Distinguishing Osteomyelitis From Ewing Sarcoma on Radiography and MRI

Xanthogranulomatous osteomyelitis: multimodality imaging of a rare case involving tibial diaphysis with review of literature

The case report discusses xanthogranulomatous osteomyelitis, a rare inflammatory bone condition that can resemble malignancy on imaging studies. The report details a case of a 42-year-old woman with left leg pain, swelling, and redness lasting 4 months. Imaging revealed a lytic lesion in the left tibia with endosteal erosion, and MRI showed extraosseous soft tissue extension. An open biopsy confirmed xanthogranulomatous osteomyelitis. Following surgical curettage and bone grafting, the patient recovered well at subsequent follow-ups until 1 year after surgery. The article emphasizes the importance of distinguishing xanthogranulomatous osteomyelitis from other malignancies and discusses its epidemiology, clinical presentation, diagnostic techniques, and relevant imaging features, highlighting the potential for misdiagnosis based on overlapping characteristics with conditions like lymphoma and Ewing sarcoma.

Musculoskeletal Infection: The Great Mimickers on Imaging

A series of conditions can mimic musculoskeletal infections on imaging, complicating their diagnosis and affecting the treatment. Depending on the anatomical location, different conditions can manifest with clinical and imaging findings that mimic infections. Herein we present a wide spectrum of the musculoskeletal disorders of the axial skeleton, long bones, peripheral joints, and soft tissue that may manifest as infectious processes, and we focus on the potential mimics of osteomyelitis, septic arthritis, and infectious spondylodiscitis that are common in clinical practice. We present the typical imaging characteristics of each musculoskeletal infection, followed by mimicking conditions.

How to distinguish a benign from a malignant tumour in children and when should a biopsy be done and by whom

Bone tumours are frequent in children but most of them are benign. Moreover, the incidence and type of tumours differ from those of adults. As an orthopaedic surgeon, we will likely encounter a bone lesion in a child and we must be able to distinguish if it is a benign lesion or has malignant characteristics and it is necessary to refer it to a centre specialized in tumours. We will discuss the key points we would have to ask in the medical history, look at the physical examination and the radiological characteristics that will allow us to distinguish between a benign and a malignant bone lesion in a child. When there are doubts about the malignancy of a bone lesion or if the diagnosis is not clear, a biopsy should be performed following certain rules in a specialized centre.

Pelvic Ewing Sarcoma: The Great Mimicker

Ewing sarcoma is the most common malignant bone tumor of the pelvis in children and young adults. Even with aggressive treatment, its survival rate is amongst the poorest. Classical presentation may not be the rule. It may simulate clinically, imagiologically and histopathologically other nonmalignant entities. Therefore, its suspicion should not be overlooked. We report two cases of pelvic Ewing sarcoma: the first mimicking eosinophilic granuloma, and the second mimicking osteomyelitis. In the latter, we also report an atypical finding of its natural history: an initial response to antibiotic and anti-inflammatory treatment. In both cases, we highlight the possibility of an inconclusive percutaneous bone biopsy and the importance of immunochemistry and cytogenetics for the definitive diagnosis.

Bad to the bone. Not all bone tumors are cancer: Case of long bone osteomyelitis

Long bone osteomyelitis could mimic bony tumor in clinical presentation and imaging studies. We present a case of a 47-year man who presented with leg pain, weight loss and night sweats that initially was thought to be related to osteosarcoma, later suffered a pathologic fracture from Staphylococcus aureus osteomyelitis. This case highlights the importance of source control of infection and careful clinical evaluation including radiographic and pathologic findings that can help physicians to differentiate between competing diagnoses.

Application of Machine Learning for Differentiating Bone Malignancy on Imaging: A Systematic Review

An accurate diagnosis of bone tumours on imaging is crucial for appropriate and successful treatment. The advent of Artificial intelligence (AI) and machine learning methods to characterize and assess bone tumours on various imaging modalities may assist in the diagnostic workflow. The purpose of this review article is to summarise the most recent evidence for AI techniques using imaging for differentiating benign from malignant lesions, the characterization of various malignant bone lesions, and their potential clinical application. A systematic search through electronic databases (PubMed, MEDLINE, Web of Science, and clinicaltrials.gov) was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 34 articles were retrieved from the databases and the key findings were compiled and summarised. A total of 34 articles reported the use of AI techniques to distinguish between benign vs. malignant bone lesions, of which 12 (35.3%) focused on radiographs, 12 (35.3%) on MRI, 5 (14.7%) on CT and 5 (14.7%) on PET/CT. The overall reported accuracy, sensitivity, and specificity of AI in distinguishing between benign vs. malignant bone lesions ranges from 0.44–0.99, 0.63–1.00, and 0.73–0.96, respectively, with AUCs of 0.73–0.96. In conclusion, the use of AI to discriminate bone lesions on imaging has achieved a relatively good performance in various imaging modalities, with high sensitivity, specificity, and accuracy for distinguishing between benign vs. malignant lesions in several cohort studies. However, further research is necessary to test the clinical performance of these algorithms before they can be facilitated and integrated into routine clinical practice.

