A retrospective external validation study of the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) for the management of solitary central cartilage tumours of the proximal humerus and around the knee.

OBJECTIVES: This study aimed to externally validate the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) recommendations for differentiation/follow-up of central cartilage tumours (CCTs) of the proximal humerus, distal femur, and proximal tibia and to propose BACTIP adaptations if the results provide new insights. METHODS: MRIs of 123 patients (45 ± 11 years, 37 men) with an untreated CCT with MRI follow-up (n = 62) or histopathological confirmation (n = 61) were retrospectively/consecutively included and categorised following the BACTIP (2003-2020 / Ghent University Hospital/Belgium). Tumour length and endosteal scalloping differences between enchondroma, atypical cartilaginous tumour (ACT), and high-grade chondrosarcoma (CS II/III/dedifferentiated) were evaluated. ROC-curve analysis for differentiating benign from malignant CCTs and for evaluating the BACTIP was performed. RESULTS: For lesion length and endosteal scalloping, ROC-AUCs were poor and fair-excellent, respectively, for differentiating different CCT groups (0.59-0.69 versus 0.73-0.91). The diagnostic performance of endosteal scalloping and the BACTIP was higher than that of lesion length. A 1° endosteal scalloping cut-off differentiated enchondroma from ACT + high-grade chondrosarcoma with a sensitivity of 90%, reducing the potential diagnostic delay. However, the specificity was 29%, inducing overmedicalisation (excessive follow-up). ROC-AUC of the BACTIP was poor for differentiating enchondroma from ACT (ROC-AUC = 0.69; 95%CI = 0.51-0.87; p = 0.041) and fair-good for differentiation between other CCT groups (ROC-AUC = 0.72-0.81). BACTIP recommendations were incorrect/unsafe in five ACTs and one CSII, potentially inducing diagnostic delay. Eleven enchondromas received unnecessary referrals/follow-up. CONCLUSION: Although promising as a useful tool for management/follow-up of CCTs of the proximal humerus, distal femur, and proximal tibia, five ACTs and one chondrosarcoma grade II were discharged, potentially inducing diagnostic delay, which could be reduced by adapting BACTIP cut-off values. CLINICAL RELEVANCE STATEMENT: Mostly, Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP) assesses central cartilage tumours of the proximal humerus and the knee correctly. Both when using the BACTIP and when adapting cut-offs, caution should be taken for the trade-off between underdiagnosis/potential diagnostic delay in chondrosarcomas and overmedicalisation in enchondromas. KEY POINTS: • This retrospective external validation confirms the Birmingham Atypical Cartilage Tumour Imaging Protocol as a useful tool for initial assessment and follow-up recommendation of central cartilage tumours in the proximal humerus and around the knee in the majority of cases. • Using only the Birmingham Atypical Cartilage Tumour Imaging Protocol, both atypical cartilaginous tumours and high-grade chondrosarcomas (grade II, grade III, and dedifferentiated chondrosarcomas) can be misdiagnosed, excluding them from specialist referral and further follow-up, thus creating a potential risk of delayed diagnosis and worse prognosis. • Adapted cut-offs to maximise detection of atypical cartilaginous tumours and high-grade chondrosarcomas, minimise underdiagnosis and reduce potential diagnostic delay in malignant tumours but increase unnecessary referral and follow-up of benign tumours.

Radiofrequency ablation for the treatment of a presumed enchondroma in the flat bones of the pelvis.

Herein, a 30-year-old Caucasian female who presented with a persistent pain in the right pelvic region due to an enchondroma and treated with RF ablation is described. An initial MRI of the pelvis revealed a well-circumscribed lesion in the right inferior ischiopubic ramus with a maximum diameter of 9.5 mm. The final diagnosis was established by a percutaneous CT-guided bone biopsy, which excluded malignancy and revealed an enchondroma. About a month after the biopsy, a percutaneous radiofrequency ablation (RFA) of the lesion was performed. The symptoms resolved completely gradually 2 months after the treatment and a follow-up imaging with MRI showed complete resolution of the pathological enhancement indicating necrosis of the lesion. RFA has not been previously reported as a treatment option of enchondromas found in flat bones of the pelvis and could be a safe alternative minimally invasive treatment option in such cases, avoiding major operations.

