Is PET-CT an accurate method for the differential diagnosis between chondroma and chondrosarcoma?

A promising role of noble metal NPs@MOFs in chondrosarcoma management

Chondrosarcoma, a challenging and malignant neoplasm originating from cartilage cells, poses significant diagnostic and therapeutic hurdles due to its resistance to conventional treatments and the complexity of its diagnosis. Noble metal nanoparticle-embedded metal-organic frameworks (NPs@MOFs) stand out as a novel approach for the diagnosis and treatment of chondrosarcoma. This review delves into the properties and applications of NPs@MOFs, focusing on their classification by noble metal type and their role in enhancing photothermal therapy (PTT), photodynamic therapy (PDT), targeted drug delivery and chondrosarcoma diagnosis. Despite promising in vitro and in vivo results, challenges such as understanding the mechanisms of action and clinical translation remain, and the therapeutic effect of PTT and PDT on deep chondrosarcoma seems unsatisfactory. Future exploration, such as combined therapy and multiple MOF therapy, could unlock the full potential of noble metal NPs@MOFs in revolutionizing chondrosarcoma management, offering insights into the prospect of these materials in chondrosarcoma management.

The role of positron emission tomography in the evaluation and management of musculoskeletal lesions-a narrative review

Background and Objective

The role of positron emission tomography (PET) in evaluating musculoskeletal lesions has evolved significantly over the past several decades. When combined with conventional imaging, PET can provide substantial value, but understanding its optimal use and potential pitfalls is crucial. This literature review highlights the current role of PET in common bone and soft tissue sarcomas (STS), PET-positive benign lesions, differentiating between benign and malignant lesions, and evaluating skeletal lesions from primary carcinomas. Furthermore, we review the future potential of PET in this evolving landscape.

Methods

In this literature review article, PubMed, Cochrane Library, and Google Scholar databases were searched for studies and reviews on the management of musculoskeletal tumors with PET-computed tomography (CT) scans with focus on bone and STS.

Key Content and Findings

This review elucidates the optimal scenarios for employing PET/CT in managing musculoskeletal tumors and highlights potential pitfalls. A key strength of this study is the correlation of patient case imaging, effectively demonstrating practical applications of PET/CT.

Conclusions

PET imaging serves as a valuable tool for diagnosis, staging, and surveillance of musculoskeletal tumors, particularly sarcomas. With a multidisciplinary approach and ongoing research, PET/CT is poised to become a leading method in the management of musculoskeletal tumors.

Multimodality imaging features of parosteal lipomas

OBJECTIVE

To examine the multimodality imaging characteristics of parosteal lipomas.

MATERIALS AND METHODS

With IRB approval, our institutional imaging database and medical record were retrospectively reviewed from 1990-2020 for cases of pathologically-proven and/or imaging diagnosed parosteal lipomas.

RESULTS

There were 22 patients (12 males, 10 females) with a mean age of 57.1 ± 12.7 years (range 31-80 years). 11/22 cases (50%) were pathologically-confirmed on biopsy or surgical resection and 11/22 (50%) had imaging features compatible with parosteal lipoma. Lesions occurred most commonly along the femur (8/22, 36%), followed by the forearm (3/22, 14%). All cases demonstrated a juxtacortical fatty mass containing an osseous excrescence that was firmly attached to the cortical surface. The osseous excrescences were characterized as pedunculated in 16/22 (73%) and sessile in 6/22 (27%). The average largest dimension of the osseus excrescences was 2.4 ± 1.6 cm (range 0.8-6.1 cm) and the lipomatous portions 7.8 ± 3.8 cm (range 2.0-19.5 cm). The excrescences contained mature bone in 12/22 (55%) cases and a mixture of mature bone and radiating bone spicules in 10/22 (45%). There were non-lipomatous elements in the fatty portion of the mass in 13/22 (59%) of cases. Most cases (19/22, 85%) had cortical thickening/periostitis near the base of the osseous stalk. Two patients had a bone scan that demonstrated uptake in the osseous excrescence, and two patients had an FDG PET/CT that demonstrated no uptake.

CONCLUSION

Parosteal lipomas are a rare benign lipomatous tumor with pathognomonic multimodality imaging features that may obviate the need for biopsy.

Is a radiological score able to predict resection-grade chondrosarcoma in primary intraosseous lesions of the long bones?

Aims

The preoperative grading of chondrosarcomas of bone that accurately predicts surgical management is difficult for surgeons, radiologists, and pathologists. There are often discrepancies in grade between the initial biopsy and the final histology. Recent advances in the use of imaging methods have shown promise in the ability to predict the final grade. The most important clinical distinction is between grade 1 chondrosarcomas, which are amenable to curettage, and resection-grade chondrosarcomas (grade 2 and 3) which require en bloc resection. The aim of this study was to evaluate the use of a Radiological Aggressiveness Score (RAS) to predict the grade of primary chondrosarcomas in long bones and thus to guide management.