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

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

Tumors of the Spine: When Can Biopsy Be Avoided?

Regarding osseous tumors of the spine, characteristic morphology is encountered in hemangioma of the vertebral body, osteoid osteoma (OO), osteochondroma, Paget's disease, and bone islands. In these cases, radiologic imaging can make a specific diagnosis and thereby avoid biopsy, especially when the radiologist has chosen the correct imaging modality to establish the diagnosis, such as thin-slice computed tomography in suspected OO. A benign lesion is suggested by a high amount of fat within the lesion, the lack of uptake of the contrast agent, and a homogeneous aspect without solid parts in a cystic tumor. Suspicion of malignancy should be raised in spinal lesions with a heterogeneous disordered matrix, distinct signal decrease in T1-weighted magnetic resonance imaging, blurred border, perilesional edema, cortex erosion, and a large soft tissue component. Biopsy is mandatory in presumed malignancy, such as any Lodwick grade II or III osteolytic lesion in the vertebral column. The radiologist plays a crucial role in determining the clinical pathway by choosing the imaging approach wisely, by narrowing the differential diagnosis list, and, when characteristic morphology is encountered, by avoiding unnecessary biopsies.

ACR Appropriateness Criteria® Osteomyelitis or Septic Arthritis-Child (Excluding Axial Skeleton)

Imaging plays an integral role in the evaluation of suspected musculoskeletal infections in children, not only in the accurate identification of infection such as osteomyelitis or septic arthritis, but also in guiding management. Various diagnostic modalities serve different purposes in the assessment of suspected pediatric musculoskeletal infections. The purpose of this document is to provide imaging guidance in the most frequently encountered clinical scenarios in which osteomyelitis and/or septic arthritis are suspected, outside of the axial skeleton. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion.

Multiparametric MRI evaluation of bone sarcomas in children

Osteosarcoma and Ewing sarcoma are the most common bone sarcomas in children. Their clinical presentation is very variable depending on the age of the patient and tumor location. MRI is the modality of choice to assess these bone sarcomas and has an important function at diagnosis and also for monitoring recurrence or tumor response. Anatomic sequences include T1- and T2-weighted images and provide morphological assessment that is crucial to localize the tumor and describe anatomical boundaries. Multiparametric MRI provides functional information that helps in the assessment of tumor response to therapy by using different imaging sequences and biomarkers. This review manuscript illustrates the role of MRI in osteosarcoma and Ewing sarcoma in the pediatric population, with emphasis on a functional perspective, highlighting the use of diffusion-weighted imaging and dynamic contrast-enhanced MRI at diagnosis, and during and after treatment.

Educational Case: Osteoid Osteoma

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

Osteomyelitis infection disguised as Reiter's syndrome in a child: A case report

Reiter's syndrome (reactive arthritis) should always prompt a thorough clinical investigation of a potentially more serious disease condition in every pediatric patient and adults. It should always be regarded as a warning sign and not a disease. This is a case of a 16-year-old African boy with osteomyelitis presenting with symptoms of reactive arthritis (Reiter's syndrome).

EWS-FLI1-targeting peptide identifies Ewing sarcoma tumor boundaries and lymph node metastasis via near-infrared imaging

Ewing sarcoma (ES) is one of the most aggressive types of pediatric tumors. The lack of tools for the identification of ES has largely hindered clinical diagnosis and the improvement of treatment. To address this challenge, we synthesized a near‐infrared (NIR) fluorescent probe (CS2‐N‐E9R) that targets the ES‐specific fusion protein EWS–FLI1 (E/F). This probe exhibited specific and high binding affinity to E/F. Further studies in animal models showed that CS2‐N‐E9R can be used to identify the boundaries of ES and lymph node metastases under a complex biological environment. These results demonstrate that CS2‐N‐E9R is a promising probe for early diagnosis and surgical guidance of ES through molecularly targeted NIR imaging.

