Normal Bone Marrow and Non-neoplastic Systemic Hematopoietic Disorders in the Adult.

This article provides an overview of the imaging appearances of normal adult bone marrow with an emphasis on magnetic resonance imaging. We also review the cellular processes and imaging features of normal developmental yellow-to-red marrow conversion and compensatory physiologic or pathologic red marrow reconversion. Key imaging features that differentiate between normal adult marrow, normal variants, non-neoplastic hematopoietic disorders, and malignant marrow disease are discussed, as well as posttreatment changes.

Skip metastases in appendicular Ewing sarcoma: relationship to distant metastases at diagnosis, chemotherapy response and overall survival.

OBJECTIVE: To identify in appendicular Ewing sarcoma (ES), if skip metastases (SM) are associated with distant metastases at presentation, response to neoadjuvant chemotherapy and overall outcome. MATERIALS AND METHOD: Patients with appendicular ES from 2007 to 2021 who had whole-bone MRI to identify SM were included in the study. Patient demographics included age/gender, bone involved, the presence of SM, longitudinal tumour length, presence of extra-osseous disease and its axial depth if present from whole-bone MRI and lung metastases and distant bone metastases from staging studies. Response to neoadjuvant chemotherapy from resection specimens and overall survival were noted. Comparison of these factors between patients with and without SM was undertaken. RESULTS: Ninety-five patients (66 males; 29 females: mean age 15.8 years; range 5-48 years) were included. On whole-bone MRI, 80 (84.2%) patients had no SM and 15 (15.8%) patients had one or more SM. Of patients without a SM, lung metastases were present in 16 (21%), distant bone metastases in 7 (11%), while 51 (75%) had a good response to chemotherapy compared with 7 (50%), 3 (27%), and 10 (77%), respectively, in patients with a SM. SM were significantly associated with lung metastases (p = 0.02), but not with distant skeletal metastases (p = 0.13), chemotherapy response (p = 0.88), tumour length (p = 0.47), presence of (p = 0.15) or axial depth of extra-osseous disease (p = 0.4). SM were associated with a significantly poorer survival (p = 0.007) and three times greater risk of death during follow-up. CONCLUSIONS: In appendicular ES, the identification of a SM is associated with the presence of lung metastases at presentation and poorer survival.

The imaging of cervical spondylotic myeloradiculopathy.

This review provides a detailed description of the imaging features of cervical spondylotic myelopathy and radiculopathy, with a focus on MRI. Where relevant, we will outline grading systems of vertebral central canal and foraminal stenosis. Whilst post-operative appearances of the cervical spine are outside the scope of this paper, we will touch on imaging features recognised as predictors of clinical outcome and neurological recovery. This paper will serve as a reference for both radiologists and clinicians involved in the care of patients with cervical spondylotic myeloradiculopathy.

Extra-skeletal osteosarcoma: a review.

Extra-skeletal osteosarcoma is a rare malignant soft tissue sarcoma which can cause a diagnostic challenge due to its non-specific presentation and soft tissue mineralisation, thus potentially mimicking conditions such as myositis ossificans. This review will outline the demographics, clinical presentation, key imaging features, differential diagnosis, management and outcomes of extra-skeletal osteosarcoma and serve as a reference to radiologists and other clinicians involved in the care of patients with soft tissue tumours and tumour-like lesions.

An update on imaging of tarsal tunnel syndrome.

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the tibial nerve (TN) within the tarsal tunnel (TT) at the level of the tibio-talar and/or talo-calcaneal joints. Making a diagnosis of TTS can be challenging, especially when symptoms overlap with other conditions and electrophysiological studies lack specificity. Imaging, in particular MRI, can help identify causative factors in individuals with suspected TTS and help aid surgical management. In this article, we review the anatomy of the TT, the diagnosis of TTS, aetiological factors implicated in TTS and imaging findings, with an emphasis on MRI.

Update on imaging of the cervical spine in rheumatoid arthritis.

