Adverse impact of regional lymph node involvement in osteosarcoma

Single-cell and spatial transcriptomics reveal metastasis mechanism and microenvironment remodeling of lymph node in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignant bone tumor and is highly prone to metastasis. OS can metastasize to the lymph node (LN) through the lymphatics, and the metastasis of tumor cells reestablishes the immune landscape of the LN, which is conducive to the growth of tumor cells. However, the mechanism of LN metastasis of osteosarcoma and remodeling of the metastatic lymph node (MLN) microenvironment is not clear.

METHODS

Single-cell RNA sequencing of 18 samples from paracancerous, primary tumor, and lymph nodes was performed. Then, new signaling axes closely related to metastasis were identified using bioinformatics, in vitro experiments, and immunohistochemistry. The mechanism of remodeling of the LN microenvironment in tumor cells was investigated by integrating single-cell and spatial transcriptomics.

RESULTS

From 18 single-cell sequencing samples, we obtained 117,964 cells. The pseudotime analysis revealed that osteoblast(OB) cells may follow a differentiation path from paracancerous tissue (PC) → primary tumor (PT) → MLN or from PC → PT, during the process of LN metastasis. Next, in combination of bioinformatics, in vitro and in vivo experiments, and immunohistochemistry, we determined that ETS2/IBSP, a new signal axis, might promote LN metastasis. Finally, single-cell and spatial dissection uncovered that OS cells could reshape the microenvironment of LN by interacting with various cell components, such as myeloid, cancer-associated fibroblasts (CAFs), and NK/T cells.

CONCLUSIONS

Collectively, our research revealed a new molecular mechanism of LN metastasis and clarified how OS cells influenced the LN microenvironment, which might provide new insight for blocking LN metastasis.

Metastatic lymph node targeted CTLA4 blockade: a potent intervention for local and distant metastases with minimal ICI-induced pneumonia

BACKGROUND

Immune checkpoint blockade (ICB) elicits a strong and durable therapeutic response, but its application is limited by disparate responses and its associated immune-related adverse events (irAEs). Previously, in a murine model of lymph node (LN) metastasis, we showed that intranodal administration of chemotherapeutic agents using a lymphatic drug delivery system (LDDS) elicits stronger therapeutic responses in comparison to systemic drug delivery approaches, while minimizing systemic toxicity, due to its improved pharmacokinetic profile at the intended site. Importantly, the LN is a reservoir of immunotherapeutic targets. We therefore hypothesized that metastatic LN-targeted ICB can amplify anti-tumor response and uncouple it from ICB-induced irAEs.

METHODS

To test our hypothesis, models of LN and distant metastases were established with luciferase expressing LM8 cells in MXH10/Mo-lpr/lpr mice, a recombinant inbred strain of mice capable of recapitulating ICB-induced interstitial pneumonia. This model was used to interrogate ICB-associated therapeutic response and immune related adverse events (irAEs) by in vivo imaging, high-frequency ultrasound imaging and histopathology. qPCR and flowcytometry were utilized to uncover the mediators of anti-tumor immunity.

RESULTS

Tumor-bearing LN (tbLN)-directed CTLA4 blockade generated robust anti-tumor response against local and systemic metastases, thereby improving survival. The anti-tumor effects were accompanied by an upregulation of effector CD8T cells in the tumor-microenvironment and periphery. In comparison, non-specific CTLA4 blockade was found to elicit weaker anti-tumor effect and exacerbated ICI-induced irAEs, especially interstitial pneumonia. Together these data highlight the importance of tbLN-targeted checkpoint blockade for efficacious response.

CONCLUSIONS

Intranodal delivery of immune checkpoint inhibitors to metastatic LN can potentiate therapeutic response while minimizing irAEs stemming from systemic lowering of immune activation threshold.

Machine Learning-Based Prediction of Lymph Node Metastasis Among Osteosarcoma Patients

Background

Regional lymph node metastasis is a contributor for poor prognosis in osteosarcoma. However, studies on risk factors for predicting regional lymph node metastasis in osteosarcoma are scarce. This study aimed to develop and validate a model based on machine learning (ML) algorithms.