Acute osteoarticular infections in children are frequently forgotten multidiscipline emergencies: beyond the technical skills

Acute osteoarticular infections (AOI) should be treated as top emergencies. The first few days following the inception of infection are ultra-critical to long-term prognosis.A comprehensive road map for management of childhood AOI is still lacking despite recent advances in microbiology and imaging (magnetic resonance imaging). The many faces of childhood AOI warrant a multidiscipline approach to management.Laboratory and imaging findings of are still debatable and should not overshadow or delay a management plan based on the experienced physician's clinical judgment.Ample evidence-based practice supports the use of a few days of intravenous antibiotic administration followed by oral therapy until correlative clinical and basic laboratory (acute phase reactants) results improve.The growing body of evidence on 'high-risk' children/neonates of AOI warrants continual clinical extra-vigilance in identifying these patient subsets.Open drainage and debridement remain the mainstay of treatment of septic hips, whereas for other joints the use of alternative surgical techniques should be individualized or on case-by-case basis.Because the consequences of misdiagnosis of AOI are usually grave and permanent, proactive treatment/overtreatment is justified in the event of unconfirmed but suspicious diagnosis. Cite this article: EFORT Open Rev 2021;6:584-592. DOI: 10.1302/2058-5241.6.200155.

[Bone and soft tissue tumours in children : Proposal for a rational diagnostic approach]

CLINICAL/METHODOLOGICAL ISSUE

Bone and soft tissue tumours are often incidental findings in children. Because they are usually benign tumours, nonspecialised radiologists generally have little experience in the diagnosis and differentiation from malignant tumours. Various imaging techniques are used in the diagnosis of skeletal tumours.

STANDARD RADIOLOGICAL METHODS

Imaging techniques used to evaluate bone and soft tissue tumours include sonography, computed tomography (CT) and magnetic resonance imaging (MRI).

METHODOLOGICAL INNOVATIONS

An algorithm to determine malignancy of bone and soft tissue tumours in children is proposed.

PERFORMANCE

By using the presented algorithms, further diagnostic procedures such as biopsies can be avoided in the majority of children with bone and soft tissue tumours. Aggressive bone lesions and unclear soft tissue tumours are guided to biopsy to confirm diagnosis.

ACHIEVEMENTS

The algorithms presented are based on the proposals of European professional societies and have been adapted by the authors for use in children and adolescents.

PRACTICAL RECOMMENDATIONS

In the clarification of soft tissue tumours, sonography is the first diagnostic tool; depending on the sonographic findings, MRI is the technique for further clarification. Biopsy confirmation of the diagnosis in unclear cases or in cases of probable malignancy should be carried out in a paediatric oncology centre.

Ewing Sarcoma-Diagnosis, Treatment, Clinical Challenges and Future Perspectives

Ewing sarcoma, a highly aggressive bone and soft-tissue cancer, is considered a prime example of the paradigms of a translocation-positive sarcoma: a genetically rather simple disease with a specific and neomorphic-potential therapeutic target, whose oncogenic role was irrefutably defined decades ago. This is a disease that by definition has micrometastatic disease at diagnosis and a dismal prognosis for patients with macrometastatic or recurrent disease. International collaborations have defined the current standard of care in prospective studies, delivering multiple cycles of systemic therapy combined with local treatment; both are associated with significant morbidity that may result in strong psychological and physical burden for survivors. Nevertheless, the combination of non-directed chemotherapeutics and ever-evolving local modalities nowadays achieve a realistic chance of cure for the majority of patients with Ewing sarcoma. In this review, we focus on the current standard of diagnosis and treatment while attempting to answer some of the most pressing questions in clinical practice. In addition, this review provides scientific answers to clinical phenomena and occasionally defines the resulting translational studies needed to overcome the hurdle of treatment-associated morbidities and, most importantly, non-survival.

A Holistic Approach to Bone Tumors in Dogs and Cats: Radiographic and Histologic Correlation

The skeletal system is a common site for neoplasia in dogs and cats, and primary bone tumors may develop from any of the mesenchymal tissues present in bone. Imaging and histopathology are routinely used in the diagnosis of bone tumors, and the 2 techniques are highly complementary. While imaging may be highly suggestive of a specific diagnosis and treatment may be instituted based on this, definitive diagnosis requires histopathology of either incisional or excisional biopsies or an amputation specimen. However, there are a number of diagnostic dilemmas when the pathologist interprets bone biopsy samples, such as distinguishing reactive bone and tumor bone, fracture callus and tumor bone, different benign fibro-osseous lesions, and different types of bone sarcoma. This review outlines the characteristic radiographic and histologic changes associated with these diagnostic problems to aid in resolving them. When a holistic approach is taken to evaluation of the signalment, history, and clinical, radiologic, and microscopic features, a diagnosis may be possible. The pathologist is greatly assisted in the interpretation of bone samples by having access to imaging and should routinely request either the images or the imaging reports if they are not received from submitting veterinarians.

