Chronic recurrent multifocal osteomyelitis is a rare auto-inflammatory disease in children, with only a few reports of its association with other inflammatory diseases, such as systemic juvenile idiopathic arthritis. A 15-year-old boy was admitted due to fever, skin rash, arthritis, and high inflammatory factors and was finally diagnosed with systemic juvenile idiopathic arthritis. After 6 months of recovery from the disease, the patient was referred due to local pain and swelling in the arms and left thigh. In radiography, bone lesions were seen in the shoulders, left humerus, and left femoral diaphysis. A whole-body bone scan showed increased absorption in these areas, which suggested a tumor or osteomyelitis. A biopsy of the bone lesion of the left humerus confirmed sterile osteomyelitis. Although the co-incidence of chronic recurrent multifocal osteomyelitis with systemic juvenile idiopathic arthritis is rare, it should be considered in differential diagnosis.

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare autoinflammatory disease, clinically characterized by chronic and recurrent episodes of osteoarticular inflammation, that generally presents in children and adolescents. From a dermatological point-of-view, CMRO can be associated with skin rashes mainly including psoriasis, palmoplantar pustulosis and acne. Pyoderma gangrenosum (PG) is a rare immune-mediated inflammatory skin disease classified within the spectrum of neutrophilic dermatoses that, in some cases, has been reported as cutaneous manifestation in CMRO patients. This paper presents a 16-year female patient diagnosed with CMRO, who presented PG lesions located on the lower leg, that arose after the administration of the tumour necrosis factor (TNF)-α inhibitor adalimumab. Cases of PG have been reported in patients being treated with certain medications, including TNF-α antagonists, leading to classified them in a setting aptly termed \"drug-induced PG.\" In this paper, we discuss the co-occurrence of PG and CRMO, in the light of recent evidence on the pathogenesis of both diseases and giving ample space to a literature review on drug induced PG. In our case, it is plausible that PG could be considered a cutaneous manifestation of CRMO, although the mechanisms underlying this intriguingly relationship remain to be fully unraveled.

A 38-year-old female was referred with a history of fever, polyarthralgia, and bone pain. She was diagnosed with chronic recurrent multifocal osteomyelitis based on imaging and biopsy findings. Non-steroidal anti-inflammatory drugs and bisphosphonate caused no improvement. Then, she developed recurrent diarrhoea and abdominal pain. Genetic testing revealed MEFV mutation. Based on the symptoms and genetic mutation results that emerged during the course of these events, she was diagnosed with familial Mediterranean fever. All symptoms, including bone pain, improved with daily colchicine administration. This case was considered familial Mediterranean fever complicated with a clinical diagnosis of chronic recurrent multifocal osteomyelitis, which is included in the spectrum of pyrine autoinflammatory diseases. Considering this case, patients with chronic recurrent multifocal osteomyelitis with MEFV gene variants may respond to colchicine.

Multifocal bone pain in a pediatric patient prompts a broad differential diagnosis, which should include chronic recurrent multifocal osteomyelitis (CRMO), particularly when the patient has a personal or family history of autoimmune diseases or chronic inflammatory disorders. CRMO is a difficult diagnosis, as several similar disorders must be ruled out first, and it requires extensive verification based on clinical, radiological, and pathological criteria. It often mimics other medical diagnoses, including Langerhans cell histiocytosis and infectious osteomyelitis. Maintaining a high index of suspicion for CRMO is important to minimize unnecessary medical testing, optimize pain control, and preserve physical function. We present the case of a nine-year-old female who presented with multifocal bone pain and was diagnosed with CRMO.

UNASSIGNED: Osteomyelitis is a group of bone infectious (bacterial osteomyeilitis-BO) and noninfectious inflammatory diseases (nonbacterial osteomyelitis-NBO) with similar clinical, radiology, and laboratory features. Many patients with NBO are misdiagnosed as BO and receive unnecessary antibiotics and surgery. Our study aimed to compare clinical and laboratory features of NBO and BO in children, to define key discriminative criteria, and to create an NBO diagnostic score (NBODS).
UNASSIGNED: The retrospective multicenter cohort study included clinical, laboratory, and instrumental information about histologically confirmed NBO (n = 91) and BO (n = 31). The variables allowed us to differentiate both conditions used to construct and validate the NBO DS.
UNASSIGNED: The main differences between NBO and BO are as follows: onset age-7.3 (2.5; 10.6) vs. 10.5 (6.5; 12.7) years (p = 0.03), frequency of fever (34.1% vs. 90.6%, p = 0.0000001), symptomatic arthritis (67% vs. 28.1%, p = 0.0001), monofocal involvement (28.6% vs. 100%, p = 0.0000001), spine (32% vs. 6%, p = 0.004), femur (41% vs. 13%, p = 0.004), foot bones (40% vs. 13%, p = 0.005), clavicula (11% vs. 0%, p = 0.05), and sternum (11% vs. 0%, p = 0.039) involvement. The following four criteria are included in the NBO DS: CRP ≤ 55 mg/l (56 points), multifocal involvement (27 points), femur involvement (17 points), and neutrophil bands ≤ 220 cell/μl (15 points). The sum > 17 points allowed to differentiate NBO from BO with a sensitivity of 89.0% and a specificity of 96.9%.
UNASSIGNED: The diagnostic criteria may help discriminate NBO and BO and avoid excessive antibacterial treatment and surgery.