Concurrent intraosseous cartilaginous lesions in patients with multiple osteochondromas identified on total-body MR imaging.

PURPOSE: To assess the prevalence of intraosseous cartilaginous lesions in patients with multiple osteochondromas based on total-body (TB) MRI examinations, used for screening purposes. SUBJECTS AND METHODS: Between 2013 and 2020, TB-MRI examinations were performed in 366 patients with proven multiple osteochondromas syndrome, to rule out malignant progression. For this study, presence, or absence of intraosseous central or eccentrical chondroid lesions, defined as lobulated lesions with low signal intensity on T1-weighted images, replacing bone marrow and high signal intensity equal to fluid on T2-weighted images in the bone marrow of the meta-diaphysis of (one of) the long bones, were recorded in the long bones as part of a TB-MRI protocol. RESULTS: In 62 patients out of the 366 MO patients (17%), one or more intraosseous chondroid lesions (either enchondroma or atypical cartilaginous tumor) were detected. The age of the patients at time of diagnosis ranged from 17 to 61 years (mean, 36). Size of the lesions varied from 4 to 69 mm (mean, 16.3 mm). The most common location was the proximal femur (n = 29), followed by the distal femur and proximal humerus (n = 18 and n = 10, respectively). In nine of the patients with an intraosseous chondroid lesion, a second and/or third TB-MRI were available during the period of evaluation (mean interval, 2.7 years between the exams). In none of these patients increase of these intraosseous lesions was noticed. CONCLUSION: Intraosseous chondroid lesions (enchondroma and ACT) appear to occur more frequently in MO patients than in the general population. TB-MRI allows to detect these, besides the identification of OC with suspicious features.

The diagnostic value of magnetic resonance imaging-based texture analysis in differentiating enchondroma and chondrosarcoma.

OBJECTIVE: To assess the diagnostic performance of MRI-based texture analysis for differentiating enchondromas and chondrosarcomas, especially on fat-suppressed proton density (FS-PD) images. MATERIALS AND METHODS: The whole tumor volumes of 23 chondrosarcomas and 24 enchondromas were manually segmented on both FS-PD and T1-weighted images. A total of 861 radiomic features were extracted. SelectKBest was used to select the features. The data were randomly split into training (n = 36) and test (n = 10) for T1-weighted and training (n = 37) and test (n = 10) for FS-PD datasets. Fivefold cross-validation was performed. Fifteen machine learning models were created using the training set. The best models for T1-weighted, FS-PD, and T1-weighted + FS-PD images were selected in terms of accuracy and area under the curve (AUC). RESULTS: There were 7 men and 16 women in the chondrosarcoma group (mean ± standard deviation age, 45.65 ± 11.24) and 7 men and 17 women in the enchondroma group (mean ± standard deviation age, 46.17 ± 11.79). Naive Bayes was the best model for accuracy and AUC for T1-weighted images (AUC = 0.76, accuracy = 80%, recall = 80%, precision = 80%, F1 score = 80%). The best model for FS-PD images was the K neighbors classifier for accuracy and AUC (AUC = 1.00, accuracy = 80%, recall = 80%, precision = 100%, F1 score = 89%). The best model for T1-weighted + FS-PD images was logistic regression for accuracy and AUC (AUC = 0.84, accuracy = 80%, recall = 60%, precision = 100%, F1 score = 75%). CONCLUSION: MRI-based machine learning models have promising results in the discrimination of enchondroma and chondrosarcoma based on radiomic features obtained from both FS-PD and T1-weighted images.

Soft Tissue Chondroma of the Chin.

