 out of 9 patients. After 6 months, 5/9 patients had normalized CRP and ESR and in all except 1, CRP and ESR decreased. Before starting anakinra, a total of 77 bone lesions were detected by bone scintigraphy. After 6 months of treatment of the 77 lesions, 42 had resolved and 35 were stable. In 7/9 patients, 20 new lesions appeared during treatment; 2 of these 7 patients were symptomatic. At the last followup visit (median 1.7 yrs, range 0.8-2.8), 6/9 patients maintained a PGA graded as none to minimal.

CONCLUSION

Anakinra is a possible therapeutic alternative in patients with refractory CNO. The practical significance of clinically silent bone lesions detected by bone scintigraphy remains to be established.

An Update on the Pathogenesis and Treatment of Chronic Recurrent Multifocal Osteomyelitis in Children

Chronic recurrent multifocal osteomyelitis (CRMO), also known as chronic non-bacterial osteomyelitis (CNO), is a rare inflammatory disorder that primarily affects children. It is characterized by pain, local bone expansion, and radiological findings suggestive of osteomyelitis, usually at multiple sites. CRMO predominantly affects the metaphyses of long bones, but involvement of the clavicle or mandible are suggestive of the diagnosis. CRMO is a diagnosis of exclusion, and its pathogenesis remains unknown. Differential diagnosis includes infection, malignancies, benign bone tumors, metabolic disorders, and other autoinflammatory disorders. Biopsy of the bone lesion is not often required but could be necessary in unclear cases, especially for differentiation from bone neoplasia. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first-line treatment. Alternative therapies have been used, including corticosteroids, methotrexate, bisphosphonates, and tumor necrosis factor (TNF)-α inhibitors. No guidelines have been established regarding diagnosis and treatment options. This manuscript gives an overview of the most recent findings on the pathogenesis of CRMO and clinical approaches for patients with the condition.