Rheumatoid arthritis is a multisystem, autoimmune, inflammatory disorder with numerous musculoskeletal manifestations. Involvement of the cervical spine is common and may result in severe complications due to synovitis, erosions, pannus formation, spinal instability and ankylosis. The purpose of this article is to review the current role of imaging in the rheumatoid spine, with emphasis on radiographs and MRI.

Malignant giant cell tumour of bone: a review of clinical, pathological and imaging features.

Giant cell tu mour accounts for up to 5% of all bone tumours and malignant giant cell tumour arises in < 10% of cases, representing sarcomatous transformation. Primary malignant giant cell tumour of bone occurs when sarcomatous tissue is observed within conventional giant cell tumour histologically on initial presentation. Secondary malignant giant cell tumour of bone occurs in a region of previously treated giant cell tumour, with most cases arising due to prior radiotherapy. Malignancy in giant cell tumour of bone does not have any unique clinical or imaging features compared to conventional aggressive disease. Historically, malignant giant cell tumour of bone has a poor prognosis which is worse in cases of secondary malignancy. This article aims to present the clinical, pathological and imaging features of MGCTB based on a review of the literature and illustrated by examples from our experience.

Update on the imaging features of the enchondromatosis syndromes.

Ollier disease and Maffucci syndrome are the commonest enchondromatosis subtypes, arising from non-hereditary mutations in the IDH1 and IDH2 genes, presenting in childhood and being characterised by multiple enchondromas. Maffucci syndrome also includes multiple soft tissue haemangiomas. Aside from developing bony masses, osseous deformity and pathological fracture, ~ 40% of these patients develop secondary central chondrosarcoma, and there is increased risk of non-skeletal malignancies such as gliomas and mesenchymal ovarian tumours. In this review, we outline the molecular genetics, pathology and multimodality imaging features of solitary enchondroma, Ollier disease and Maffucci syndrome, along with their associated skeletal complications, in particular secondary chondrosarcoma. Given the lifelong risk of malignancy, imaging follow-up will also be explored. Metachondromatosis, a rare enchondromatosis subtype characterised by enchondromas and exostoses, will also be briefly outlined.

Peripheral and periosteal chondrosarcoma: MRI-pathological correlation in 58 cases.

OBJECTIVE: To determine whether MRI can distinguish atypical cartilaginous tumour/grade 1 peripheral/periosteal chondrosarcoma (ACT/Gd1 PP-CS) from high-grade peripheral/periosteal chondrosarcoma (HG-PP-CS) or dedifferentiated peripheral/periosteal chondrosarcoma (DD-PP-CS). MATERIALS AND METHODS: Retrospective review of patients diagnosed between January 2007 and December 2020 who had undergone resection of PP-CS. Data collected included age, sex, and skeletal location. Histological tumour grades based on surgical resection were classified as ACT/grade 1 PP-CS, HG-PP-CS, or DD-PP-CS. A variety of MRI features were reviewed independently by 2 musculoskeletal radiologists blinded to final diagnosis and compared between the 3 groups. For statistical analysis, HG-PP-CS and DD-PP-CS were combined. RESULTS: Fifty-eight patients fulfilled the inclusion criteria, 31 (53%) males and 27 (47%) females with a mean age at diagnosis of 46.1 years (range 11-83 years), 14 (24%) of whom had an underlying diagnosis of diaphyseal aclasis. Forty-one (70.7%) cases were peripheral and 17 (29.3%) periosteal, 38 (66%) involving the flat bones, 15 (26%) the major long bones, 3 (5%) the spine, and 2 (3%) the bones of the hands and feet. Final histology revealed 33 (57%) ACT/Gd1-PP-CS, 18 (31%) HG-PP-CS, and 7 (12%) DD-PP-CS. Periosteal tumours were 16 times more likely to be HG/DD-CS compared to peripheral tumours (p < 0.001). Intra-medullary tumour extension was predictive of HG/DD-CS (p = 0.004) for both tumour types, while cap thickness (p = 0.04) and a diffuse cap type (p = 0.03) were differentiating features of low-grade and high-grade peripheral CS. DISCUSSION: A variety of features can help differentiate low-grade from high-grade peripheral/periosteal CS, the most significant being origin from the bone surface.