Soft tissue chondromas are benign tumors, generally of the hands or feet, very rarely of the head and neck region. Repeated microtrauma may be as an initiating factor. The authors describe a case of a soft tissue chondroma of the chin in a 58-year-old male who had used a continuous positive airway pressure face mask for obstructive sleep apnea for 3 years. The patient presented with a hard mass on his chin for 1 year. Computed tomography imaging showed a heterogeneous enhancing mass, with calcification in the subcutaneous layer. Intraoperatively, the mass was beneath the mentalis muscle and abutted the mental nerve, without bone involvement. The diagnosis was a soft tissue chondroma. The patient recovered fully, without recurrence. The primary cause of soft tissue chondromas is unknown. The authors consider that continuous use of a continuous positive airway pressure face mask may play a role in the etiology.

The use of radiomics and machine learning for the differentiation of chondrosarcoma from enchondroma.

PURPOSE: To construct and compare machine learning models for differentiating chondrosarcoma from enchondroma using radiomic features from T1 and fat suppressed Proton density (PD) magnetic resonance imaging (MRI). METHODS: Eighty-eight patients (57 with enchondroma, 31 with chondrosarcoma) were retrospectively included. Histogram matching and N4ITK MRI bias correction filters were applied. An experienced musculoskeletal radiologist and a senior resident in radiology performed manual segmentation. Voxel sizes were resampled. Laplacian of Gaussian filter and wavelet-based features were used. One thousand eight hundred eighty-eight features were obtained for each patient, with 944 from T1 and 944 from PD images. Sixty-four unstable features were removed. Seven machine learning models were used for classification. RESULTS: Classification with all features showed neural network was the best model for both readers' datasets with area under the curve (AUC), classification accuracy (CA), and F1 score of 0.979, 0.984; 0.920, 0.932; and 0.889, 0.903, respectively. Four features, including one common to both readers, were selected using fast correlation based filter. The best performing models with selected features were gradient boosting for Fatih Erdem's dataset and neural network for Gülen Demirpolat's dataset with AUC, CA, and F1 score of 0.990, 0.979; 0.943, 0.955; 0.921, 0.933, respectively. Neural Network was the second-best model for FE's dataset based on AUC (0.984). CONCLUSION: Using pathology as a gold standard, this study defined and compared seven well-performing models to distinguish enchondromas from chondrosarcomas and provided radiomic feature stability and reproducibility among the readers.

Chondroma Arising from the Temporomandibular Joint: A Case Report.

Periarticular chondromas are common in the humerus and femur but rarely occur in the temporomandibular joint. We report a case of a chondroma in the anterior part of the ear. One year prior to his visit, a 53-year-old man became aware of swelling in the right cheek region which gradually increased in size. In the anterior part of the right ear, there was a palpable 25 mm tumor, elastic and hard, with poor mobility and without tenderness. A contrast-enhanced computed tomography CT showed a mass lesion with diffuse calcification or ossification in the upper pole of the parotid gland and areas of poor contrast within. A magnetic resonance imaging showed a low-signal mass lesion at the parotid gland with some high signals in both T1 and T2. Fine-needle aspiration cytology did not lead to diagnosis. Using a nerve monitoring system, the tumor was resected with normal tissue of the upper pole of the parotid gland in the same way as for a benign parotid tumor. Distinguishing between pleomorphic adenoma, including diffuse microcalcification of the parotid gland and cartilaginous tumors of the temporomandibular joint, may be sometimes difficult. In such cases, surgical resection may be a beneficial treatment option.

Assessment of central cartilaginous tumor of the appendicular bone: inter-observer and intermodality agreement and comparison of diagnostic performance of CT and MRI.

