The incidence of skip metastases on whole bone MRI in high-grade bone sarcomas

Comparative Analysis of Skip Metastasis in Pediatric Osteosarcoma: Clinical Features and Outcomes

BACKGROUND

Skip metastasis (SM) is a synchronous regional bone metastasis. Using new imaging modalities, the detection of SM is easier and possibly more common. We reviewed patients with SM and compared their characteristics and outcomes to other patients with osteosarcoma treated at our center.

METHODS

We reviewed retrospectively children (<18 years) with newly diagnosed osteosarcoma who presented from June 2006 to March 2022. Patients' characteristics, treatment modalities, and outcomes were analyzed. All cases were discussed in a multidisciplinary clinic that included 2 experienced radiologists.

RESULTS

We identified 155 patients with osteosarcoma, among which 13 (8.3%) patients had SM detected by MRI. Patients with SM had a median age at diagnosis of 11.2 years (range 7 to 17). Three patients had lung metastasis at diagnosis. Bone scan was positive for the SM in 8 patients (62%). All patients underwent primary tumor resection after neoadjuvant chemotherapy (amputation in 5, limb salvage surgery in 8). Five had postchemotherapy necrosis ≥90% in primary tumor. Seven patients relapsed/progressed (1 local and 6 in the lung), all relapsed patients died of disease. Compared to the rest of the patients, those with SM had similar clinical features to patients without SM; outcomes were similar with no significant differences in event-free survival and overall survival ( P =0.7 and 0.3, respectively).

CONCLUSION

In this study, we observed a percentage of patients with SM comparable to previous reports. Patients with SM exhibited clinical features akin to the rest of our patients. Thorough evaluation of imaging studies and multidisciplinary care, coupled with meticulous surgical planning, are crucial for achieving a cure, which remained unjeopardized in our patients with SM.

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.

Imaging of bone marrow pitfalls with emphasis on MRI

Normal marrow contains both hematopoietic/red and fatty/yellow marrow with a predictable pattern of conversion and skeletal distribution on MRI. Many variations in normal bone marrow signal and appearances are apparent and the reporting radiologist must differentiate these from other non-neoplastic, benign or neoplastic processes. The advent of chemical shift imaging has helped in characterising and differentiating more focal heterogeneous areas of red marrow from marrow infiltration. This review aims to cover the MRI appearances of normal marrow, its evolution with age, marrow reconversion, variations of normal marrow signal, causes of oedema-like marrow signal, and some common non-neoplastic entities, which may mimic marrow neoplasms.

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.

Pediatric Osteosarcoma: Pearls and Pitfalls

Osteosarcoma is a malignant bone tumor most commonly presenting in children. It has a bimodal distribution with a peak incidence occurring during the ages of 10-14 years old and in adults greater than age 65. The first peak of osteosarcoma correlates with the increased proliferation of bone during the pubertal growth period. Osteosarcoma most frequently presents with localized bone pain, swelling, and an antalgic gait. The patient may attribute symptoms to trauma or strenuous exercise, causing the patient to be managed conservatively. In these cases, the pain persists and eventually leads to further evaluation. The most common type of osteosarcoma is the conventional high-grade osteosarcoma. For conventional osteosarcoma, the diagnosis is typically made or strongly suggested based upon the initial radiographic appearance. Other types of osteosarcomas include low grade central, telangiectatic, small-cell, surface and intracortical. Consequently, it is important for radiologists to be aware of these subtypes and the imaging features that differentiate them from other etiologies to prevent a delay in treatment.

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.

Primary extradural tumors of the spinal column: A comprehensive treatment guide for the spine surgeon based on the 5th Edition of the World Health Organization bone and soft-tissue tumor classification

BACKGROUND

In 2020, the World Health Organization (WHO) published the 5th version of the soft tissue and bone tumor classification. Based on this novel classification system, we reviewed the current knowledge on all tumor entities with spinal manifestations, their biologic behavior, and most importantly the appropriate treatment options as well as surgical approaches.

METHODS

All tumor entities were extracted from the WHO Soft-Tissue and Bone Tumor Classification (5th Edition). PubMed and Google Scholar were searched for the published cases of spinal tumor manifestations for each entity, and the following characteristics were extracted: Growth pattern, ability to metastasize, peak age, incidence, treatment, type of surgical resection indicated, recurrence rate, risk factors, 5-year survival rate, key molecular or genetic alterations, and possible associated tumor syndromes. Surgical treatment strategies as well as nonsurgical treatment recommendations are presented based on the biologic behavior of each lesion.

RESULTS

Out of 163 primary tumor entities of bone and soft tissue, 92 lesions have been reported along the spinal axis. Of these 92 entities, 54 have the potential to metastasize. The peak age ranges from conatal lesions to 72 years. For each tumor entity, we present recommended surgical treatment strategies based on the ability to locally destruct tissue, to grow, recur after resection, undergo malignant transformation as well as survival rates. In addition, potential systemic treatment recommendations for each tumor entity are outlined.

CONCLUSION

Based on the 5th Edition of the WHO bone and soft tumor classification, we identified 92 out of 163 tumor entities, which potentially can have spinal manifestations. Exact preoperative tissue diagnosis and interdisciplinary case discussions are crucial. Surgical resection is indicated in a significant subset of patients and has to be tailored to the specific biologic behavior of the targeted tumor entity based on the considerations outlined in detail in this article.

Malignant fibrous histiocytoma of the bone in a traumatic amputation stump: A case report and review of the literature

BACKGROUND

Malignant fibrous histiocytoma (MFH) is one of the most common soft tissue sarcomas among adults. It is characterized by large size, high grade, and biological aggressiveness. There are many reports of MFH after local stimulation, such as bone fracture, implants, and chronic osteomyelitis. In this paper, we report a patient who developed MFH 6 years after amputation, suggesting that wound healing and mechanical force play a role in the local stimulation of this disease.

CASE SUMMARY

A 66-year-old man complained of persistent pain in his residual mid-thigh. He had undergone amputation surgery due to a traffic accident 6 years prior. Physical examination showed tenderness but no abnormalities in appearance. X-ray radiographs and magnetic resonance imaging supported the diagnosis of a tumor, and a biopsy confirmed that the lesion was MFH. The patient received neoadjuvant chemotherapy and left hip disarticulation. During the 6-mo follow-up, there were no symptoms of recurrence.

CONCLUSION

Postsurgery MFH has been reported before, and many studies have attributed it to the biological effects of implants. Our case report shows that this disease can develop without an implant and thus highlights the importance of local stimulation. The wound-healing process and mechanical force can both promote this tumor, but whether they directly cause MFH needs further investigation.

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.

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.

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.