The value of re-staging chest CT at first local recurrence of extremity and trunk soft tissue sarcoma.

OBJECTIVE: To determine the prevalence of pulmonary metastases on re-staging chest CT at the time of first local recurrence (LR) of trunk or extremity soft tissue sarcoma (STS). MATERIALS AND METHODS: Retrospective review of all patients diagnosed with recurrent STS between May 2007 and April 2018. Data collected included patient age and sex, site of primary STS, time to LR, recurrence site, initial tumour grade, recurrent tumour grade, findings of initial staging chest CT, and prevalence of pulmonary metastases on re-staging chest CT. RESULTS: The study included 109 patients (males = 68, females = 41; mean age 56 years, range 9-92 years). The commonest tumour sub-types were myxofibrosarcoma (27.5%), undifferentiated pleomorphic/spindle cell sarcoma (20.2%), synovial sarcoma (10.1%), and malignant peripheral nerve sheath tumour (10.1%). Initial staging chest CT demonstrated pulmonary metastases in 1 of 77 (1.3%) patients for whom CT was available for review. The mean time to LR was 30.8 months (range 3-224 months). Pulmonary metastases were diagnosed on re-staging chest CT in 26 of 109 cases (23.9%), being commonest with grade 3 STS (36.1%). Pleomorphic sarcoma (85.7%) and undifferentiated spindle cell sarcoma (33.3%) were the 2 commonest tumour sub-types associated with pulmonary metastases at first LR. CONCLUSION: Re-staging chest CT at the time of first LR of STS identified a prevalence of 23.9% pulmonary metastases, which supports the need for chest CT at the time of LR in line with the UK guidelines for the management of bone and soft tissue sarcoma. KEY POINTS: • Pulmonary metastases were diagnosed in 1.3% of soft tissue sarcomas at presentation. • Pulmonary metastases were identified in ~ 24% of patients at first local recurrence of soft tissue sarcoma, most commonly with pleomorphic sarcoma and Trojani grade tumours. • No patient with a low-grade recurrence had pulmonary metastases.

An update on imaging of Paget's sarcoma.

Paget's sarcoma is a rare and particularly aggressive tumour arising within pagetic bone, affecting approximately 1% of patients with Paget's disease during the course of their disease. Most of these tumours are osteosarcomas, but the age profile, skeletal distribution and clinical outcomes differ considerably from conventional osteosarcoma. In this review, we outline the clinical, radiographic/CT, scintigraphic and magnetic resonance imaging features of Paget's sarcoma. We also review the neoplastic and non-neoplastic mimics of Paget's sarcoma that should be considered in the differential diagnosis when encountering an aggressive lesion within pagetic bone.

Telangiectatic soft tissue sarcoma and chronic expanding haematoma: a comparative review of MRI features.

Soft tissue sarcomas containing a dominant component of haemorrhage are known to be aggressive tumours associated with a poor prognosis. Importantly, the clinical behaviour and imaging characteristics of extensively haemorrhagic soft tissue sarcomas (also termed telangiectatic soft tissue sarcomas) can resemble those of benign haematomas, particularly those that continue to expand over a prolonged period, so-called chronic expanding haematomas (CEH). The following review evaluates the current literature to identify the clinical, imaging and pathological characteristics of telangiectatic soft tissue sarcomas and to determine features that may help distinguish them from CEH. Ultimately, we suggest that lesions with sizeable regions of internal haemorrhage should be regarded with a high degree of suspicion for underlying malignancy and require referral to a tertiary sarcoma centre, where a carefully planned approach to biopsy and follow-up is needed to avoid errors in diagnosis.

The rare primary bone sarcomas: imaging-pathological correlation.

Rare primary bone sarcomas are challenging entities both radiologically and pathologically. These include the diagnoses of spindle cell sarcoma (leiomyosarcoma, fibrosarcoma, synovial sarcoma, and malignant peripheral nerve sheath tumor), pleomorphic liposarcoma, and undifferentiated pleomorphic sarcoma. The radiographic and cross-sectional imaging features of each of these tumors are presented, along with current key pathological concepts. Frequently non-specific, the radiological appearances must be correlated with all clinical and pathological information available to enable an accurate diagnosis.