Methods

A total of 113 patients with a primary chondrosarcoma of a long bone presenting between January 2001 and December 2021 were identified on retrospective review of a single oncology centre's prospectively collected database. The nine-parameter RAS included variables from radiographs and MRI scans. The best cut-off of parameters to predict the final grade of chondrosarcoma after resection was determined using a receiver operating characteristic curve (ROC), and this was correlated with the biopsy grade.

Results

A RAS of ≥ four parameters was 97.9% sensitive and 90.5% specific in predicting resection-grade chondrosarcoma based on a ROC cut-off derived using the Youden index. Cronbach's α of 0.897 was derived as the interclass correlation for scoring the lesions by four blinded reviewers who were surgeons. Concordance between resection-grade lesions predicted from the RAS and ROC cut-off with the final grade after resection was 96.46%. Concordance between the biopsy grade and the final grade was 63.8%. However, when the patients were analyzed based on surgical management, the initial biopsy was able to differentiate low-grade from resection-grade chondrosarcomas in 82.9% of biopsies.

Conclusion

These findings suggest that the RAS is an accurate method for guiding the surgical management of patients with these tumours, particularly when the initial biopsy results are discordant with the clinical presentation.

Can 18F-FDG PET/CT alone or combined with radiology be used to reliably grade cartilage bone neoplasms for surgical decision making?

OBJECTIVE

Treatment of chondrosarcomas is grade based; intralesional curettage for grade 1 and resection for grade 2 or more. Currently used methods to determine grades before surgery are not highly accurate and create a dilemma for the surgeon. We have used a PET-CT combined with imaging to answer the following study questions: (1) Does SUVmax value from an 18F-FDG PET/CT correlate with the grade of chondrosarcoma? (2) Can a cutoff SUVmax value be used to differentiate between various grades of chondroid neoplasms with sufficient sensitivity and specificity? (3) Does SUVmax guide the clinician and add value to radiology in offering histologic grade-dependent management?

METHODS

SUVmax values of patients with suspected chondrosarcoma were retrospectively correlated with the final histology grade for the operated patients. Radiologic parameters and radiology aggressiveness scores (RAS) were reevaluated and tabulated.

RESULTS

Totally 104 patients with chondroid tumors underwent 18F-FDG PET/CT assessment. In total 73 had tissue diagnosis available as a pretreatment investigation. Spearman correlation indicated that there was a significant positive association between SUVmax and the final histology grading of chondroid tumors (correlation coefficient = 0.743; P < 0.01). SUVmax cutoff of 13.3 was 88.9% sensitive and 100% specific for diagnosing dedifferentiated chondrosarcomas. An RAS cutoff value of 3 or more could diagnose IHGCS with a sensitivity of 80.7% and specificity of 93.75%. Adding an SUVmax cutoff of 3.6 improves the sensitivity to 89.5%.

CONCLUSION

SUVmax value can reliably help diagnose dedifferentiated chondrosarcoma and when added to the radiology score can improve the accuracy of grading chondrosarcoma.

A Review of Posteromedial Lesions of the Chest Wall: What Should a Chest Radiologist Know?

A heterogeneous group of tumors can affect the posteromedial chest wall. They form diverse groups of benign and malignant (primary or secondary) pathologies that can arise from different chest wall structures, i.e., fat, muscular, vascular, osseous, or neurogenic tissues. Chest radiography is very nonspecific for the characterization of chest wall lesions. The modality of choice for the initial assessment of the chest wall lesions is computed tomography (CT). More advanced cross-sectional modalities such as magnetic resonance imaging (MRI) and positron emission tomography (PET) with fluorodeoxyglucose are usually used for further characterization, staging, treatment response, and assessment of recurrence. A systematic approach based on age, clinical history, and radiologic findings is required for correct diagnosis. It is essential for radiologists to be familiar with the spectrum of lesions that might affect the posteromedial chest wall and their characteristic imaging features. Although the imaging findings of these tumors can be nonspecific, cross-sectional imaging helps to limit the differential diagnosis and determine the further diagnostic investigation (e.g., image-guided biopsy). Specific imaging findings, e.g., location, mineralization, enhancement pattern, and local invasion, occasionally allow a particular diagnosis. This article reviews the posteromedial chest wall anatomy and different pathologies. We provide a combination of location and imaging features of each pathology. We will also explore the role of imaging and its strengths and limitations for diagnosing posteromedial chest wall lesions.