Pearls and Pitfalls for Soft-Tissue and Bone Biopsies: A Cross-Institutional Review

Management of soft-tissue and bone neoplasms depends on a definitive histologic diagnosis. Percutaneous image-guided biopsy of bone and soft-tissue tumors is a cost-effective and accurate method to obtain a histopathologic diagnosis. Biopsy requests must be approached thoughtfully to avoid numerous potential pitfalls. Hasty biopsy planning places the patient at increased risk for misdiagnosis, delayed therapy, repeated invasive procedures, and substantial morbidity. Biopsy planning begins with a thorough review of the relevant clinical history and pertinent imaging. The biopsy route must be planned in concert with the referring orthopedic oncologist to preserve limb-sparing options. Carefully selecting the most appropriate imaging modality to guide the biopsy increases the chances of reaching a definitive diagnosis. It is also critical to identify and target with expertise the part of the lesion that is most likely to yield an accurate diagnosis. Percutaneous biopsy is a safe procedure, and familiarity with preprocedural laboratory testing parameters, anticoagulation guidelines, and commonly used sedation medications minimizes the risk of complications while ensuring patient comfort. Nondiagnostic biopsy results are not infrequent and may still have value in guiding patient treatment. Awareness of the imaging manifestations of tumor recurrence is also important. The aim of this article is to provide a comprehensive review of pertinent preprocedural, periprocedural, and postprocedural considerations for bone and soft-tissue musculoskeletal biopsies.The online slide presentation from the RSNA Annual Meeting is available for this article.^©RSNA, 2020.

MRI nomenclature for musculoskeletal infection

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

Langerhans cell histiocytosis of the shoulder girdle, pelvis and extremities: a review of radiographic and MRI features in 85 cases

OBJECTIVES

To describe the radiographic and MRI features of histologically proven Langerhans cell histiocytosis (LCH) of the bone.

MATERIALS AND METHODS

A retrospective review of the radiographic and MRI features of 85 histologically proven cases of skeletal LCH over a 12-year period. Clinical data recorded included age, gender and location. Radiographic features evaluated included Lodwick grading, cortical/periosteal response and matrix mineralisation. MRI features assessed included lesion size and T1-weighted signal intensity (T1W SI), nature of margin, hypointense rim, enhancement pattern, bone marrow and soft tissue oedema, soft tissue mass, fluid-fluid levels, the penumbra sign and the budding and bulging signs.

RESULTS

The study included 85 patients, 54 males and 31 females with mean age of 13 years (range 1-76 years). The femur was the commonest bone involved (38.8%), followed by the scapula (9.4%), clavicle (8.2%), ilium (8.2%) and ischium (8.2%). The mean maximal lesion size was 40 mm (range 16-85 mm). The commonest radiographic appearance was of a lytic lesion with no appreciable sclerotic rim, an intact expanded cortex and either absent or laminated periosteal response. MRI demonstrated a hypointense rim (41.5%), the budding (31.7%) and bulging (36.6%) signs, eccentric extra-osseous mass (42.7%), prominent bone marrow (95.3%) and soft tissue oedema (84.1%). Rarer features included haemorrhage (2.4%), the penumbra sign (3.5%) and fluid-fluid levels (2.4%). Thirteen of 25 post-contrast studies showed peripheral/rim enhancement with central necrosis.

CONCLUSIONS

LCH classically presents as a moderately aggressive lytic bone lesion on radiography, with prominent reactive bone and soft tissue oedema being a characteristic feature on MRI.

Periosteal Reaction Possibly Induced by Pazopanib: A Case Report and Literature Review

BACKGROUND

Although complications associated with pazopanib, a multitarget tyrosine kinase inhibitor, are known, periosteal reaction as a side effect has never been reported.

OBSERVATION

We present a case involving a male pediatric patient with desmoid tumors treated for 6 months with pazopanib who presented with pain and periosteal reaction in the ilium and scapula. Three months after termination of pazopanib therapy, the periosteal reaction in the scapula resolved and that in the ilium improved.

CONCLUSION

Children receiving pazopanib presenting with focal pain should be examined for the periosteal reaction; this knowledge may facilitate correct diagnosis of symptoms as a drug-associated finding.

Image-guided core needle biopsy for Ewing sarcoma of bone: a 10-year single-institution review

OBJECTIVE

To evaluate the performance of image-guided core needle biopsy (IGCNB) for the diagnosis of Ewing sarcoma of bone.

METHODS

All patients with a confirmed diagnosis of Ewing sarcoma who underwent IGCNB between January 2007 and December 2016 were included in this retrospective study. Analysis included mean age, skeletal distribution, imaging modality used for biopsy guidance, type of anaesthesia, needle type, number of passes, type of tissue sampled, and complications.