Methods

A total of 1201 patients, with 1094 cases from the surveillance epidemiology and end results (SEER) (the training set) and 107 cases (the external validation set) admitted from four medical centers in China, was included in this study. Independent risk factors for the risk of lymph node metastasis were screened by the multifactorial logistic regression models. Six ML algorithms, including the logistic regression (LR), the gradient boosting machine (GBM), the extreme gradient boosting (XGBoost), the random forest (RF), the decision tree (DT), and the multilayer perceptron (MLP), were used to evaluate the risk of lymph node metastasis. The prediction model was developed based on the bestpredictive performance of ML algorithm and the performance of the model was evaluatedby the area under curve (AUC), prediction accuracy, sensitivity and specificity. A homemade online calculator was capable of estimating the probability of lymph node metastasis in individuals.

Results

Of all included patients, 9.41% (113/1201) patients developed regional lymph node metastasis. ML prediction models were developed based on nine variables: age, tumor (T) stage, metastasis (M) stage, laterality, surgery, radiation, chemotherapy, bone metastases, and lung metastases. In multivariate logistic regression analysis, T and M stage, surgery, and chemotherapy were significantly associated with lymph node metastasis. In the six ML algorithms, XGB had the highest AUC (0.882) and was utilized to develop as prediction model. A homemade online calculator was capable of estimating the probability of CLNM in individuals.

Conclusions

T and M stage, surgery and Chemotherapy are independent risk factors for predicting lymph node metastasis among osteosarcoma patients. XGB algorithm has the best predictive performance, and the online risk calculator can help clinicians to identify the risk probability of lymph node metastasis among osteosarcoma patients.

The Construction and Development of a Clinical Prediction Model to Assess Lymph Node Metastases in Osteosarcoma

Background: This study aimed to construct a clinical prediction model for osteosarcoma patients to evaluate the influence factors for the occurrence of lymph node metastasis (LNM).

Methods: In our retrospective study, a total of 1,256 patients diagnosed with chondrosarcoma were enrolled from the SEER (Surveillance, Epidemiology, and End Results) database (training cohort, n = 1,144) and multicenter dataset (validation cohort, n = 112). Both the univariate and multivariable logistic regression analysis were performed to identify the potential risk factors of LNM in osteosarcoma patients. According to the results of multivariable logistic regression analysis, A nomogram were established and the predictive ability was assessed by calibration plots, receiver operating characteristics (ROCs) curve, and decision curve analysis (DCA). Moreover, Kaplan-Meier plot of overall survival (OS) was plot and a web calculator visualized the nomogram.

Results: Five independent risk factors [chemotherapy, surgery, lung metastases, lymphatic metastases (M-stage) and tumor size (T-stage)] were identified by multivariable logistic regression analysis. What's more, calibration plots displayed great power both in training and validation group. DCA presented great clinical utility. ROCs curve provided the predictive ability in the training cohort (AUC = 0.805) and the validation cohort (AUC = 0.808). Moreover, patients in LNN group had significantly better survival than that in LNP group both in training and validation group.

Conclusion: In this study, we constructed and developed a nomogram with risk factors, which performed well in predicting risk factors of LNM in osteosarcoma patients. It may give a guide for surgeons and oncologists to optimize individual treatment and make a better clinical decision.

Number of metastases and their response to chemotherapy impact survival of patients with isolated lung metastases from bone-derived sarcoma

Background

Pulmonary metastasectomy (PM) is an established treatment for selected patients with metastatic sarcomas. The aim of this study was to examine our institutional experience and evaluate factors predicting outcome.

Methods

We retrospectively reviewed all patients undergoing PM for bone sarcoma in our center from 2001 to 2019. Survival was calculated from the date of PM. Impact on survival of clinical parameters was assessed.

Results

Thirty-eight patients (27 males, 71%) were included. Histology was osteosarcoma (n = 20, 53%), Ewing sarcoma (n = 13, 34%) and chondrosarcoma (n = 5, 13%). Twelve patients (31.5%) had synchronous metastases, all received chemotherapy before PM. Median number of metastases was 3 (1 to 29). Twenty (53%) patients had mediastinal lymph node sampling. One patient had positive lymph nodes. Ninety-day mortality was 0%. Three and 5-year PFS were 24.5 and 21%, respectively. Three and 5-year OS were 64.5 and 38.5%, respectively. More than three metastases and progression under chemotherapy were significant independent predictors for OS.