Common Skeletal Neoplasms and Nonneoplastic Lesions at 18F-FDG PET/CT

Numerous primary and metastatic osseous lesions and incidental osseous findings are encountered at fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT. These lesions show varying degrees of FDG uptake. Malignancies are generally more FDG avid than are benign lesions, but many exceptions exist. Although aggressive lesions tend to be more FDG avid than nonaggressive lesions, this concept holds true particularly for lesions of the same histologic subtype. In addition, some benign osseous processes such as Paget disease have variable degrees of FDG avidity on the basis of disease metabolic activity. This creates a diagnostic dilemma for radiologists and clinicians, especially in patients with known malignancies, and can result in unnecessary diagnostic imaging or interventions for incidental osseous lesions. Evaluation of morphologic CT characteristics of osseous lesions at FDG PET/CT can be a valuable adjunct to metabolic analysis to further characterize lesions, enhance diagnostic and staging accuracy, and avoid unnecessary invasive biopsy procedures. The authors review the common primary and metastatic bone lesions at FDG PET/CT, with an emphasis on morphologic CT assessment of lesions to help narrow the differential diagnosis. Imaging manifestations of common incidental nonneoplastic bone lesions at FDG PET/CT are discussed to provide information on differentiation of these lesions from osseous neoplasms. The guidelines of the National Comprehensive Cancer Network (NCCN) for common primary osseous malignancies are also summarized. Online supplemental material is available for this article. ^©RSNA, 2021.

Atypical Cartilaginous Tumors: Trends in Management

INTRODUCTION

Chondrosarcomas are the most common primary bone malignancy in adults within the United States. Low-grade chondrosarcomas of the long bones, now referred to as atypical cartilaginous tumors (ACTs), have undergone considerable changes in recommended management over the past 20 years, although controversy remains. Diagnostic needle biopsy is recommended only in ambiguous lesions that cannot be clinically diagnosed with a multidisciplinary team. Local excision is preferred due to better functional and equivalent oncologic outcomes. We sought to determine whether these changes are reflected in reported management of ACTs.

METHODS

The National Cancer Database (NCDB) 2004 to 2016 was queried for ACTs of the long bones. Reported patient demographics and tumor clinicopathologic findings were extracted and compared between patients who underwent local excision versus wide resection.

RESULTS

We identified 1174 ACT patients in the NCDB. Of these, 586 underwent local excision and 588 underwent wide resection. No significant differences were found in patient demographics. No significant change was found in the reported percentage of diagnostic biopsies or wide resections performed over time. After multivariate regression, the single greatest predictor of performing wide resection on an ACTs was presenting tumor size.

DISCUSSION

Evaluation of the NCDB demonstrated that despite changes in the recommended management of ACTs, there has not been a significant change in surgical treatment over time. Surgeons have been performing diagnostic biopsies and wide resections at similar to historical rates. Persistency of these practices may be due to presenting tumor size, complex anatomic location, uncertainty of underlying tumor grade, or patient choice as part of clinical shared decision making. The authors anticipate that the rate of biopsies and wide resections performed will decrease over time as a result of improvements in advanced imaging and the implementation of recently updated clinical practice guidelines.

Conventional Cartilaginous Tumors: Evaluation and Treatment

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Enchondromas are benign cartilaginous lesions that rarely require surgical intervention.

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Atypical cartilaginous tumors (ACTs), also referred to as grade-1 chondrosarcomas, may be managed without any intervention or with extended intralesional curettage and bone-void filling.

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High-grade chondrosarcomas, or grade-2 and 3 chondrosarcomas, should be managed aggressively with wide resection.

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Chemotherapy and radiation do not currently play a role in the treatment of chondrosarcomas.

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Differentiating an enchondroma from an ACT and an ACT from a high-grade chondrosarcoma can be difficult and requires clinical experience, radiographic and advanced imaging, and possibly a biopsy. Ultimately, a multidisciplinary team that includes a musculoskeletal oncologist, a radiologist, and a pathologist is needed to make the most appropriate diagnosis and treatment plan for each patient.

The role of imaging in differentiating low-grade and high-grade central chondral tumours

Chondrosarcoma is a malignant cartilage matrix-producing tumour. Those arising de novo are called primary chondrosarcomas and are the second commonest primary malignant bone tumours. Numerous types of primary chondrosarcoma exist, namely conventional central (intramedullary), periosteal (juxta-cortical), clear cell, mesenchymal, and dedifferentiated. The biologic aggressiveness, prognosis and thus management of chondrosarcoma are dependent on the histological sub-type and grade. Accurate pre-operative diagnosis is therefore essential in determining management and outcome which requires a multidisciplinary approach taking into account clinical features, imaging findings and histopathology. In this review, we present the pertinent multimodality imaging features which aid in the differentiation of low-grade and high-grade conventional central chondrosarcoma.