Chronic recurrent multifocal osteomyelitis (CRMO) is a non-infectious inflammatory disorder resulting from the multifocal bone and bone marrow lesions with periodic relapses and remissions and with an uncertain prognosis. Treatment options in CRMO are based on expert opinion and relatively small groups of patients. A nine-year-old female patient with no significant past medical history presented with compression fractures and multifocal bone lesions in the thoracic and lumbar spine, as shown in imaging (CT, MRI). Densitometry revealed a diffuse decrease in bone density. Based on the patient\'s clinical image and above examinations, the other possible aetiologies-infectious (including tuberculosis), neoplasms, Langerhans cell histiocytosis-were ruled out, which led to eventual final diagnosis-CRMO. The patient was successfully treated with pamidronate infusion initiated in cycles over three consecutive days every 3 months. In addition to clinical improvement, there was a significant remission of inflammation and bone structure healing assessed by MRI after four treatment cycles. Intravenous bisphosphonates usage seems to be a good therapeutic option in CRMO paediatric patients with spinal localization of the lesions complicated by compressive fractures. However, more data, based on larger patient populations, are needed to provide a detailed paediatric CRMO treatment algorithm.

Chronic recurrent multifocal osteomyelitis (CRMO) is an unusual form of non-microbial chronic osteomyelitis. It is an exclusion diagnosis that can only be considered after ruling out infectious osteomyelitis and bone tumors. We report the case of a 13-year-old girl who was admitted for a painful swelling of the left thigh. Biological examinations did not find an inflammatory syndrome. X-rays and Magnetic Resonance Imaging were very suggestive of malignant bone tumor. But the biopsy disclosed a nonspecific osteomyelitis. Considering the strong suspicion of a malignant origin, a second biopsy was performed and confirmed the diagnosis of osteomyelitis. During the hospital stay, the patient developed a second location in the left humerus. Thus, the diagnosis of CRMO was retained. The patient was treated by NSAIDs with good clinical and radiological outcomes. This case report reminds the diagnostic challenge of this pathology that can mimic malignant tumor.

We present a 9-year-old girl with persistent pain and swelling of the left wrist. X-ray, magnetic resonance imaging (MRI) and bone biopsy led to the diagnosis of chronic recurrent multifocal osteomyelitis (CRMO), affecting phalangeal and metacarpal bases and distal carpal bones on the ulnar side of the wrist. She was treated with non-steroidal anti-inflammatory drugs and complete remission with no long-term sequelae was achieved. CRMO is a rare auto-inflammatory condition with infrequent involvement of the hand. The current literature is discussed. The aim of this report is to raise awareness of the condition to reduce the time to diagnosis and unnecessary antibiotic treatment and to prevent permanent disability due to the progression of the disease. Level of Evidence: Level V (Therapeutic).

Chronic recurrent multifocal osteomyelitis (CRMO) is a rarely reported autoimmune inflammatory condition affecting children and young adults. The typical complaint is recurrent severe bone pain at multiple sites; often imaging suggests features of osteomyelitis or malignancy. However, the biopsy is always negative for any growth in culture and histopathology detects only inflammatory cells. This is a diagnosis of exclusion with various diagnostic criteria. We had a 20-year-old male presenting with recurring pain and swelling in the right hand and left foot for more than seven months. Imaging revealed bone marrow edema with the expansion of bone and sclerosis involving the third metacarpal of the right hand and first metatarsal of the left foot. Acute phase reactants were mildly raised with biopsy showing inflammatory cells. However, the cultures grown from the lesion were sterile. After comparing it with the various diagnostic criteria, a diagnosis of CRMO was made.

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.