Conclusion

PM is a safe procedure and encouraging long-term outcome can be achieved. Patients with progression of pulmonary metastases under chemotherapy as well as patients with more than three metastases had significantly worse OS.

Surgical resection of the primary lesion for osteosarcoma patients with metastasis at initial diagnosis

BACKGROUND

Approximately 10-20% of osteosarcoma patients present with metastasis on diagnosis. Completely resecting the lesion is associated with better prognosis. However, evidence regarding optimal surgical strategies for patients with unresectable metastasis is limited.

METHODS

This retrospective analysis was based on the Japanese Nationwide Bone and Soft Tissue Tumor registry. In total, 335 patients diagnosed with osteosarcoma with metastasis were included. Factors affecting overall survival were identified using multivariate analysis. Kaplan-Meier method was used to compare the overall survival by the status of surgical intervention. Two hundred and four patients who did not undergo surgery for metastasis were divided into two groups, depending on whether they underwent surgery for the primary lesion. The background differences between these two groups were adjusted with propensity score matching, with 43 patients per group. The overall survival was calculated using the Kaplan-Meier method and compared with a log-rank test.

RESULTS

Factors positively impacting overall survival were age <40, female sex, extremity origin, surgery for the primary lesions, surgery for metastasis and radiotherapy without surgery. For patients with unresectable metastasis, after propensity score matching, the survival rate was higher in the group that underwent primary lesion surgery than the group without surgery. Their median survival was 19 (95% confidence interval: 11.7-26.3) and 11 months (95% confidence interval: 4.5-17.5) (P = 0.02), respectively.

CONCLUSIONS

Surgical resection of the primary osteosarcoma lesion did not worsen prognosis, even in patients with unresectable metastasis. Further study is needed to identify which patient group will benefit from primary lesion resection.

Risk factors of regional lymph node (RLN) metastasis among patients with bone sarcoma and survival of patients with RLN-positive bone sarcoma

Background

Regional lymph node metastasis (RLNM) has been reported to be a prognostic factor for poor survival outcomes of bone sarcoma. However, studies about risk factors for RLNM of bone sarcoma are extremely rare, and the outcome of such patients remains to be explored. We aimed to identify risk factors for RLNM of bone sarcoma and conduct survival analysis for patients with bone sarcoma with RLNM.

Methods

A total of 10,641 patients confirmed of malignant bone sarcomas from 1983 to 2014 were identified from the Surveillance, Epidemiology, and End Results (SEER) database, with 311 being regional lymph node positive. Logistic regression analysis was used to identify risk factors for RLNM, while the Cox proportional hazards model and the Fine and Gray’s regression model were used for survival analysis.

Results

The proportion of RLNM was 6.0% in Ewing sarcoma, 2.5% in osteosarcoma and 1.1% in chondrosarcoma. Other bone tumors together had a RLNM rate of 4.2%. Risk factors identified by the logistic regression analysis for RLNM were male patients, primary tumor site, tumor type and size. The multivariate Cox regression analysis suggested age, race, distant metastasis, tumor type and surgical treatment to be prognostic factors for the overall survival of patients with RLNM. Taking non-cancer-specific death as a competing risk, however, we found only age between 30–60 years [sub-distribution hazard ratio (SHR), 1.528, 95% CI, 1.028–2.271; P=0.02], distant metastasis (SHR, 2.418, 95% CI, 1.682–3.474; P<0.001) and surgery treatment (SHR, 0.493, 95% CI, 0.339–0.718; P<0.001) remained significant for the cancer-specific survival in the Fine and Gray’s regression model.

Conclusions

Predictive factors for RLNM of bone sarcoma are sex, tumor site, type and size. In the presence of RKNM, only age, distant metastasis and surgery treatment are prognostic factors for the outcome of patients with bone sarcoma.

Popliteal lymph nodes in patients with osteosarcoma: are they metastatic?