RESULTS

The study included 139 patients (94 males and 45 females; mean age 18.7 years) who underwent 141 image-guided core needle biopsies as the primary diagnostic test. Of these, 101 were CT-guided, 38 ultrasound-guided, and 2 utilised both CT and ultrasound guidance. A total of 97.9% were diagnostic at first procedure. Of the 3 non-diagnostic cases, 2 underwent a further IGCNB and were positive, while 1 patient required an open surgical procedure. Only 1 patient (0.7%) suffered an immediate complication, and there were no recorded delayed complications.

CONCLUSION

IGCNB is a safe procedure providing a positive diagnosis of Ewing sarcoma of bone in a very high percentage of cases. It should be the first-line method for establishing a diagnosis in suspected Ewing sarcoma of bone.

KEY POINTS

• Image-guided core needle biopsy is a safe procedure providing a positive diagnosis of Ewing sarcoma of bone in a very high percentage of cases. • Image-guided core needle biopsy should be the first-line method for establishing a definitive diagnosis in Ewing sarcoma and should be performed at a specialist sarcoma referral centre. • When technically feasible, extra-osseous soft tissue alone can be sampled with confidence as there is no difference in diagnostic performance whether bone or an extra-osseous soft tissue component of the tumour is sampled.

Imaging Features of Bone Tumors: Conventional Radiographs and MR Imaging Correlation

Imaging bone tumors often causes uncertainty, especially outside dedicated sarcoma treatment centers. Conventional radiography remains the backbone of bone tumor diagnostics, but MR imaging has a role. Radiographs are crucial for assessing the tumor matrix and aggressiveness. MR imaging is the best modality for local staging. This article reviews semiological aspects of bone tumors: patient age, tumor localization, pattern of bone destruction/margins, aggressiveness, growth speed, matrix formation, periosteal reaction, cortical involvement, size, and number of lesions. All aspects are discussed in terms of their appearance on radiographs and MR imaging, with a focus on the correlation between the 2 modalities.

Imaging Analyses of Bone Tumors

Despite the evolution in imaging, especially the introduction of advanced imaging technologies, radiographs still are the key for the initial assessment of a bone tumor. Important aspects to be considered in radiographs are the location, shape and size or volume, margins, periosteal reaction, and internal mineralization of the tumor's matrix; careful evaluation of these may provide for accurate diagnosis in >80% of cases. Computed tomography and magnetic resonance imaging are often diagnostic for lesions with typical findings such as the nidus of osteoid osteoma and bone destruction such as in Ewing sarcoma and lymphoma that may be difficult to detect with radiographs; they may also be used for surgical planning. Magnetic resonance imaging accurately determines the intraosseous extent and articular and vascular involvement by the tumor. This article summarizes the diagnostic accuracy of imaging analyses in bone tumors and emphasizes the specific radiographic findings for optimal radiographic diagnosis of the patients with these tumors.

Distinguishing bone and soft tissue infections mimicking sarcomas requires multimodal multidisciplinary team assessment

INTRODUCTION

The aims of this study were to report the presenting characteristics and identify how best to distinguish bone and soft-tissue infections that mimic sarcomas.

MATERIALS AND METHODS

A total of 238 (211 osteomyelitis and 27 soft-tissue infections) patients referred to a tertiary sarcoma multidisciplinary team with suspected sarcoma who were ultimately diagnosed with a bone or soft tissue infection were included. Data from a prospectively collated database was analysed retrospectively.

RESULTS

Of all possible bone and soft-tissue sarcoma referrals, a diagnosis of infection was made in 2.1% and 0.7%, respectively. Median age was 18 years in the osteomyelitis group and 46 years in the soft-tissue infection group. In the osteomyelitis group, the most common presenting features were pain (85.8%) and swelling (32.7%). In the soft-tissue infection group, the most common clinical features were swelling (96.3%) and pain (70.4%). Those in the soft-tissue group were more likely to have raised inflammatory markers. Radiological investigations were unable to discern between tumour or infection in 59.7% of osteomyelitis and 81.5% of soft-tissue infection cases. No organism was identified in 64.9% of those who had a percutaneous biopsy culture.

CONCLUSIONS

This study has highlighted that infection is frequently clinically indistinguishable from sarcoma and remains a principle non-neoplastic differential diagnosis. When patients are investigated for suspected sarcoma, infections can be missed due to falsely negative radiological investigations and percutaneous biopsy. As no single clinical, biochemical or radiological feature or investigation can be relied upon for diagnosis, clinicians should have a low threshold for tissue biopsy and discussion in a sarcoma multidisciplinary team meeting.