Solitary enchondromas-diagnosis and surveillance : Danish guidelines

Enchondromas (EC) are frequent incidental findings on magnetic resonance imaging (MRI) performed for the diagnosis of joint pathology, especially observed on MRI examinations of the knee and shoulder. Enchondroma has potential for malignant transformation to chondrosarcoma (CS), and it may be difficult to distinguish EC from low-malignant CS on the basis of imaging or histopathology studies. Therefore, EC is mostly followed up to monitor any growth and/or changes indicating aggressive tumor.There is no consensual evidence on when and how to follow up patients with EC with regard to potential malignant transformation. Therefore, the Danish Multidisciplinary Cancer Groups initiated and supported the elaboration of Danish guidelines in 2020 based on a literature review. The guidelines are presented here, in addition to a summary of the background literature.

Intra-cranial Chondroma: A Case Report and Problematic Diagnosis

Introduction:

Chondroma is a benign cartilaginous tumor. It is found very rarely in the head and neck.

Case presentation:

This report describes a 25-year-old woman who presented with generalized headache from 4 months ago. The patient underwent excisional surgery. The histological examinations revealed benign cartilage forming tumor, compatible with chondroma. The radiologic and histologic correlation confirmed the diagnosis. Based on the diagnosis, the patient received no more treatment.

Conclusion:

We concluded that intracranial chondroma should be included in the differential diagnosis of a calcified mass on skull imaging. Proper diagnosis is necessary for further patient management.

The utility of 18F-FDG PET and PET/CT in the diagnosis and staging of chondrosarcoma: a meta-analysis

OBJECTIVE

Chondrosarcoma is the second most common primary bone sarcoma; however, unlike other tumors, the biopsy cannot easily make a definite diagnosis or predict the histological grade. This meta-analysis was performed to evaluate the utility of ¹⁸F-FDG PET and PET/CT to differentiate chondrosarcoma from benign cartilaginous lesions and to predict the histopathological grade of chondrosarcoma.

MATERIAL AND METHODS

A comprehensive search was performed in three electronic databases including Medline/PubMed, the Cochrane Library and Embase to retrieve diagnostic studies evaluating the role of ¹⁸F-FDG PET or PET/CT for appraising the status of chondrosarcoma. Reference lists of related articles were also scrutinized manually. Useful data were extracted to calculate the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), the summary receiver operating characteristic curve (sROC), and the area under the curve (AUC) of ¹⁸F-FDG PET or PET/CT in diagnosing chondrosarcoma, and pooled weighted mean differences (WMD) of maximum standardized uptake value (SUVmax) between different entities of cartilaginous neoplasms by using Stata 19.0.

RESULTS

A total of twelve studies provided sufficient data for the quantitative analysis. For the diagnosis of chondrosarcoma, the pooled sensitivity, specificity, and DOR of ¹⁸F-FDG PET were 0.84 (95% confidence interval [CI] 0.46 to 0.97), 0.82 (95% CI 0.55 to 0.94), and 24.244 (95% CI 1.985 to 96.148), respectively while those of ¹⁸F-FDG PET/CT were 0.94 (95% CI 0.86 to 0.97), 0.89 (95% CI 0.82 to 0.93), and 112.999 (95% CI 41.341 to 308.866), respectively. The pooled WMD of SUVmax were - 0.89 (95% CI -1.67 to -0.10) between benign cartilaginous lesions and grade 1 (G1) chondrosarcoma, -1.94 (95% CI -2.76 to -1.12) between G1 and grade 2 (G2) chondrosarcoma, and - 2.37 (95% CI -5.79 to 1.05) between G2 and grade 3 (G3) chondrosarcoma.

CONCLUSIONS

In a word, ¹⁸F-FDG PET/CT revealed excellent accuracy in the diagnosis of chondrosarcoma and might assist in clinical decision-making. Meanwhile, although SUVmax alone showed restricted ability to differentiate benign cartilaginous lesions and G1 chondrosarcoma, as well as between G2 and G3 chondrosarcoma, it can identify intermediate/high-grade chondrosarcoma from low-grade ones.

LEVEL OF EVIDENCE

Level I evidence, a summary of meta-analysis.

The role of Thallium-201 scintigraphy and Tc-99m pentavalent dimercaptosuccinic acid in diagnosis and grading of chondrosarcoma

PURPOSE

Distinguishing between enchondromas and low-grade (grade 1) chondrosarcomas can be challenging. The aim of this study was to investigate the role of Thallium-201 scintigraphy and Technetium-99 m pentavalent dimercaptosuccinic acid (Tc-99 m DMSA (V)) in the diagnosis and grading of chondrosarcomas.