PURPOSE

To evaluate the prevalence, imaging appearance, and significance of popliteal lymph nodes (PLN) on magnetic resonance imaging (MRI) in patients with distal femoral or proximal tibial osteosarcoma (OS).

METHOD AND MATERIALS

This study included consecutive patients with OS presenting from May 2016 to March 2018. Inclusion criteria were patients with distal femoral or proximal tibial OS with MRI and pathology at our institution. On MRI, two radiologists recorded primary tumor features (size, location, signal, extra-compartmental extension), and PLN characteristics (mean size, presence/absence of fatty hilum, mineralization, PET/bone scintigraphy avidity, contrast enhancement, and diffusion restriction). Tumor histology, stage, and clinical follow-up were recorded. Descriptive statistics were provided.

RESULTS

Sixteen patients with OS (age 20 ± 10 (range10-40) years, 10/16 male) were included. Although 81% (13/16) of the patients had PLNs at presentation (size range 0.3-3.6 cm), fewer patients had extra-compartmental spread: intra-articular extension 50% (8/16), skip lesions 19% (3/16), lung metastases 31% (5/16), and osseous metastases 12% (2/16). Four (25% (4/16)) patients had PLN ≥ 1 cm; two were histologically proven reactive. One was presumed metastatic due to rapid development, mineralization, and FDG-avidity on PET/CT. The other ≥ 1 cm PLNs along with all twelve (75% (12/16)) that were < 1 cm in mean diameter were presumed non-metastatic with documented stability for at least 12 months of follow-up.

CONCLUSION

PLNs are frequently visible on MRI in patients with OS but are rarely (prevalence = 6%) metastatic. Features on MRI which may suggest metastatic PLNs include large size > 1 cm and loss of a fatty hilum.

Composite sarcoma of bone with focal rhabdomyosarcoma and lymph node metastasis in an adolescent

Composite sarcoma of bone is a very rare entity that primarily affects adolescent and young adult patients. It usually combines areas of liposarcoma and osteosarcoma, and up to 60% of cases have metastatic disease at diagnosis. It is a highly aggressive pathology with intrinsic resistance to bone sarcoma conventional treatments. The prognosis is poor, with long-term survival rates not exceeding 30%. We present the case of an adolescent female diagnosed with an aggressive composite sarcoma of bone with rhabdomyosarcoma foci and loco-regional lymph node involvement.

Cystic extraskeletal osteosarcoma: Three case reports and review of the literature

Extraskeletal osteosarcoma is a rare soft tissue sarcoma and typically appears as a solid mass with variable mineralization. A few cases of extraskeletal osteosarcoma have shown extensive hemorrhagic changes or bleeding due to its high-grade malignancy; however, to the best of our knowledge, no previous reports have described the pathological characteristics of tumors with non-hemorrhagic cystic change. The present report discusses three cases involving cystic lesions with a solid area at the periphery that arose in soft tissues. The large cystic spaces contained only yellowish-brown fluid and little or no blood, with no clear pathological necrotic tissue. The solid component comprised a focal area of osteoid production by highly anaplastic sarcomatous cells. All of the cases showed high-grade malignancy histologically, and the average maximum diameter was approximately 175 mm. The tumors were located at the adductor muscles in two cases and at the intermuscular region of the hamstring muscles in one case. All of the patients consulted a doctor after more than half a year had passed since the recognition of swelling or a mass on their affected extremities. Surgical treatment was performed for all patients. One patient had lymph node metastasis, and another had lymphoedema after surgery, but no histological invasion to the lymphatic ducts was observed in the excised specimen. Degenerative changes in the fluid content over a long time-course as a result of tumor bleeding or necrosis, rather than lymphorrhea by lymphatic channel invasion of the tumor, might have contributed to the formation of the cystic lesion. Only 1 patient who underwent chemotherapy remained clinically disease-free over 10 years after surgery. Chemotherapy regimens for osteosarcoma rather than those for soft tissue sarcoma are mostly effective for extraskeletal osteosarcoma, so the diagnosis by a biopsy is essential. It is important to consider extraskeletal osteosarcoma in the differential diagnosis of soft tissue tumor with cystic form and calcification and a long clinical course before consulting a doctor.

