Introduction
Since the publication of multiple randomized controlled trials in 2015,1-5) endovascular thrombectomy (EVT) for acute ischemic stroke due to large vessel occlusion has been widely accepted as the standard therapy. However, optimal treatment of acute ischemic stroke in patients with cancer remains controversial. It is well-known that patients with cancer are more likely to develop strokes.6-9) Previous reports have shown that cancer-associated stroke accounts for 6%-7% of mechanical thrombectomy cases.10-12) Potential mechanisms by which cancer contributes to stroke include tumor-induced hypercoagulability (such as nonbacterial thrombotic endocarditis and Trousseau's syndrome), tumor emboli, direct invasion or compression of arteries, infection, and secondary effects of cancer therapy.13) Although the reported incidence of metastatic cardiac tumors is not uncommon, reaching as high as 18.3%,14) cerebral infarction and vessel occlusion due to tumor emboli from cardiac metastasis have been rarely reported.15,16) In the present case of metastatic chondrosarcoma, histopathological examination showed that mechanical thrombectomy retrieved tumor cells migrating from cardiac metastasis.
Case presentation
Written informed consent was obtained from the patient for the presentation of this case report. A 53-year-old woman with chondrosarcoma was admitted to our emergency room with sudden onset of right hemiparesis and motor aphasia. She had been diagnosed with extraskeletal chondrosarcoma in the left femur 5 years before with metastases to the left femoral lymph nodes and thoracic spine 2 years earlier. Additionally, lung metastasis had been identified 3 months before admission to our hospital.
On arrival, her blood pressure was 99/73 mmHg, and her pulse was regular. Auscultation revealed decreased breath sounds and a murmur. Neurological examination showed disturbed consciousness, aphasia, and right hemiplegia. Her Glasgow Coma Scale score was 9, and her National Institutes of Health (NIH) Stroke Scale score was 27.
Chest X-ray on admission revealed metastatic tumors in both lungs and massive pleural effusion in the left lung (Supplementary Figure 1A), with marked displacement of the trachea due to the metastatic lung tumor. Laboratory data showed an elevated white blood cell count of 12.5 × 103/μL (reference range: 3.9-9.8 × 103/μL), elevated serum C-reactive protein at 2.89 mg/dL (reference range: 0.00-0.14), and an elevated D-dimer level of 7.1 μg/mL (reference range: <1.0). Her NT-proBNP concentration was 37.6 pg/mL (reference range: 0-125).
A head computed tomography (CT) scan, performed because of suspicion of acute ischemic stroke, revealed a small hemorrhage in the left corona radiata (Fig. 1A). Subsequent perfusion CT imaging showed occlusion of the left internal carotid artery and a large area of salvageable tissue in the territory of the left middle cerebral artery (Fig. 1B and C). Intravenous thrombolytic therapy was contraindicated because of the intracranial hemorrhage; therefore, direct EVT using the continuous aspiration prior to intracranial vascular embolectomy technique17) was conducted to salvage the hypoxic brain tissue.
A 9-Fr Optimo balloon-guiding catheter (Tokai Medical Products, Kasukabe, Japan) was placed in the left internal carotid artery via a femoral approach. Preoperative angiography confirmed occlusion of the left internal carotid artery (Fig. 2A). A React 71 catheter (Medtronic, Minneapolis, MN, USA) was used as the aspiration catheter, and an EmboTrap III device (5.0 × 37 mm; Cerenovus, Irvine, CA, USA) was deployed via the C2 segment of the left internal carotid artery toward the M1 segment of the middle cerebral artery. Immediate flow restoration was achieved following stent deployment.
The distal aspiration catheter, through which continuous local aspiration was performed, was advanced over the stent retriever until the drip slowed. Both were then removed as a single unit into the cervical guiding catheter. As a result, a white cell mass was retrieved, stuck in the aspiration catheter (Fig. 3A), and postoperative carotid angiography showed complete revascularization (Fig. 2B).
After the procedure, the patient regained the ability for basic verbal communication but remained hemiplegic, with a NIH Stroke Scale score of 19. Head magnetic resonance imaging/angiography performed the following day showed cerebral infarction in the territory of the left middle cerebral artery, with maintained patency of the left internal carotid and middle cerebral arteries.
Pathological analysis of the retrieved emboli revealed atypical cuboidal cells proliferating in a small, glandular cavity-like pattern (Fig. 3B). Immunostaining was positive for CK AE1/AE3 and S100 (Fig. 3C) and negative for CK7, CK20, TTF-1, and Napsin A. These findings were consistent with the embolic origin from the preexisting chondrosarcoma. A prior non-contrast chest CT had shown multiple pulmonary metastases and mediastinal lymph node metastases in the left pulmonary hilum, with invasion of the pulmonary vein (Supplementary Figure 1B). Transthoracic echocardiography revealed a mobile, protruding mass in the left atrium (Supplementary Figure 1C). Based on these findings, the tumor embolism was diagnosed as originating from cardiac metastasis of chondrosarcoma.
Despite slight neurological recovery, the patient died of respiratory failure on the 15th day after onset.
Discussion
Here, we describe a patient with cardiac metastasis of chondrosarcoma who developed an embolic stroke. Histological examination of the cells retrieved during endovascular treatment revealed that the cerebral vessel was occluded by tumor cells.