METHODS

232 consecutive patients with pathologically proven cartilaginous tumours between the years 2000 and 2018 were evaluated. We included 197 patients (101 males and 96 females; median age 50 years; range 15-86 years) who underwent Thallium-201(n = 193) and/or Tc-99 m DMSA (V) scanning (n = 67). Increased uptake was defined as uptake greater than background. The reference standard was the histopathological assessment based on a grading system (grade 1-3). Data was analysed using multivariate modelling.

RESULTS

There were 46 patients with enchondromas and 151 with chondrosarcomas. Of those, 64 (enchondroma n = 21, chondrosarcoma n = 43) underwent both Thallium-201 and Tc-99 m DMSA (V). Thallium-201 uptake had 7.92 times greater odds of grade 1 chondrosarcomas than enchondromas. Thallium-201 uptake was significantly associated with the odds of a higher grade chondrosarcoma (grade 2-3). DMSA (V) positivity was associated with 4.75 times the odds of a chondrosarcoma diagnosis over enchondroma (p = 0.024). DMSA (V) uptake revealed no association with chondrosarcoma grading.

CONCLUSION

Low-grade chondrosarcomas continue to pose a diagnostic dilemma. Thallium-201 scans may identify malignancy in benign appearing tumours as well as differentiate between low-grade and high-grade chondrosarcomas in said malignancies. DMSA (V) may be useful in distinguishing between benign and malignant entities as a whole.

Laryngeal gout mimicking chondrosarcoma with concurrent longus colli tendinitis

A 42-year-old man with multiple comorbidities, including gout, presented to the emergency department with severe odynophagia for 4 days with intermittent dysphagia for 1-2 months. A CT scan of the neck showed right longus colli tendinitis and partially calcified excrescences from the right thyroid cartilage which raised suspicion of a cartilaginous tumour. He underwent an MRI scan of the neck to better evaluate the thyroid cartilage findings, which showed a heterogeneous mass suspicious for a chondroid tumour. He then underwent a positron-emission tomography-CT scan which showed a fluorodeoxyglucose-avid mass containing foci of calcification involving the right thyroid cartilage and adjacent strap muscle, with high standardised uptake value of 7.7. He subsequently underwent a CT-guided biopsy and an open biopsy of the right thyroid cartilage, and the results revealed gouty tophi. To our knowledge, this is the first reported case of laryngeal gout with longus coli tendinitis, both of which are rare conditions.

Diagnostic accuracy of functional imaging modalities for chondrosarcoma: A systematic review and meta-analysis

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Functional imaging modalities may have an important role in diagnosing chondrosarcomas.

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PET is a sensitive and specific test for differentiating chondrosarcomas and benign chondroid tumours.

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Thallium-201 scintigraphy has a high positive predictive value for chondrosarcomas.

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DMSA (V) has a 100% negative predictive value and can be used to rule out chondrosarcomas.

Introduction

The distinction between low-grade (grade 1) chondrosarcoma and its benign counterparts can be challenging. This systematic review aims to quantify the diagnostic accuracies of all functional imaging modalities used in the diagnosis of chondrosarcoma.

Methods

Medline and Embase were searched in February 2019. We included studies of either retrospective or prospective design if the results of functional scans were compared with pre-determined reference standards. Studies had to be primary diagnostic reports on patients with chondral tumours at first diagnosis. Two review authors independently performed study selection, extracted data and assessed the methodological quality. We calculated diagnostic accuracy measures for each included study.

Results

Four functional imaging modalities were identified across thirteen studies that met the inclusion criteria. 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) was a sensitive and specific test. Technetium-99 m with methylene diphosphonate (Tc-99 m MDP) had an overall low specificity of 4%. Thallium-201 scintigraphy demonstrated high positive predictive values across the studies. The negative predictive values of Technetium-99 m pentavalent dimercaptosuccinic acid (Tc-99 m DMSA (V)) were consistently 100%.

Conclusions

Low-grade chondrosarcomas continue to pose a diagnostic dilemma. FDG-PET demonstrated superior diagnostic accuracy compared to Tc-99 m MDP, Thallium-201 and Tc-99 m DMSA (V). Characteristic uptake patterns of Thallium-201 and Tc-99 m DMSA (V) may provide additional metabolic information to guide the diagnosis in this challenging group of tumours.

18F-FDG PET/CT in the evaluation of cartilaginous bone neoplasms: the added value of tumor grading

OBJECTIVES

Cartilaginous bone tumors represent a wide variety of neoplasms ranging from benign to extremely aggressive malignant lesions. Unlike other tumors, the biopsy cannot easily predict the histological grade, sometimes not allowing choosing the best therapeutic approach. The aim of the study was to evaluate the ability of ¹⁸F-FDG PET/CT to differentiate enchondroma from chondrosarcoma and to predict the histological grade as compared to biopsy.