BACKGROUND: Diagnostic performance, inter-observer agreement, and intermodality agreement between computed tomography (CT) and magnetic resonance imaging (MRI) in the depiction of the major distinguishing imaging features of central cartilaginous tumors have not been investigated. PURPOSE: To determine the inter-observer and intermodality agreement of CT and MRI in the evaluation of central cartilaginous tumors of the appendicular bones, and to compare their diagnostic performance. MATERIAL AND METHODS: Two independent radiologists retrospectively reviewed preoperative CT and MRI. Inter-observer and intermodality agreement between CT and MRI in the assessment of distinguishing imaging features, including lesion size, deep endosteal scalloping, cortical expansion, cortical disruption, pathologic fracture, soft tissue extension, and peritumoral edema, were evaluated. The agreement with histopathology and the accuracy of the radiologic diagnoses made with CT and MRI were also analyzed. RESULTS: A total of 72 patients were included. CT and MRI showed high inter-observer and intermodality agreements with regard to size, deep endosteal scalloping, cortical expansion, cortical disruption, and soft tissue extension (ICC = 0.96-0.99, k = 0.60-0.90). However, for the evaluation of pathologic fracture, MRI showed only moderate inter-observer agreement (k = 0.47). Peritumoral edema showed only fair intermodality agreement (k = 0.28-0.33) and moderate inter-observer agreement (k = 0.46) on CT. Both CT and MRI showed excellent diagnostic performance, with high agreement with the histopathology (k = 0.89 and 0.87, respectively) and high accuracy (91.7% for both CT and MRI). CONCLUSION: CT and MRI showed high inter-observer and intermodality agreement in the assessment of several distinguishing imaging features of central cartilaginous tumors of the appendicular bones and demonstrated comparable diagnostic performance.

Incidental long bone cartilage lesions: is any further imaging workup needed?

OBJECTIVE: To determine the rate of chondrosarcoma in incidentally discovered painless long bone cartilage lesions and to determine if any further imaging is needed. MATERIALS AND METHODS: A cartilage lesion was said to be an enchondroma when it had characteristic matrix mineralization and no aggressive features. Search of all imaging reports and tumor board files for keywords enchondroma, cartilage lesion, chondroid, and chondrosarcoma. Retrospective review of medical records and imaging studies from 4.5-year period. Data points collected included patient age, sex, lesion site, size, symptoms, type of imaging, imaging appearance, and length of follow-up. Only patients with no pain were included as enchondroma. Patients with final diagnosis of chondrosarcoma were included for comparison of all features. RESULTS: Only 1/73 (1.4%) patients with an initial incidentally discovered painless lesion was later diagnosed, with new symptoms, as atypical cartilage tumor. Average age was 59.4 years. Bones involved were the femur (n = 33), humerus (n = 30), tibia (n = 7), fibula (n = 2), and ulna (n = 1). Average enchondroma size was 3.9 cm (range 1.4-11.5). Average follow-up was 47 months (range 2-196 months). Eleven long bone chondrosarcomas were identified. All chondrosarcoma patients had pain and aggressive imaging findings. CONCLUSION: Our study reveals that the rate of chondrosarcoma in incidentally found painless chondroid lesions without aggressive features in long bones is low. Imaging follow-up may be needed only in the setting of new symptoms.

Acral FibroChondroMyxoid tumor: imaging features of a new entity.

"Acral FibroChondroMyxoid tumor" (AFCMT) is a recently described distinctive subtype of acral soft tissue tumor that typically arises on the fingers and toes. We herein present the unreported imaging features of AFCMT in a 44-year-old woman. This otherwise healthy patient was referred for a painful, slow-growing, soft tissue mass in the middle finger of her right hand. Initial radiographs and computed tomography showed a small lesion centered in the soft tissue of the ulnar aspect of the proximal phalanx, associated with scalloping of the underlying bone. Magnetic resonance imaging confirmed the presence of a well-circumscribed soft tissue tumor that exhibited relatively high T2-weighted signal intensity and marked enhancement after contrast administration. Subsequent excisional biopsy was performed. Histologically, the tumor was characterized by an abundant stroma displaying fibrous, chondroid, and myxoid areas. By immunohistochemistry, tumor cells stained for CD34, ERG, and focally S100 protein. RNA-sequencing allowed detection of THBS1-ADGFR5 gene fusion which confirmed the diagnosis of AFCMT. At 2-year follow-up, the patient remains free of recurrence. AFCMT is a previously unrecognized entity that may mimic chondroma and should be considered in the differential diagnosis of soft tissue tumors with cartilaginous or myxoid stroma in the extremities.