Extended field of view magnetic resonance imaging for suspected osteomyelitis in very young children: is it useful?

BACKGROUND

Osteomyelitis is a challenging diagnosis for clinicians, particularly in very young children. At our institution, the magnetic resonance imaging (MRI) protocol in suspected osteomyelitis for children 5 years of age or younger includes a large field of imaging regardless of the clinical site of concern.

OBJECTIVE

To determine if extended field of view (FOV) MRI contributes important information in young children with suspected osteomyelitis.

MATERIALS AND METHODS

A retrospective study was performed including children 5 years of age or younger with suspected osteomyelitis from January 2011 to September 2015. All children underwent coronal fluid-sensitive MRI from neck to feet. Focused imaging was performed as necessary on abnormal sites depicted on survey imaging. Two radiologists reviewed the imaging findings, which were compared to the clinical outcome.

RESULTS

We studied 51 children with a mean age of 2.2 years (range: 21 days-5.5 years); 53% were boys. Osteomyelitis was depicted by MRI in 20 subjects (39.2%). Survey coronal fluid-sensitive imaging was accomplished by adding a single fluid-sensitive series in 1 child, 2 series in 31 children, 3 series in 16 children and 4 series in 3 children. Survey imaging added a median total time of 6:51 min to the examination (range: 2.29-20.54 min). Extended FOV imaging added important information in 11/51 subjects (21.6%), in 6 cases (11.8%) of infection and in 5 cases (9.8%) by suggesting alternative diagnoses.

CONCLUSION

The addition of extended FOV MRI in young children with suspected osteomyelitis added important clinical information in 21.6% of patients while only adding a median of 6:51 min to the examination. It is our experience that in children ≤5 years of age with suspected osteomyelitis, extended FOV imaging adds important information and may result in changes in management.

Role of fluoroethyl tyrosine positron emission tomography-computed tomography scan in differentiating ewing's sarcoma from osteomyelitis

Ewing's sarcoma is a kind of undifferentiated reticulocytic sarcoma, which was first reported in 1921 by James Ewing. It is difficult to differentiate Ewing's sarcoma from osteomyelitis on computed tomography (CT) and X-ray and hence cytological confirmation is needed. Fluorodeoxy glucose being a nonspecific tracer cannot differentiate between malignant and inflammatory lesions. However, it is found that Ewing's sarcoma has increased LAT1 transporter expression at the cell surface. This property has been utilized to specifically target the tumor cells and differentiate them from inflammatory lesions. ¹⁸F-fluoroethyl tyrosine (FET) is a radiotracer which shows increased uptake in tumors having LAT1 expression and no uptake in inflammatory lesions. Thus, FET positron emission tomography-computed tomography can serve as a useful tool in diagnosing recurrence or residual Ewing's sarcoma from infective pathology. Besides, it is also helpful in monitoring response to therapy.

Diagnostic value of MRI signs in differentiating Ewing sarcoma from osteomyelitis

Background

The value of magnetic resonance imaging (MRI) signs in differentiating Ewing sarcoma from osteomyelitis has not be thoroughly investigated.

Purpose

To investigate the value of various MRI signs in differentiating Ewing sarcoma from osteomyelitis.

Material and Methods

Forty-one patients who underwent MRI because of a bone lesion of unknown nature with a differential diagnosis that included both Ewing sarcoma and osteomyelitis were included. Two observers assessed several MRI signs, including the transition zone of the bone lesion, the presence of a soft-tissue mass, intramedullary and extramedullary fat globules, and the penumbra sign.

Results

Diagnostic accuracies for discriminating Ewing sarcoma from osteomyelitis were 82.4% and 79.4% for the presence of a soft-tissue mass, and 64.7% and 58.8% for a sharp transition zone of the bone lesion, for readers 1 and 2 respectively. Inter-observer agreement with regard to the presence of a soft-tissue mass and the transition zone of the bone lesion were moderate (κ = 0.470) and fair (κ = 0.307), respectively. Areas under the receiver operating characteristic curve of the diameter of the soft-tissue mass (if present) were 0.829 and 0.833, for readers 1 and 2 respectively. Mean inter-observer difference in soft-tissue mass diameter measurement ± limits of agreement was 35.0 ± 75.0 mm. Diagnostic accuracies of all other MRI signs were all < 50%.

Conclusion

Presence and size of a soft-tissue mass, and sharpness of the transition zone, are useful MRI signs to differentiate Ewing sarcoma from osteomyelitis, but inter-observer agreement is relatively low. Other MRI signs are of no value in this setting.