Regional Lymph Node Involvement Is Associated With Poorer Survivorship in Patients With Chondrosarcoma: A SEER Analysis

BACKGROUND

Regional lymph node involvement is thought to be rare in patients with chondrosarcoma, but its actual prevalence is unclear. Additionally, it is often not considered when prognostic factors are analyzed in patients with chondrosarcoma. However, it has been well established that lymph node involvement is a poor prognostic marker in patients with many types of bone and soft tissue sarcoma, including rhabdomyosarcoma, osteosarcoma, and Ewing's sarcoma. Although lymph node metastases are rare among all sarcoma types, it is important to consider whether lymph node metastases should be assessed in patients with chondrosarcoma because these metastases may impact survival.

QUESTIONS/PURPOSES

(1) What is the reported prevalence of regional lymph node involvement in patients with chondrosarcoma? (2) Do patients who have chondrosarcomas with regional lymph node involvement have different clinicopathologic presentations and survival than patients without regional lymph node involvement? (3) Is regional lymph node involvement independently associated with prognosis in patients with chondrosarcoma?

METHODS

The data of patients with chondrosarcoma registered in the Surveillance Epidemiology and End Results database (SEER) (1988-2015) were analyzed for the reported prevalence of regional lymph node involvement and its relationship with clinicopathologic features and the 5-year overall survival rate. From 1988 to 2015, 5528 patients with chondrosarcoma were registered in the SEER database. After screening by the inclusion criterion-chondrosarcoma as the first primary tumor, diagnosis with histology confirmation, patients with active followup and available information about regional node status-3374 patients met the inclusion criteria and were analyzed. Demographics and clinicopathologic data were compared using chi-square or Fisher's exact tests. Logistic regression analysis was used to assess the adjusted odds ratio. The overall survival rate was estimated with Kaplan-Meier curves and log-rank tests. Univariate and multivariate analyses of overall survival were performed with Cox proportional hazard models. In addition, a series of sensitivity analyses were performed to assess the robustness of the final Cox proportional hazard model.

RESULTS

Forty-four patients (1.3%) were recorded in the database as having regional lymph node involvement at the time of the primary diagnosis. Lymph node metastases were more likely to be reported in an extraskeletal primary site (3% [13 of 426] versus 1% [31 of 2948], adjusted odds ratio [OR] = 2.9, 95% CI, 1.5-5.8; p = 0.003) for bone primary sites and tumors with maximum diameter ≥ 8 cm (2% [26 of 1045] versus 1% [10 of 1075], adjusted OR = 2.9, 95% CI, 1.3-6.3; p = 0.008) and poorer differentiation (4% [24 of 608] versus 1% [14 of 2308], adjusted OR = 4.0, 95% CI, 2.0-8.2; p < 0.001), and in those with distant metastases (7% [14 of 203] versus 1% [30 of 3148], adjusted OR = 3.5, 95% CI, 1.7-7.1, p = 0.001). The 5-year overall survival rates of patients with and without regional lymph node involvement were 28% (95% CI, 15-42%) and 77% (95% CI, 75-78%), respectively (p < 0.001). After controlling for age, sex, race, grade, metastatic status, size, and histologic subtype, the presence of regional lymph node involvement was associated with poorer survival (hazard ratio, 2.20; 95% CI, 1.50-3.24; p < 0.001); this finding was confirmed in several sensitivity analyses.

CONCLUSION

The prevalence of regional lymph node involvement in patients with chondrosarcoma was 1.3% in the SEER database. Although chondrosarcomas are rare, patients with chondrosarcomas who have regional node metastases have a poorer prognosis than those who have not reported to have them. This may underrepresent the true proportion of patients with lymph node metastases given the inaccuracies of reporting in this database, but we believe these findings indicate that clinicians should examine patients more carefully for chondrosarcoma with lymph node metastases. Future studies are needed to assess potential treatment strategies to improve the prognosis of these patients.

LEVEL OF EVIDENCE

Level III, prognostic study.

Development and Validation of Nomograms Predicting Overall and Cancer-Specific Survival of Spinal Chondrosarcoma Patients

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To develop and validate nomograms to predict overall survival (OS) and cancer-specific survival (CSS) of spinal chondrosarcoma patients.