Early Surgical Treatment of Both Tumor and Fracture in Patients With Enchondroma of the Hand Combined With Pathologic Fracture.

PURPOSE: The aims of this study were to evaluate the degree of cortical thinning and the tumor area in simple radiographs in patients with enchondroma of the hand combined with pathologic fracture and to determine the surgical outcome of simultaneous tumor curettage and internal fixation of fracture. METHODS: We enrolled 23 bone lesions of 21 patients diagnosed with enchondroma of the hand. Of them, 9 bone lesions of 8 patients had pathologic fracture. We evaluated the degree of cortical thinning and tumor area in simple radiographs and compared them between patients with and without pathologic fracture. For patients with pathologic fracture, we performed curettage of the tumor through the fracture site and fixed the fracture using K-wires. We then evaluated the clinical outcome of these patients using the visual analog scale to measure pain intensity and Takigawa's criteria 1 year after surgery. RESULTS: There was a significant difference in the degree of cortical thinning between the 2 groups (P < 0.001); however, there was no significant difference in the percentage of tumor area (P = 0.259). The average time from surgery to bony union was 8.5 weeks in patients with pathologic fracture. The patients reported that they could return to their previous activities of daily living within 12 weeks of surgery. The average visual analog scale score was 0.6 at 1 year after surgery, and 6 patients were graded as excellent and 2 as good according to Takigawa's criteria. CONCLUSIONS: Cortical thinning seems to be related to pathologic fracture. Our scoring system for cortical thinning may be helpful in evaluating the risk for pathologic fracture. Early 1-stage surgical treatment for pathologic hand fracture with enchondroma is a very useful method with satisfactory outcomes that could shorten the treatment period.

[CT and Magnetic Resonance Imaging Findings of the Intracranial Extra-cerebral Chondroma:A Case Report].

Intracranial intradural chondroma is a rare disorder,the imaging findings of which have been rarely reported.The current study reported a case of intracranial extra-cerebral chondroma and described the detailed CT and magnetic resonance imaging findings,which would provide valuable imaging evidence for the diagnosis of intracranial extra-cerebral chondroma.

Nonepithelial Tumors of the Larynx: Single-Institution 13-Year Review with Radiologic-Pathologic Correlation.

Nonepithelial tumors of the larynx are rare and represent a minority of all laryngeal neoplasms. Imaging has an important role in the diagnosis, treatment planning, and surveillance of these entities. However, unfamiliarity with these neoplasms can cause diagnostic difficulties for radiologists, especially because many of the imaging findings are nonspecific. By using a systematic approach based on clinical history, patient age and gender, lesion location, endoscopic results, and specific imaging findings, the differential diagnosis can often be narrowed. These tumors typically affect the submucosal layer, so if a tumor has an intact mucosa at endoscopy, a nonepithelial neoplasm is the most likely diagnosis. Nonepithelial tumors of the larynx can arise from the laryngeal cartilage or muscle or from the surrounding lymphoid tissue or blood vessels. Consequently, imaging findings typically correspond to the specific cell type from which it originated. Recognizing specific features (eg, metaplastic bone formation, macroscopic fat, or enhancement pattern) can often help narrow the differential diagnosis. In addition, identification of noncircumscribed borders of the lesion and invasion of the adjacent structures is key to diagnosis of a malignant process rather than a benign neoplasm. Understanding the pathologic correlation is fundamental to understanding the radiologic manifestations and is ultimately crucial for differentiation of nonepithelial laryngeal neoplasms. Online supplemental material is available for this article. ©RSNA, 2020.

Are the tubular bones of the hand really the commonest site for an enchondroma?