Imaging of bone and soft tissue BCOR-rearranged sarcoma.

With recent advances in molecular research, an ever-increasing number of undifferentiated round cell sarcomas without the characteristic gene fusions of Ewing sarcoma are being discovered. One specific subtype termed BCOR-rearranged sarcoma belongs to this group. Previously termed 'Ewing-like' sarcoma, it was formally included with undifferentiated round cell tumours in the 2013 WHO Classification of Soft Tissue and Bone Tumours. However, in the 2020 WHO Classification, BCOR-sarcoma is now recognized as a distinct entity due to particular morphological and immunohistochemical features and differing clinical outcomes. As with classical Ewing sarcoma, osseous BCOR-rearranged sarcoma is an aggressive tumour with a similar clinical presentation. However, there are only a small handful of case series and isolated reports detailing the imaging characteristics, typically demonstrating an aggressive bone lesion with a large soft tissue mass. Soft tissue BCOR-sarcoma is even rarer. The aim of the current review is to describe the patient demographics, lesion locations and various imaging characteristics of histologically proven cases of musculoskeletal bone and soft tissue BCOR-sarcoma as described in the literature.

Multimodality imaging of the paediatric flatfoot.

Flatfoot is commonly encountered in the paediatric population and describes a spectrum of clinical and radiological presentations which encompass both normally developing and pathological feet. Flatfoot can be categorised as flexible or rigid, a distinction which has important implications when considering the potential underlying aetiology and treatment options, and therefore imaging is an important component of the diagnostic workup. Weight-bearing plain radiographs are established initial investigations, although the significance of a number of the commonly derived quantitative parameters in children remains unclear. CT and MRI are important additional imaging modalities reserved for the investigation of symptomatic cases or those in which an underlying structural abnormality is suspected, rigid flatfoot commonly falling into one of these two categories. We review and illustrate the multimodality imaging of the paediatric flatfoot, with reference to both qualitative and quantitative radiographic assessment and cross-sectional imaging appearances.

Imaging following surgery for primary appendicular bone tumours.

Primary bone tumours are uncommon, with sarcomas accounting for < 0.2% of all malignancies. The survival rate of primary bone sarcomas has significantly improved due to (neo)adjuvant therapy, while improved surgical techniques and development of new prostheses have shifted the surgical focus from amputation to limb preservation in the vast majority of patients. A wide variety of surgical options are available for the treatment of primary bone tumours which depend upon histological diagnosis, their appearance at the time of presentation and response to any (neo)adjuvant therapy as required. This review is intended to help radiologists familiarise themselves with the management of primary appendicular bone tumours and expected normal postoperative appearances for the various surgical techniques, and to recognise potential complications.

A review of imaging of surface sarcomas of bone.

Surface lesions of bone are uncommon. Although their imaging features generally mirror those of their intramedullary counterparts, surface lesions may demonstrate distinct characteristics which along with their unusual location present a diagnostic challenge. Surface sarcomas are usually of a lower grade compared with intramedullary variants, leading to differences in management. Osteosarcoma arising from the cortical surface of the bone is termed juxtacortical or surface osteosarcoma and includes three distinct entities: parosteal, periosteal, and high-grade surface osteosarcoma. We also review the features intracortical osteosarcoma, which some authors include under the umbrella term surface osteosarcoma. These lesions exhibit biologic features distinct from those of conventional intramedullary osteosarcoma, which underlines the importance of accurate imaging diagnosis. Periosteal chondrosarcoma and periosteal Ewing sarcoma also have distinctive imaging appearances. The purpose of this article is to review surface sarcomas of bone with regard to their clinical and radiological features and to discuss the differential diagnosis for each condition.

The value of chest and skeletal staging studies in conventional chondrosarcoma.