Chondrosarcomas are a diverse group of malignant bone tumors originating from cartilaginous matrix-producing cells.18) They typically affect adults, with common sites including the pelvis, femur, and shoulder girdle. These tumors range from relatively benign to highly malignant, aggressive high-grade forms. Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant subtype, with a reported prevalence of 1 in 1,000,000. Despite its classification as a chondrosarcoma, EMC typically arises outside the skeletal system.19) It is characterized by a distinct microscopic appearance, with an abundant myxoid matrix and tumor cells arranged in a cord-like or lobular pattern. A notable feature of EMC is its slow-growing nature and relatively indolent clinical course compared with other sarcomas. However, it tends to recur locally and metastasize-particularly to the lungs-even several years after the initial diagnosis.
While the lungs are the most frequent site of chondrosarcoma metastases due to tumor cells traveling through the bloodstream to establish secondary growths, other locations such as lymph nodes and visceral organs can occasionally be affected. Several cases of tumor embolism resulting from cardiac metastasis of chondrosarcoma have been reported in the literature.20)
Stroke and cancer are both common causes of morbidity and mortality in the aging population. The coexistence of cancer and stroke is often observed as cancer survival improves, and performing EVT for ischemic stroke in patients with active cancer is not uncommon.21) Notably, patients with stage 4 cancers have been reported to have more than a six-fold increased risk of ischemic stroke within the first year following diagnosis.7) Most patients with both stroke and cancer show evidence of metastasis.13) Potential mechanisms contributing to the increased risk of stroke have been thoroughly reviewed.22,23) Major causes include atherosclerosis, intravascular coagulopathy, nonbacterial thrombotic endocarditis, and sepsis.6) In contrast, the reported incidence of cardiac metastasis is higher than previously expected.14,24) Table 1 summarizes cases of patients with tumor embolism due to cardiac metastasis who were treated endovascularly.25-34) The pathophysiological mechanisms of cardiac metastasis have been thoroughly reviewed in previous literature. Bussani suggested that tumors can spread to the heart through 4 alternative paths: 1) by direct extension, 2) through the bloodstream, 3) through the lymphatic system, and 4) by intracavitary diffusion through either the inferior vena cava or the pulmonary veins.14) About two-thirds of all cardiac metastases involved the pericardium (69.4%), one-third the epicardium (34.2%) or the myocardium (31.8%) and only 5% the endocardium. In our review, the fourth mechanism may be applicable in our case. Despite their rarity, cardioembolic strokes associated with metastatic cardiac tumors may be underdiagnosed. One possible explanation is that histological confirmation was not feasible in the pre-EVT era, except through autopsy.35) Other explanations are that patients with cardiac metastasis are mostly clinically silent except for those with a large amount of pericardial effusion, and that patients with active cancer often do not undergo detailed evaluation or EVT36) because of their poor prognosis-even though current American Heart Association/American Stroke Association guidelines do not consider active cancer an absolute contraindication for intravenous thrombolysis or EVT in acute ischemic stroke.37)
Table 1
Summary of Patients with Tumor Embolism due to Cardiac Metastasis Who were Treated Endovascularly
| Authors, year |
Age (y), sex |
NIHSS score |
Occluded vessel |
Device |
mTICI score |
mRS |
Cancer type |
| NIHSS, National Institutes of Health Stroke Scale; mTICI, modified thrombolysis in cerebral infarction; mRS, modified Rankin scale; MR, Merci retriever; CT, combined technique; SR, stent retriever; AC, aspiration catheter; NA, not available; MCA, middle cerebral artery; ICA, internal carotid artery |
| Bhatia et al.,25 2010 |
62, female |
19 |
ICA |
MR |
2a |
NA |
Breast cancer |
| Zander et al.,26 2016 |
58, male |
24 |
MCA (M2) |
SR |
3 |
6 |
Lung cancer |
| Kim et al.,27 2013 |
22, female |
4 |
MCA |
AC |
3 |
NA |
Melanoma |
| Passhak et al.,28 2018 |
40, male |
12 |
MCA |
SR |
3 |
0 |
Liposarcoma |
| Tsurusaki et al.,29 2019 |
72, male |
13 |
ICA |
SR |
3 |
0 |
Lung cancer |
| Oyama et al.,30 2020 |
34, male |
17 |
ICA |
CT |
2b |
6 |
Lung cancer (epidermoid carcinoma) |
| Yoshikawa et al.,31 2020 |
66, male |
14 |
MCA |
SR |
3 |
1 |
Lung cancer |
| Moriyama et al.,32 2021 |
64, male |
10 |
MCA |
CT |
2b |
6 |
Lung cancer |
| Magami et al.,33 2024 |
63, female |
10 |
Right MCA
Left MCA |
SR |
2b
3 |
1 |
Lung cancer |
| Tanaka et al.,34 2025 |
60s, female |
21 |
MCA |
CT |
2b |
2 |
Renal cell carcinoma |
| Present case |
50, female |
27 |
ICA |
CT |
3 |
6 |
Chondrosarcoma |
It is true that stroke patients with active cancer are more likely to develop recurrence38) and have poorer outcomes.11,39,40) Table 1 shows that 4 of the 11 patients with available postoperative prognoses died in the short term despite technically successful endovascular therapy. When excluding one patient treated with a Merci retriever on a previous day, all underwent successful revascularization using a stent retriever, aspiration catheter, or a combination of both. This suggests that tumor emboli may be more amenable to removal as a whole with modern endovascular techniques.
Given that approximately one-quarter of patients with active cancer have been reported to regain functional independence,10) it is critical to carefully assess which patients should receive aggressive interventions such as EVT. Additionally, echocardiography is essential when evaluating the etiology of stroke in these patients.
Conclusion
We experienced an extremely rare patient who had a cardiac metastasis of EMC and developed cerebral infarction due to tumor embolism, which was retrieved by EVT.