AIM: To investigate whether the long-held view that the hand is the commonest site for an enchondroma is actually correct in light of more sensitive imaging techniques that are able to demonstrate small enchondromas at other skeletal sites. MATERIALS AND METHODS: A two-part retrospective study was undertaken. Part 1 comprised a review of the hand radiographs obtained in two major teaching hospitals over a 10-year period to establish the incidence of enchondroma in the hand. Part 2 was a review of a series of enchondromas of the proximal humerus, distal femur, and proximal tibia <4 cm in length on magnetic resonance imaging (MRI) to see which cases were visible or not on corresponding radiographs. RESULTS: Part 1: 84 enchondromas were identified on 116,354 trauma radiographs to give an incidence of 0.07%. Part 2: 157 patients with an enchondroma on MRI <4 cm were reviewed. Only 17% of lesions <2 cm in length were visible on the contemporaneous radiographs. In lesions that were 2-2.9 and 3-3.9 cm the percentage visible on the radiographs increased to 58 and 77%, respectively. CONCLUSION: It is well recognised from existing studies that incidental enchondromas can be seen in approximately 2.5% of routine shoulder and knee MRI scans. This figure is 35 times higher than the incidence found in the series of hand trauma radiographs. This infers that the hand should no longer be considered as the commonest site for an enchondroma. This is because radiographs are relatively insensitive to the detection of small lesions in larger bones, such as the proximal humerus and around the knee, when compared with MRI.

Chondroma in the Area of the Spheno-Ethmoid Junction.

Chondroma in the area of the spheno-ethmoidal junction is very rare. A 29-year-old male patient with chronic rhinosinusitis with nasal polyps was arranged for a preoperative computed tomography scan, and a lesion was accidentally found in his spheno-ethmoidal junction and involved the skull base. Combined with MRI, the lesion was misdiagnosed as fungal sinusitis. However, no fungal lesions were found during the operation, and cartilage tissue was confirmed only after some bone was ground away under the guidance of a surgical navigation system. Our case indicates that chondroma is easily misdiagnosed as fungal sinusitis when it appears in the sinuses and should be carefully distinguished from fungal sinusitis. Moreover, when lesions involve the skull base, surgical navigation systems are useful in accurately locating lesions.

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.

Can MRI differentiate between atypical cartilaginous tumors and high-grade chondrosarcoma? A systematic review.

Background and purpose - Adequate staging of chondroid tumors at diagnosis is important as it determines both treatment and outcome. This systematic review provides an overview of MRI criteria used to differentiate between atypical cartilaginous tumors (ACT) and high-grade chondrosarcoma (HGCS).Patients and methods - For this systematic review PubMed and Embase were searched, from inception of the databases to July 12, 2018. All original articles describing MRI characteristics of pathologically proven primary central chondrosarcoma and ACT were included. A quality appraisal of the included papers was performed. Data on MRI characteristics and histological grade were extracted by 2 reviewers. Meta-analysis was performed if possible. The study is registered with PROSPERO, CRD42018067959.Results - Our search identified 2,132 unique records, of which 14 studies were included. 239 ACT and 140 HGCS were identified. The quality assessment showed great variability in consensus criteria used for both pathologic and radiologic diagnosis. Due to substantial heterogeneity we refrained from pooling the results in a meta-analysis and reported non-statistical syntheses. Loss of entrapped fatty marrow, cortical breakthrough, and extraosseous soft tissue expansion appeared to be present more often in HGCS compared with ACT.Interpretation - This systematic review provides an overview of MRI characteristics used to differentiate between ACT and HGCS. Future studies are needed to develop and assess more reliable imaging methods and/or features to differentiate ACT from HGCS.

Differential diagnosis and treatment of enchondromas and atypical cartilaginous tumours of the pelvis: analysis of 21 patients.