OBJECTIVE: To determine the value of chest and skeletal staging in patients presenting with conventional chondrosarcoma (CS). MATERIALS AND METHODS: Retrospective review of patients with CS diagnosed between January 2007 and December 2019. Data collected included age, sex, skeletal location and results of chest CT and whole-body bone scintigraphy (WB-BSc) obtained at initial diagnosis. The histological tumour grade based on surgical resection or needle biopsy was classified as low-grade (LGCT), high-grade (HGCT) and dedifferentiated (DD-CS). Findings of chest CT and WB-BSc were correlated with tumour grade. RESULTS: Four hundred twenty patients were included (234 males and 186 females with mean age 54.5 years, range 9-91 years). The major long bones were involved in 205 cases, the flat bones in 166 cases, the mobile spine in 14 cases and the small bones of the hands and feet in 35 cases. Three hundred fifty tumours were central in location, 39 peripheral and 31 on the surface of the bone. There were 151 LGCTs, 196 HGCTs and 73 DD-CSs. Of patients with LGCT, 41.7% underwent chest CT and 25.2% WB-BSc. Of patients with HGCT, 95.4% underwent chest CT and 76.5% WB-BSc. Of patients with DD-CS, 98.6% underwent chest CT and 86.3% WB-BSc. Metastases were diagnosed in 2 (3.3%) chest CT studies and 0 WB-BSc in LGCT, in 8 (4.3%) chest CT studies and 0 WB-BSc in HGCT and in 21 (30%) chest CT studies and 6 (21%) WB-BSc in DD-CS. DISCUSSION: Staging chest CT and WB-BSc is of little or no value except in DD-CS.

An accessory iliotibial band insertion: a unique anatomical variant.

The iliotibial band (ITB) is considered an important anterolateral knee joint stabiliser. Its exact anatomy remains unclear with inconsistency owing to relative paucity of detailed cadaveric studies. Multiple ITB distal insertional sites have been reported, the most common and well known being a direct attachment onto Gerdy's tubercle of the anterolateral tibia. We report a rare distal insertional site not previously documented. A 50-year-old man presented with anterior knee pain. MRI showed an accessory band deep to the ITB, partially blending in with its superficial fibres. It inserted onto the anterolateral tibial tuberosity, deep to the patellar tendon insertion and inferomedial to Gerdy's tubercle. This was asymptomatic but the patient did have an underlying median patella ridge osteochondral defect successfully treated with stem cell grafting, completely unrelated to the mentioned variant. This case highlights the importance of detecting rare anatomical variants which can potentially be a source of lateral knee pain.

Skip metastases in high-grade intramedullary appendicular osteosarcoma: an indicator of more aggressive disease?

OBJECTIVE: To determine whether skip metastases (SM) in high-grade appendicular osteosarcoma (HG-OS) are an indicator of more aggressive disease. MATERIALS AND METHOD: Retrospective review of patients with histologically confirmed diagnosis HG-OS of the long bones from 2007 to 2020, who had whole-bone MRI to identify SM. Data collected included patient age/gender, bone involved, the presence of SM, the presence of lung metastases from chest CT, the presence of distant bone metastases from whole-body bone scintigraphy or whole-body MRI, and chemotherapy response from resection specimen histology. The presence of lung or bone metastases and chemotherapy response were compared between patients without and with SM. RESULTS: The study included 241 patients (146 males; 95 females: mean age 18.2 years; range 4-73 years). Based on whole-bone MRI, 202 (83.8%) patients had no SM and 39 (16.2%) patients had a SM. Of patients without a SM, lung metastases were identified in 44 (22%) and distant bone metastases in 6 (3%) cases, while 80 (43%) had a good chemotherapy response and 105 (57%) had a poor chemotherapy response. Of patients with a SM, lung metastases were identified in 22 (58%) and distant bone metastases in 8 (21%) cases, while 11 (32%) had a good chemotherapy response and 23 (68%) had a poor chemotherapy response. The presence of SM was significantly associated with both lung metastases (p < 0.001) and skeletal metastases (p < 0.001), but not with chemotherapy response (p = 0.24). Patients with SM also had poorer survival (p < 0.001). CONCLUSIONS: The presence of SM in appendicular HG-OS suggests more aggressive disease.