Distinguishing Ewing sarcoma and osteomyelitis using FTIR spectroscopy

The differential diagnosis of Ewing sarcoma and osteomyelitis can be challenging and can lead to delays in treatment with possibly devastating results. In this retrospective, small-cohort study we demonstrate, that the Fourier Transformed Infrared (FTIR) spectra of osteomyelitis bone tissue can be differentiated from Ewing sarcoma and normal bone tissue sampled outside tumour area. Significant differences in osteomyelitis samples can be seen in lipid and protein composition. Supervised learning using a quadratic discriminant analysis classifier was able to differentiate the osteomyelitis samples with high accuracy. FTIR spectroscopy, alongside routine radiological and histopathological methods, may offer an additional tool for the differential diagnosis of osteomyelitis and ES.

Pulmonary metastases in children: are we operating unnecessarily?

OBJECTIVE

to determine, in pediatric patients with malignant neoplasms, the characteristics of pulmonary nodules identified on computed tomography, as well as the possibility of differentiating benign lesions from metastases.

METHODS

we conducted a retrospective study of patients submitted to pulmonary resections of nodules diagnosed as metastases in a period of seven years. We compared computed tomography and surgery findings, as well as results of anatomopathological examinations.

RESULTS

we studied nine patients submitted to 11 surgical interventions. Among the studied variables, only nodule size greater than 12.5mm proved to be statistically significant to predict malignancy.

CONCLUSION

among the tomographic characteristics of pulmonary nodules in children with malignant neoplasms, only the size of the lesion was a predictor of malignancy.

Diagnostic value of 99mTc-ubiquicidin scintigraphy in differentiation between osteomyelitis and bone tumors

AIM

The differentiation of osteomyelitis from bone tumors is of great importance in clinical decision-making; however, the features of both osteomyelitis and bone tumors are noncontributory. Tc-ubiquicidin scintigraphy is a new promising method with the ability to specifically localize the infection site by bacterial cell membrane binding. This study aimed to evaluate the ability of this radiopeptide for the differentiation of these two entities.

PATIENTS AND METHODS

Thirty consecutive patients (mean age=20.9 years) suspected of having either osteomyelitis or bone tumor were included in this prospective study. A Tc-UBI scan was performed in both dynamic and static phases and the images were assessed qualitatively and semiquantitatively. The final diagnosis was established for 29 patients on the basis of surgical findings and microbiological and pathology assessments as well as any other clinical, laboratory, or imaging findings during patient follow-up.

RESULTS

The final diagnosis was infectious and noninfectious processes in 19 and 10 patients, respectively. Visual assessment could not distinguish between osteomyelitis and bone tumors. However, the time-activity pattern of the images proved to be promising. The sensitivity, specificity, negative and positive predictive value, and accuracy of the time-activity curve for osteomyelitis were 73.6 (54-93), 100, 66.6 (43-91), 100, and 82%, respectively. The mean±SD tumor/nontumor (T/NT) ratios for 30 min images were 2.22±0.45 and 2.02±0.51 for infectious and noninfectious processes, respectively (P=0.29). Using a cutoff value of 0.97 for the T/NT ratio, the sensitivity and specificity were calculated to be 78.9 and 50%, respectively.

CONCLUSION

Although Tc-UBI scintigraphy in the dynamic imaging format was very useful with high accuracy in differentiating between infectious and tumoral lesions, it was not useful to distinguish these two entities on the basis of visual assessment or T/NT ratio measurement on static images. The study also showed the high accuracy of this noninvasive modality in acute osteomyelitis with low diagnostic value in chronic infectious processes.

Non-odontogenic tumors of the facial bones in children and adolescents: role of multiparametric imaging

Tumors of the pediatric facial skeleton represent a major challenge in clinical practice because they can lead to functional impairment, facial deformation, and long-term disfigurement. Their treatment often requires a multidisciplinary approach, and radiologists play a pivotal role in the diagnosis and management of these lesions. Although rare, pediatric tumors arising in the facial bones comprise a wide spectrum of benign and malignant lesions of osteogenic, fibrogenic, hematopoietic, neurogenic, or epithelial origin. The more common lesions include Langerhans cell histiocytosis and osteoma, while rare lesions include inflammatory myofibroblastic and desmoid tumors; juvenile ossifying fibroma; primary intraosseous lymphoma; Ewing sarcoma; and metastases to the facial bones from neuroblastoma, Ewing sarcoma, or retinoblastoma. This article provides a comprehensive approach for the evaluation of children with non-odontogenic tumors of the facial skeleton. Typical findings are discussed with emphasis on the added value of multimodality multiparametric imaging with computed tomography (CT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI), positron emission tomography CT (PET CT), and PET MRI. Key imaging findings and characteristic histologic features of benign and malignant lesions are reviewed and the respective role of each modality for pretherapeutic assessment and post-treatment follow-up. Pitfalls of image interpretation are addressed and how to avoid them.