METHODS

¹⁸F-FDG PET/CT of 95 patients with chondroid lesions were retrospectively evaluated. The best SUV_max cutoff to predict the post-surgical histological grade were correlated to those of biopsy and to several radiologic aggressiveness features, which were summarized in the parameter "Radiologic Aggressiveness Score" (AgSCORE).

RESULTS

A concordance between the preoperative biopsy and the definitive histological grade was observed overall in 78.3% of patients, the lowest accuracy (58.6%) being in the identification of intermediate/high-grade chondrosarcoma (G2/G3). The best SUV_max cutoff was 2.6 to discriminate enchondroma vs. low-grade chondrosarcoma (sensitivity 0.68, specificity 0.86), 3.7 to differentiate low-grade vs. intermediate/high-grade chondrosarcoma (sensitivity 0.83, specificity 0.84) and 7.7 to differentiate intermediate/high-grade vs. dedifferentiated chondrosarcoma (sensitivity 0.92, specificity 0.9). The AgSCORE also showed a high accuracy to differentiate between G1 and G2/G3 chondrosarcoma (cutoff = 4; sensitivity 0.76; specificity 0.89). An even higher accuracy was observed in those cases in which both SUV_max and AgSCORE cutoff were concordant.

CONCLUSIONS

Results in this large series of patients suggest a potential role of ¹⁸F-FDG PET/CT for histological grading of cartilaginous tumors, thus helping the orthopedic surgeon towards the most appropriate surgical procedure.

Can 18F-FDG PET/CT diagnose malignant change in benign chondroid tumors?

AIM

The aim of this study was to determine whether fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) can diagnose malignant change in benign chondroid tumors.

PATIENTS AND METHODS

This study included patients with clinicoradiological features of a chondroid tumor who were referred for a F-FDG PET/CT study to evaluate clinical suspicion of malignant change. Metabolic characteristics of the suspected lesion in the form of maximum standardized uptake value (SUVmax) was obtained and compared with histopathology. In patients who were treated conservatively and for whom histopathology was not available, stability of the lesion on clinical/radiological follow-up was used as reference standard. Receiver operating characteristic curve analysis was performed to obtain a SUVmax cutoff value to differentiate between benign and malignant lesions.

RESULTS

Clinical and imaging data of 66 patients was available for analysis. Malignancy was confirmed by histopathology in 40/66 (60.6%) patients with grade 2 chondrosarcomatous change seen in majority. In 26 patients, the final diagnosis was benign tumor (osteochondroma, n=19; enchondroma, n=7). Median SUVmax of malignant lesions was significantly higher compared with the benign lesions (4.0 vs. 2.1, P=0.00). A SUVmax cutoff of 3.1 could differentiate a benign lesion from those with malignant transformation with a sensitivity of 90.3% and specificity of 87% (area under the curve=0.92). Dedifferentiated sarcomas showed a significantly higher uptake than rest of the sarcoma types.

CONCLUSION

F-FDG PET/CT can detect malignant change in benign chondroid neoplasms by showing higher metabolic activity in the area of sarcomatous transformation. It can also identify focus of dedifferentiation which has prognostic and therapeutic implications.

Musculoskeletal Pitfalls on Fluorodeoxyglucose F 18 PET-Computed Tomography: Pictorial Review

A wide range of musculoskeletal processes can demonstrate increased uptake on PET-computed tomography (CT) with fluorodeoxyglucose (FDG) F 18, including reactive, benign neoplastic, inflammatory, traumatic, posttreatment, and arthritic conditions that may mimic malignancy. In addition, physiologic causes of increased FDG uptake such as asymmetric muscle use and presence of brown fat can lead to increased FDG uptake and potential false-positive results. This article presents various case examples of non-malignant musculoskeletal hypermetabolism on 18F-FDG PET-CT and describes useful tools to avoid the potential pitfall of misinterpreting these as malignancy.

Applications of PET/CT and PET/MR Imaging in Primary Bone Malignancies

Primary bone malignancies are characterized with anatomic imaging. However, in recent years, there has been an increased interest in PET/computed tomography scanning and PET/MRI with fludeoxyglucose F 18 for evaluating and staging musculoskeletal neoplasms. These hybrid imaging modalities have shown promise largely owing to their high sensitivity, ability to perform more thorough staging, and ability to monitor treatment response. This article reviews the current role of PET/computed tomography scanning and PET/MRI in primary malignancies of bone, with an emphasis on imaging characteristics, clinical usefulness, and current limitations.

