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To review the clinical and imaging findings of patients with remote history of intramuscular (IM) in vitro fertilization (IVF) gluteal injections, presenting with signs and symptoms of a possible gluteal soft tissue sarcoma. Retrospective review of consecutive patients with a history of prior IVF therapy referred for MRI evaluation of a gluteal soft tissue mass was performed. Six patients were reviewed, with 5 patients meeting study inclusion criteria. Imaging exams (ultrasound n = 3, MRI n = 5) were assessed for lesion location, morphology, and intrinsic imaging characteristics. One case proceeded to percutaneous biopsy with histopathologic correlation. Average patient age was 43 years (range 38–50). Mean time interval between IVF IM injections and MRI was 5.7 years (range 2.2–13 years). Clinical findings included palpable gluteal mass (5/5) and local pain (4/5). Ultrasound showed heterogeneous subcutaneous lesions with varying complex cystic/solid internal echogenicity. On MRI, each case illustrated an irregularly marginated lesion, mean maximal dimension 3.5 cm (range 1.5–5.9 cm), within the deep gluteal subcutaneous fat composed of solitary (1/5) or multifocal (4/5) lobules demonstrating internal areas of high T1 and homogeneous low T2 fat suppressed signal with surrounding peripheral reticular high T2 signal. Correlative histological assessment showed central areas with features of fat necrosis and a peripheral inflammatory rim. In the setting of prior IVF therapy, imaging features of an irregularly marginated, deep subcutaneous gluteal lesion with inflammatory soft tissue changes surrounding solitary or multifocal areas of loculated fat signal may be seen as an inflammatory response to previous inadvertent subcutaneous injection(s).

Benign primary bone tumors are far more common than their malignant counterpart and are encountered in everyday practice. Imaging plays a crucial role in recognition of the nonaggressive nature of these lesions, determining the need for further imaging or follow-up. This article reviews the clinical, demographic, and radiological features of some of the more common entities classified as benign or intermediate (locally aggressive) according to the World Health Organization classification of bone tumors.

Objectives: To determine if radiological response to pre-operative radiotherapy is related to oncologic outcome in patients with extremity soft tissue sarcomas (STSs). Methods: 309 patients with extremity STS who underwent pre-operative radiation and wide resection were identified from a prospective database. Pre- and post-radiation MRI scans were retrospectively reviewed. Radiological response was defined by the modified Response Evaluation Criteria in Solid Tumours. Local recurrence-free, metastasis-free (MFS) and overall survival (OS) were compared across response groups. Results: Tumour volume decreased in 106 patients (34.3%; PR - partial responders), remained stable in 97 (31.4%; SD - stable disease), increased in 106 (34.3%; PD - progressive disease). The PD group were older (p = 0.007), had more upper extremity (p = 0.03) and high-grade tumours (p < 0.001). 81% of myxoid liposarcomas showed substantial decrease in size. There was no difference in initial tumour diameter (p = 0.5), type of surgery (p = 0.5), margin status (p = 0.4), or complications (p = 0.8) between the three groups. There were 10 (3.2%) local recurrences with no differences between the three response groups (p = 0.06). 5-year MFS was 52.1% for the PD group vs 73.8 and 78.5% for the PR and SD groups, respectively (p < 0.001). OS was similar (p < 0.001). Following multivariable analysis, worse MFS and OS were associated with higher grade, larger tumour size at diagnosis and tumour growth following pre-operative radiation. Older age was also associated with worse OS. Conclusion: STS that enlarge according to Response Evaluation Criteria in Solid Tumour criteria following pre-operative radiotherapy identify a high risk group of patients with worse systemic outcomes but equivalent local control. Advances in knowledge: Post-radiation therapy, STS enlargement may identify patients with potential for worse systemic outcomes but equivalent local control. Therefore, adjunct therapeutic approaches could be considered in these patients.

To assess the prevalence and magnetic resonance imaging appearance of metastasis presenting as a soft-tissue mass. A retrospective chart review was performed on 51 patients who presented to an orthopedic oncology center with soft-tissue masses, with a histology-proven diagnosis of soft-tissue metastasis, over a 14-year period. Their magnetic resonance imaging, primary origin, and follow-up have been assessed. Soft-tissue metastasis was identified in patients ranging from 18 to 85 years old. Most (80%) of the masses were located deep to the deep fascia. In our cohort of patients, melanoma was the most common primary malignancy contributing to soft-tissue metastasis (21.8%). Among soft-tissue metastasis from solid organs, breast and lung were the most frequent (9.1% each). Five patients had soft-tissue metastases from an unknown primary. Imaging diagnosis of soft-tissue metastases is challenging as it can demonstrate imaging appearances similar to primary soft-tissue sarcoma. The presence of a known malignancy may not be evident in everyone, and even if available, histopathology will be necessary for diagnosis if this is the only site of recurrence/metastasis to differentiate from a primary soft-tissue sarcoma. Moreover, soft-tissue metastasis may be the initial presentation of a malignancy. Primary malignancies with soft-tissue metastasis carry a poor prognosis; hence, prompt diagnosis and management in essential.