SUMMARY OF BACKGROUND DATA

In this era of personalized medicine, data those are available to predict the survival of spinal chondrosarcoma patients are still limited due to the rarity of the disease. Nomogram, which has been widely used in clinical oncology, could conveniently and precisely predict survival outcome for individual patient.

METHODS

We retrospectively collected 450 spinal chondrosarcoma patients from the Surveillance, Epidemiology, and End Results (SEER) database between 1984 and 2013. Univariate log-rank and multivariate Cox analyses were used to identify independent prognostic factors. These prognostic factors were included in the nomograms, which predict 3- and 5-year OS and CSS rate. The nomograms were bootstrap validated internally and externally.

RESULTS

A total of 450 patients were collected and randomly assigned into the training (n = 225) and validation (n = 225) cohorts. Age, histologic subtype, grade, tumor size, stage, and surgery were identified as independent prognostic factors for OS and CSS (all P < 0.05) and were further incorporated to construct the nomograms. The concordance indices (C-indices) for internal validation of OS and CSS prediction were 0.807 and 0.821, while for external validation of OS and CSS prediction were 0.756 and 0.767. Internal and external calibration plots both revealed an excellent agreement between nomogram prediction and actual survival.

CONCLUSION

Nomograms were developed to predict OS and CSS for spinal chondrosarcoma patients. The nomograms could assist clinicians in making more accurate survival evaluation and identifying patients with high risk of mortality.

LEVEL OF EVIDENCE

4.

Prognostic nomograms for predicting overall and cancer-specific survival of high-grade osteosarcoma patients

Aim

The present study aimed to develop nomograms estimating survival for patients with high-grade osteosarcoma.

Methods

1990 patients with high-grade osteosarcoma between 1994 and 2013 were retrospectively retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Data from 12 cancer registries (n = 1460) were used to conduct multivariate Cox analysis to identify independent prognostic factors. Nomograms which estimate 3- and 5-year overall survival (OS) and cancer-specific survival (CSS) were constructed. The nomograms were internally validated for calibration and were also externally validated with an independent patient cohort from 1 cancer registry (n = 530).

Results

Age, primary site, tumor size, use of surgery, and extent of disease were found to be independently associated with OS and CSS (p < 0.05). The nomograms estimating 3- and 5-year OS and CSS were developed based on these prognostic factors. The concordance indices were high in internal validation (0.726 for OS and 0.731 for CSS) and external validation (0.716 for OS and 0.724 for CSS). Internal and external calibration plots demonstrated a good agreement between nomogram prediction and actual observation.

Conclusions

We constructed nomograms that accurately predict OS and CSS of high-grade osteosarcoma patients. The nomograms can be used for counseling patients and establishing risk stratification.

Risk factors for metastasis at presentation with conventional chondrosarcoma: a population-based study

PURPOSE

The aim of the study was to investigate risk factors for metastasis at diagnosis.

METHODS

We collected patients diagnosed with conventional chondrosarcoma between 1983 and 2014 from the Surveillance, Epidemiology, and End Results (SEER) database. Each patient was classified as having metastatic or localized disease. Univariate and multivariate logistic regression analyses were applied to determine which characteristics were risk factors for metastasis at diagnosis.

RESULTS

Two thousand three hundred forty-nine patients were collected and 180 patients had metastasis at presentation. Data on age, gender, primary site, grade, and tumour size were enrolled into the multivariate logistic analysis. Greater age (60 years or older: OR = 1.872, 95% CI, 1.206 to 2.904), axial or craniofacial location (spine: OR = 1.775, 95% CI, 1.188 to 2.651; thoracic cage: OR = 2.034, 95% CI, 1.321 to 3.134; craniofacial bones: OR = 5.507, 95% CI, 3.001 to 10.107), higher grade (grade II: OR = 1.849, 95%CI, 1.181 to 2.895; grade III: OR = 4.016, 95%CI, 2.513 to 6.418), and larger tumour size (size over 10 cm: OR = 7.135, 95%CI, 2.130 to 23.893) were associated with an increased risk of metastasis at presentation.