Intralesional vs. extralesional procedures for low-grade central chondrosarcoma: a systematic review of the literature

INTRODUCTION

Chondroid lesions are very common bone tumors. In most cases, they are benign enchondromas (EC) and, in a minor percentage, chondrosarcomas (CSs), the malignant counterpart. In the latter cases, surgery is the mainstay treatment, because they are chemo- and radio-resistant unless dedifferentiation occurs. If resection is recognized as the gold standard for intermediate-, high-grade tumors, and for low-grade chondrosarcoma (LG-CS) located in the spine and pelvis to reduce the risk of local recurrence, there is still no consensus in literature on the treatment of central low-grade chondrosarcoma (cLG-CS) located in the limbs. Our aim is to perform a review of literature on evidence supporting this approach or not.

MATERIALS AND METHODS

An electronic research of the medical archives was carried out in March 2017 seeking papers evaluating the results of curettage and resection in cLG-CS.

RESULTS

We selected 13 studies corresponding to our criteria. Unfortunately, they were descriptive, retrospective, non-randomized studies. We identified a population of 471 patients for a total of 473 low-grade chondrosarcomas. Two hundred and ninety-nine lesions were treated with curettage and 174 with wide surgery. The two groups were not homogeneous for diagnosis, size and staging, so no comparison between resection and curettage was possible. The global weighted average percentage of local recurrence was 6.7% (20 cases) and 10.9% (19 cases) after curettage and resection, respectively. No cases of metastasis were reported in the group treated with intralesional surgery, compared to five cases reported in the group treated with resection. Indications for surgery were given in most cases based on symptoms and imaging.

CONCLUSIONS

The absence of a preoperative histological diagnosis and the lack of a scientific method to conduct the studies do not sufficiently support curettage for low-grade chondrosarcomas. In the absence of this, resection must be considered a general rule for every malignancy. In our opinion, based on the low biological growth rate of low-grade chondrosarcoma, every chondromatous lesion can be followed-up. Biopsies must be performed based on clinical and radiological suspicions such as pain, scalloping or increase in size, rather than on performing a PET scan to evidence more informative high metabolic areas.

How to Diagnose Enchondroma, Bone Infarct, and Chondrosarcoma

Enchondromas are among the most common benign tumors seen in the skeleton. They are encountered frequently in routine clinical practice. The purpose of this review is to help radiologists confidently diagnose enchondroma and distinguish it from other entities, such as bone infarct, bone graft, and low-grade chondrosarcoma.

Surgical Management of Medically Refractory Tietze Syndrome

Tietze syndrome is a rare and benign cause of chest pain that may be confused with life-threatening conditions. Characteristic findings are painful, localized inflammation of the costosternal, sternoclavicular, or costochondral joints typically of the second and third ribs. We present a patient with severe, medically refractory symptoms consistent with Tietze syndrome. Although surgical management is not the typical treatment course, symptomatic control was eventually achieved with complete resection of the involved cartilage and adjacent rib. We propose surgical management in patients with debilitating cases of Tietze syndrome that are resistant to conservative therapies.

F-18 FDG PET differentiation of benign from malignant chondroid neoplasms: a systematic review of the literature

INTRODUCTION

Discriminating among benign chondroid tumors, low-grade chondrosarcomas, and grade 2/3 chondrosarcomas is frequently difficult with standard imaging modalities. We systematically reviewed the literature to determine the performance of PET-CT in making this distinction.

METHODS

A systematic review was performed identifying 811 PubMed- and Embase-indexed articles containing combinations of "chondrosarcoma," "enchondroma," "chondroid," "cartilage" and "PET/CT," "PET," "positron." Eight articles including 166 lesions were included. Age, gender, tumor size, histologic grade, and SUVmax values were extracted for individual lesions when possible and otherwise recorded as aggregated data. Comparisons in SUVmax among benign, low-grade, and intermediate-/high-grade chondroid neoplasms were made.

RESULTS

Individual SUVs were available for 101 lesions; 65 additional lesions were reported as aggregated data. There were 101 malignant and 65 benign tumors. Benign tumors were seen more frequently in females (p = 0.04, Fischer's exact test), but malignancy was not associated with age or lesion size. SUVmax was lower for benign (1.6 ± 0.7) than malignant tumors (4.4 ± 2.5) (p < 0.0001, t-test). SUVmax was lower for grade 0/1 (2.0 ± 0.7) than grade 2/3 (6.0 ± 3.2) (p < 0.0001, t-test). Increasing SUVmax correlated with higher grade chondroid tumors (Spearman's rank, ρ = 0.78). SUVmax ≥4.4 was 99% specific for grade 2/3 chondrosarcoma.

CONCLUSIONS

SUVmax correlates with histologic grade in intraosseous chondroid neoplasms; very low SUVmax supports a diagnosis of benign tumor, while elevated SUVmax is suggestive of higher grade chondrosarcoma.

Do Orthopaedic Oncologists Agree on the Diagnosis and Treatment of Cartilage Tumors of the Appendicular Skeleton?