The high sensitivity and specificity of magnetic resonance imaging in diagnosis of anterior cruciate ligament (ACL) tears makes it the “gold standard” imaging modality in the diagnosis of ACL injuries. In this chapter, we discuss the imaging appearances of an intact ACL, as well as the primary and secondary imaging signs of an ACL tear. We also discuss the imaging appearances of partial ACL injuries and associated injuries identified with ACL tears.

The purpose of this study was to characterize meniscal ossicles and their association with meniscal root tears.A two-center retrospective assessment of 65 knee MRI studies with meniscal ossicles was performed. The relationship of the ossicle to the meniscal root and horn was assessed along with other findings of internal derangement of the knee.Meniscal ossicles were identified in patients ranging from 23 to 80 years old. The ossicles were located within the posterior horn and root of the medial meniscus in 57 of 65 (88%) examinations. Associated meniscal tears were seen at the site or adjacent to the ossicle in all but one examination (98%). Meniscal extrusion was present in 52% (34/65) of examinations. Associated findings included articular cartilage loss, which was severe in 51% (33/65) of examinations. Anterior cruciate ligament injury or prior anterior cruciate ligament reconstruction surgery was also identified in 58% (38/65) of examinations.Our findings show that the vast majority of meniscal ossicles are associated with posterior horn or meniscal root tears and a high incidence of focal articular cartilage loss as well as anterior cruciate ligament tears.

Background Giant cell tumour of the bone (GCTB) is an aggressive osteolytic primary tumour. GCTB is rich in osteoclast-like giant cells and contains mononuclear cells that express RANK ligand (RANKL), a key mediator of osteoclast activation. The potential therapeutic effect of denosumab was investigated with special reference to its role in joint preservation. Methods In this prospective non-randomised study patients with GCTB received denosumab for 6–11 months preoperatively. Serial radiographs and biopsy and resection tumour specimens were used to monitor response to denosumab. Results All 20 patients experienced pain relief in the first month of treatment. All patients demonstrated a positive radiographic response with improved subchondral and cortical bone which allowed intralesional tumour resection and preservation of the joint and articular surface in 18 cases. Histological examination following denosumab revealed rarely detectable osteoclast-like giant cells. There was an obvious increase in osteoid matrix and woven bone which showed rare RANK staining amongst the mononuclear cells and only focal RANKL positivity. At median 30 months follow-up after resection, local tumour recurrence occurred in three patients. Conclusion Denosumab provides favourable and consistent clinical, radiographic and pathologic responses which facilitates less aggressive surgical treatment, especially joint preservation. However, the local recurrence rate for GCTB following resection does not seem to be affected by denosumab and remains a concern.

OBJECTIVE. The purpose of this article is to review the common pitfalls in MRI of the knee and pearls on how to avoid them. CONCLUSION. MRI of the knee is highly accurate in evaluation of internal derangements of the knee. However, a variety of potential pitfalls in interpretation of abnormalities related to the knee have been identified, particularly in evaluation of the menisci, ligaments, and articular cartilage.

Epithelioid haemangioendothelioma (EHE) is a rare, welldifferentiated vascular tumour of bone, accounting for only 0.5–1% of malignant primary bone tumours [1]. Weiss and Enzinger first described it in 1982 in soft tissues [2]. EHE is the most common epithelioid vascular neoplasm of bone. EHE can present in locations other than bone, such as skin, soft tissue, liver, lungs, heart, intestine, nervous system, retroperitoneum and other body sites. However, it is most common in liver, soft tissues and bone [3]. EHE in bone typically affects adults in the second or third decade, though all age groups can be affected. Sixty percent of EHE cases occur in the long bones with tibia (23%), femur (18%) and humerus (13%) being the commonest sites [4]. Metaphysis and diaphysis are usually involved. EHE presents as synchronous or metachronous disease in 20–50% of patients [4]. Multicentric presentation has been described in 50–62%, with a predilection for bones of the lower extremities in one anatomic region [5]. Nearby or distant soft tissues and skin (Fig. 4) can be involved, and metastases to the lung have also been reported. Conventional radiography of EHE shows an expansile, lytic and often poorly demarcated lesion. A coarse trabecular or honeycombing pattern is commonly seen, with a distinctive ‘soap bubble’ matrix. A well-defined sclerotic rim is seen in most lesions [6]. Calcification is rare, and periosteal reaction is not seen unless complicated by pathologic fracture [7]. Lesions with ill-defined borders are considered more aggressive (Fig. 1). On MR imaging, the lesions are of intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Homogenous enhancement is seen after administration of gadolinium. Flow voids due to vascular channels are not typically seen on MRI of EHE, and if present, should suggest an alternative diagnosis [4]. This could be due to the small size of the vascular channels [7] (Fig. 3). Bone scintigraphy is often undertaken to identify the multicentric involvement of EHE. Increased uptake is seen at sites of involvement (Fig. 2). Doughnut-shaped lesions have been described at the site of involvement [8]. This appearance on bone scan can also be seen in benign or malignant lesions, but multiple lesions should raise the suspicion of a vascular lesion, such as haemangioendothelioma. The case presentation can be found at doi:10.1007/s00256-011-1127-1.