CONCLUSIONS

Conventional chondrosarcoma patients with greater age, axial or craniofacial tumour location, higher grade, and larger tumor size were more likely to have metastasis at diagnosis.

[Lymph node metastasis of osteosarcomas]

Lymph node metastasis of osteosarcomas is a rather rare phenomenon; according to different authors, the incidence of lymph node metastasis is 4 to 11%. The detection of lymph node metastases in osteosarcoma is associated with a significant reduction in the 5-year survival of patients and allows its classification as clinical stage IV tumor. The risk factors for lymph node metastases in patients with bone sarcomas are age (≥64 years), gender (female), nosological entity (undifferentiated pleomorphic sarcoma, osteosarcoma, chondrosarcoma), tumor depth (muscle, bone), and the size of primary tumor (>5 сm). The mechanism of lymph node metastasis of osteosarcomas seems to be related to mesenchymal-to-epithelial transition.

Popliteal lymph node metastasis of tibial osteoblastic osteosarcoma

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Lymph node metastasis of osteosarcoma, which is a rare entity.

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Metastatic patterns could not be clearly explained.

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The effects of lymph node metastasis on prognosis are also not clearly defined and further studies are needed.

INTRODUCTION

We report a case with lymph node metastasis of osteosarcoma, which is a rare entity in comparison to hematogeneous lung or bone metastasis.

PRESENTATION OF CASE

Twenty-seven years old male patient referred to our clinic complaining of ongoing left knee pain and swelling since one month without a history of prior trauma. Magnetic resonance imaging (MRI) revealed a mass of malignant nature which causes more prominent expansion and destruction of the bone distally with periosteal reaction. A lymphadenomegaly 16 mm × 13 mm in diameter was also present in the popliteal fossa having the same signal pattern with the primary lesion. Thirteen weeks following the first referral of the patient, wide resection and reconstruction with modular tumor prosthesis was performed. Popliteal lymph node was excised through the same incision. Pathologic examination of the resected speciman reported osteoblastic osteosarcoma. The lymph node extirpated from the popliteal fossa was reported to be a metastasis of the primary tumor.

DISCUSSION

Osteosarcoma of the long bones is the most common primary malignant bone neoplasm of both childhood and adulthood. Osteosarcomas commonly metastasize hematogeneously to the lungs and bones. Lymph node metastasis is a rare entity. Similar studies report rates between 2.3% and 4%. It is not clearly explained, how lymph node metastasis in osteosarcoma occurs despite lack of lymphatic drainage in normal cortical and spongious bone.

CONCLUSION

Lymph node metastasis of osteosarcoma is a rare entity and metastatic patterns could not be clearly explained. On the other hand, the effects of lymph node metastasis on prognosis are also not clearly defined and further studies are needed.

Clinical Features and Outcomes Differ between Skeletal and Extraskeletal Osteosarcoma

Background. Extraskeletal osteosarcoma (ESOS) is a rare subtype of osteosarcoma. We investigated patient characteristics, overall survival, and prognostic factors in ESOS. Methods. We identified cases of high-grade osteosarcoma with known tissue of origin in the Surveillance, Epidemiology, and End Results database from 1973 to 2009. Demographics were compared using univariate tests. Overall survival was compared with log-rank tests and multivariate analysis using Cox proportional hazards methods. Results. 256/4,173 (6%) patients with high-grade osteosarcoma had ESOS. Patients with ESOS were older, were more likely to have an axial tumor and regional lymph node involvement, and were female. Multivariate analysis showed ESOS to be favorable after controlling for stage, age, tumor site, gender, and year of diagnosis [hazard ratio 0.75 (95% CI 0.62 to 0.90); p = 0.002]. There was an interaction between age and tissue of origin such that older patients with ESOS had superior outcomes compared to older patients with skeletal osteosarcoma. Adverse prognostic factors in ESOS included metastatic disease, larger tumor size, older age, and axial tumor site. Conclusion. Patients with ESOS have distinct clinical features but similar prognostic factors compared to skeletal osteosarcoma. Older patients with ESOS have superior outcomes compared to older patients with skeletal osteosarcoma.