BACKGROUND

Distinguishing a benign enchondroma from a low-grade chondrosarcoma is a common diagnostic challenge for orthopaedic oncologists. Low interrater agreement has been observed for the diagnosis of cartilaginous neoplasms among radiologists and pathologists, but, to our knowledge, no study has evaluated inter- and intraobserver agreement among orthopaedic oncologists grading these lesions using initial clinical and imaging information. Determining such agreement is important since it reflects the certainty in the diagnosis by orthopaedic oncologists. Agreement also is important as it will guide future treatment and prognosis, considering that there is no gold standard for diagnosis of these lesions.

QUESTIONS/PURPOSES

(1) to determine inter- and intraobserver agreement among a multinational panel of expert orthopaedic oncologists in diagnosing cartilaginous neoplasms based on their assessment of clinical symptoms and imaging at diagnosis. (2) To describe the most important clinical and imaging features that experts use during the initial diagnostic process. (3) To determine interobserver agreement for proposed initial treatment strategies for cartilaginous neoplasms by this panel of evaluators.

METHODS

Thirty-nine patients with intramedullary cartilaginous neoplasms of the appendicular skeleton of various histopathologic grades were selected and classified as having benign, low-grade malignant, or intermediate- or high-grade malignant neoplasms by 10 experienced orthopaedic oncologists based on clinical and imaging information. Additionally, they chose the three most important clinical or imaging features for the diagnosis of these neoplasms, and they proposed a treatment strategy for each patient. The Kappa coefficient (κ) was used to determine inter- and intraobserver agreement.

RESULTS

Inter- and intraobserver agreements were only fair to good, κ = 0.44(95% CI, 0.41-0.48) and κ = 0.62 (95% CI, 0.52-0.72), respectively. The three factors most frequently identified as helpful in making the diagnosis by our panel were cortical involvement in 65% of evaluations (253/390), neoplasm size in 51% (198/390), and pain in 50% (194/390). The interobserver agreement for the proposed initial treatment strategy after diagnosis was poor (κ = 0.21; 95% CI, 0.18-0.24).

CONCLUSIONS

This study showed barely fair interobserver and fair to good intraobserver agreement for grading of intramedullary cartilaginous neoplasms by orthopaedic oncologists using initial clinical and imaging findings. These results reflect the insufficient guidance interpreting clinical and imaging features, and the limitations of the systems we use today when making these diagnoses. In the same way, they generate concern for the implications that this may have on different treatment strategies and the future prognosis of our patients. Future studies should build on these observations and focus on clarifying our criteria of diagnosis so that treatment recommendations are standardized regardless of the treating institution or oncologist.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Role of diffusion-weighted imaging in skull base lesions: A pictorial review

Skull base lesions can be related to wide number of pathologies including infections, benign and malignant tumors. Accurate diagnosis and differentiation between these entities is important for prompt and appropriate treatment. However, computed tomography and routine magnetic resonance imaging techniques only provide information on the extent of the lesions, with limited ability to differentiate between benign and malignant lesions. Diffusion-weighted imaging can help in many such situations by providing additional information, including help in differentiating benign from malignant lesions, so that appropriate treatment can be initiated. In this review article, we illustrate the imaging findings of the spectrum of skull base lesions, emphasizing the role of diffusion-weighted imaging in this domain.

Pictorial review of 18F-FDG PET/CT findings in musculoskeletal lesions

We herein reviewed ¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) findings in a number of musculoskeletal lesions including malignant tumors, benign tumors, and tumor-like lesions with correlations to other radiographic imaging modalities, and described the diversity of the ¹⁸F-FDG PET/CT findings of this entity. Malignant primary musculoskeletal tumors are typically ¹⁸F-FDG avid, whereas low-grade malignant tumors show mild uptake. Benign musculoskeletal tumors generally show a faint uptake of ¹⁸F-FDG, and tumor-like conditions also display various uptake patterns of ¹⁸F-FDG. Although musculoskeletal tumors show various uptakes of ¹⁸F-FDG on PET/CT, its addition to morphological imaging modalities such as CT and MRI is useful for the characterization and differentiation of musculoskeletal lesions.

Costal chondrosarcoma requiring differential diagnosis from metastatic tumor

Although chondrosarcoma is a common malignant bone tumor, cases arising in the rib are relatively rare. We experienced a case of chondrosarcoma arising in the right 10th rib during follow-up after lung cancer surgery. Although the finding of an osteolytic mass suggested a metastatic bone tumor, 18F-fluorodeoxyglucose positron-emission tomography demonstrated low fluorodeoxyglucose uptake, and a primary bone tumor was suspected. The bone tumor was resected and diagnosed as chondrosarcoma. Four years after resection, there has been no recurrence or metastasis. Positron-emission tomography was useful for differential diagnosis between a chondrosarcoma and a metastatic bone tumor.