INTRODUCTION: Studies focusing on enchondroma and atypical cartilaginous tumour (ACT) of the pelvis are lacking. The purpose of this study was to verify possible clinical and radiological findings with regard to distinguishing enchondromas from ACT of the pelvis. In addition, this study analysed functional and oncological outcomes in patients with enchondromas or ACT of the pelvis treated with curettage or resection. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 21 patients with confirmed enchondroma or ACT of the pelvis treated by curettage or resection from 1985 to 2018. The minimum follow-up was 18 months. The relationship between clinical and radiological factors and tumour type or local recurrence was assessed using Fisher exact test and Mann-Whitney U test. RESULTS: Endosteal scalloping (p = 0.039), tumour size (0.005) and age (0.006) were shown to statistically favour ACT over enchondroma; by contrast, enchondroma and ACT patients had no difference in pain frequency (p = 0.5528). All patients with enchondroma had no local recurrence; in contrast, local recurrence occurred in one patient with ACT, initially treated with resection. The patient with local recurrence had a disease progression with a higher histological grade than the original tumour. Patients treated with curettage had better functional outcomes than patients treated with resection (p = 0.001). DISCUSSION: Endosteal scalloping, tumour size and age could be helpful in the differential diagnosis between enchondroma and ACT of the pelvis. In addition, our study showed that ACT of the pelvis can be safely treated with curettage due to a low risk of local recurrence and better functional results compared with resection. In case of recurrence, we suggest to treat these patients with resection for the risk of disease progression.

The incidence and outcome of chondral tumours as incidental findings on investigation of shoulder pathology.

PURPOSE: The aim of this study is to describe outcomes of incidental chondral tumours in the shoulder referred to our Bone Tumour Unit (BTU). METHODS: Our hospital radiology database was searched using the filtered terms "enchondroma", "low-grade chondral tumour", "chondrosarcoma" with "humerus", "arm", "shoulder", "scapula" and "clavicle". Case note review of results assessed primary reasons for referral, radiological diagnosis, recommended management with subsequent reviews and outcomes, either in clinic or surveillance scan reports. RESULTS: Ninety-nine patients had full case note review, mean age 54.5 years (range 18-84 years). Mean follow-up was 41.7 months (range 1-265 months). Over 50% of patients were referred for shoulder pain. Three patients had high-grade chondrosarcoma. Forty-three patients had interval scans, none showing any changes. Thirty-five patients had surgery for their lesions with one recurrence. Forty-four patients had alternative diagnoses made on clinical and radiological examination. At most recent follow-up, 70% of these patients were asymptomatic after physiotherapy/surgical attention to their alternative diagnoses. CONCLUSIONS: Chondral lesions in the shoulder have low risk of malignant transformation and are rarely responsible for shoulder symptoms. We recommend patients be referred to a dedicated BTU for surveillance if there are any concerning features, but to proceed with management for any alternative diagnosis.

A retrospective validation of an imaging protocol for the management of solitary central cartilage tumours of the proximal humerus and around the knee.

AIM: To validate an imaging protocol for the management of solitary central cartilage tumours (CCTs) of the proximal humerus and around the knee. MATERIALS AND METHODS: Over a 10-year period, 387 patients were identified with a CCT in the proximal humerus, distal femur, and proximal tibia, who were referred to a single unit either from primary/secondary care or tertiary care directly to Royal Orthopaedic Hospital, a specialist orthopaedic oncology service. The initial magnetic resonance imaging (MRI) images and any follow-up images were evaluated for length of tumour, presence/absence of endosteal scalloping, or aggressive/malignant features. The cases were categorised into one of seven types according to the Birmingham Atypical Cartilage Tumour Imaging Protocol (BACTIP). The outcome in the cases was assessed to ascertain if application of the protocol would have led to any delay in the diagnosis of malignant transformation to a chondrosarcoma. RESULTS: The incidence of malignancy (chondrosarcoma) increased with ascending BACTIP. There was a 100% benign diagnosis (enchondroma) in types IA and IB, 96% in IIA, and 83% in IIB. Fifty-seven percent of type IIC and 97% type III were diagnosed as malignant. In only one case would the application of the protocol have led to a 5-month delay in the diagnosis of chondrosarcoma. CONCLUSIONS: This retrospective study confirms the BACTIP as a useful tool for the general radiologist in the initial assessment of CCT in the proximal humerus and around the knee with the exception of the proximal fibula. In particular, determining which cases need prompt referral to a specialist orthopaedic oncology service for further assessment.