Unexpectedly high incidences of chronic non-bacterial as compared to bacterial osteomyelitis in children

Historically, osteomyelitis was considered an infectious disorder. More recently, inflammatory mechanisms were recognized causing a significant proportion of pediatric osteomyelitis. This study was to compare characteristics of children with chronic non-bacterial (CNO) and bacterial osteomyelitis (BOM). A chart review of osteomyelitis patients from the departments of pediatrics, pediatric surgery, orthopedic surgery, and oral and maxillofacial surgery was conducted in a tertiary referral center, covering the years 2004-2014. Institutional incidences of CNO (n = 49) and BOM (n = 56) were comparable. Differentiation between CNO and BOM based on clinical or laboratory findings was mostly impossible. However, children with BOM more frequently presented with local inflammatory signs (47 vs. 68 %, p = 0.040), fever (12 vs. 38 %, p = 0.003), and abscesses (0 vs. 39 %, p < 0.001). Peripheral arthritis (14 vs. 0 %, p < 0.001), inflammatory bowel disease (10 vs. 2 %, p = ns), and hyperostosis (29 vs. 4 %, p = 0.001) were more common in CNO. Whole-body MRI was performed in 76 % of CNO patients, unveiling multifocal lesions in 80 % (CRMO). Though considered a rare disorder, institutional incidences of CNO were comparable to BOM, and the discrimination between CNO and BOM solely based on clinical aspects was mostly impossible. This is of special interest, since a correct and timely diagnosis is of utmost importance for long-term outcomes in both disorders. Whole-body MRIs should be considered in chronic osteomyelitis to (1) detect clinically inapparent lesions in CNO and (2) indirectly exclude (usually unifocal) chronic bacterial infections. Prospective studies are warranted to establish evidence-based diagnostic and therapeutic approaches to CNO.

A Case of Acute Osteomyelitis: An Update on Diagnosis and Treatment

Osteomyelitis in children is a serious disease in children requiring early diagnosis and treatment to minimize the risk of sequelae. Therefore, it is of primary importance to recognize the signs and symptoms at the onset and to properly use the available diagnostic tools. It is important to maintain a high index of suspicion and be aware of the evolving epidemiology and of the emergence of antibiotic resistant and aggressive strains requiring careful monitoring and targeted therapy. Hereby we present an instructive case and review the literature data on diagnosis and treatment.

Abdominal mass hiding rib osteomyelitis

BACKGROUND

Rib osteomyelitis is a rare entity, occurring in approximately 1 % or less of all cases of haematogenous osteomyelitis. Given its rarity and clinical heterogeneity, the diagnosis of rib osteomyelitis can be challenging and requires a high index of suspicion. We present a case of acute osteomyelitis of the rib due to community-acquired methicillin-resistant Staphylococcus aureus (MRSA), which occurred in an otherwise healthy 3-month-old infant and mimicked an epigastric hernia at first.

CASE PRESENTATION

An otherwise healthy 3-month-old female infant was sent by her primary care paediatrician to the paediatric emergency department for possible incarcerated epigastric hernia because for 2 days, she had suffered from mild to moderate fever, irritability, poor feeding, and tender epigastric swelling. Ultrasonographic imaging excluded epigastric hernia, and transthoracic echocardiography ruled out endocarditis. However, clinical assessment combined with laboratory criteria classified the child into the high-risk group for having severe bacterial infection. Consequently, awaiting the definitive diagnosis, she was immediately treated with a broad-spectrum regimen of intravenous antibiotic therapy based on vancomycin (40 mg/kg/die in 3 doses) and meropenem (100 mg/kg/die in 3 doses). Three days after admission, the blood culture result was positive for methicillin-resistant Staphylococcus aureus, and vancomycin remained as antibiotic therapy. On day 3, a second swelling appeared at the level of the seventh left rib, 2 cm-wide, non-erythematous, mildly painful. Ultrasonography of the left chest wall on this occasion showed an image consistent with an acute osteomyelitis of the anterior osteo-chondral region of the 7th rib and associated adjacent periosteal and soft tissue collection and magnetic resonance imaging confirmed the osteomyelitis of the anterior middle-distal part of the 7th left rib, near the costochondral junction. Vancomycin was continued up to a total of 6 weeks of therapy, and at the end, the child was discharged in good condition with no relapse during the follow-up.

CONCLUSION

This is one of the few reported cases of paediatric rib osteomyelitis caused by community-acquired MRSA. Timely identification associated with prompt and targeted antibiotic therapy may allow full recovery.