Acute Ischemic Stroke due to Undifferentiated Sarcoma: A Case Report and Literature Review.

Tumor emboli due to a sarcoma are usually confirmed by an autopsy or operative findings. A sarcoma embolus in an acute stroke patient is rare. We herein report a 37-year-old man with acute stroke caused by internal carotid artery occlusion who underwent embolectomy. A histopathological analysis of an embolus obtained with a mechanical retriever device was diagnosed as undifferentiated sarcoma. This is the first case of extracardiac sarcoma extraction via mechanical retrieval performed during intervention for acute ischemic stroke. A histopathologic evaluation with embolectomy is important for diagnosing tumor emboli.

Introduction

Stroke caused by large-vessel occlusion due to tumor emboli is uncommon. Tumor emboli are usually confirmed by an autopsy or operative findings (1). A few reported patients with stroke due to tumor emboli were diagnosed by a histological examination after mechanical endovascular embolectomy. Verifying an extracardiac tumor embolus, especially sarcoma, is very rare.

Case Report

A 37-year-old right-handed man experiencing migraine presented with sudden-onset left-sided limb weakness and was immediately admitted to our hospital. He had left hemiplegia with neglect, mild dysarthria, and a National Institute of Health Stroke Scale (NIHSS) score of 13. Magnetic resonance imaging of the brain revealed acute infarcts in the right middle cerebral artery area. Subsequent magnetic resonance angiography and carotid duplex scanning showed an occluded right internal carotid artery. Intravenous recombinant tissue plasminogen activator (0.6 mg/kg) was administered 120 minutes after symptom onset, without neurological improvement. Endovascular treatment was chosen because his symptoms suggested a clinical radiological mismatch (Figure A and B).

Figure.

(A) Pre-procedural diffusion-weighted imaging shows right middle cerebral artery area infarcts. (B) T2-fluid attenuated inversion recovery imaging suggested a clinical radiological mismatch. (C) Right common carotid artery angiography shows occlusion of the right internal carotid artery. (D) Successful recanalization (TICI grade 2b). (E) Specimen on the mechanical clot retriever. (F) The retrieved embolus contains atypical cells with pleomorphic nuclei (Hematoxylin and Eosin staining). (G) The immunohistochemical findings were positive for vimentin. (H) Positron emission tomography-computed tomography revealed the uptake at the aortic root.

Cerebral angiography showed right internal carotid artery proximal occlusion. Mechanical endovascular embolectomy with 3 passes of a TrevoⓇ ProVue Retriever 4×20 mm (Stryker, Kalamazoo, USA) was successful, achieving partial recanalization with thrombolysis in cerebral infarction (TICI) grade 2b (Figure C-E).

A pathological examination of the embolus revealed atypical cells with pleomorphic nuclei (Figure F) that were immunohistochemically positive only for vimentin and desmin (Figure G), suggesting undifferentiated sarcoma.

Transesophageal echocardiography showed no cardiac tumor. Positron emission tomography-computed tomography revealed the uptake at the aortic root, indicating that the embolus originated from an occult aortic sarcoma (Figure H). One month after the stroke, his NIHSS score was 4, and his modified Rankin Scale score was 2. He was discharged on day 54 and later prescribed proton therapy for the sarcoma.

Discussion

To our knowledge, this is the first case of extracardiac undifferentiated sarcoma extraction via mechanical retrieval performed during acute ischemic stroke intervention. Undifferentiated sarcomas are rare and are often diagnosed by an autopsy. In our case, a histopathological analysis of the embolus obtained from the mechanical retriever device was diagnostic of an undifferentiated sarcoma. Thus, mechanical embolectomy may be useful for evaluating tumor-induced acute large-vessel occlusions in order to obtain a histological diagnosis.

Several trials have demonstrated the benefit of endovascular therapy for acute stroke patients with large-vessel occlusion (2), although the embolectomy-retrieved emboli were not sufficiently investigated histopathologically. As the appearance of the embolus in our case could not be macroscopically distinguished from that of a common thrombus, it was difficult to diagnose it as a tumor embolus without a routine pathological examination. As reports of tumor emboli extraction due to mechanical retrieval in acute ischemic stroke are important, we explored recently reported stroke patients with tumor emboli treated with endovascular embolectomy (Table). Of the 14 cases, 10 (71%) were of cardiac origin, 6 of which (60%) were cardiac myxomas. Cardiac origin is among the most frequent origins of intracranial tumor emboli (3). The occlusion sites were treated with clot retrieval (n=10) and aspiration embolectomy (n=5) devices. Altogether, 12 (85%) cases achieved successful recanalization (TICI 2b-3). The extracardiac tumors included breast cancer, melanoma, and lung cancer (4-6). In these cases, the primary lesion had already been confirmed before embolectomy, whereas in our case, it was diagnosed after embolectomy.

Table.

Summary of Reported Cases with Histological Confirmation of Cardiac and Non-cardiac Tumor Causing Stroke with Endovascular Embolectomy.

Case		Tumor types		Primary origin		Age/sex		Initial NIHSS		Site of occlusion		Treatment modalities		Recanalization		Clinical outcome		Reference
Cardiac tumor
1		Papillary fibroelastoma		Unknown		64/ M		16		Right M1		Solitaire®		TICI 3		NIHSS 3		[7]
2		Myxoma		Unknown		45/ NA		22		Left M1		TPA + Solitaire® + Trevo® + intracranial stent		TICI 0		NIHSS 19, mRS 4		[8]
3		Myxoma		Unknown		34/ NA		26		Left M1, A2		Solitaire®		TICI 3		NIHSS 3, mRS 2
4		Myxoma		Unknown		46/ M		NA		Left carotid T		TPA+Forced suction thrombectomy (Optimo® + Penumbra®)		TICI 2b		Left eye blindness		[9]
5		Myxoma		Unknown		34/ M		9		Right M1 proximal		TPA + Merci®		TICI 3		mRS 2		[10]
6		Papillary fibroelastoma		Unknown		62/ M		24		Left M1		TPA + Solitaire®		TICI 2b		NIHSS 10, mRS 3		[11]
7		Unclassified sarcoma		Known		55/ M		22		Right distal ICA		Penumbra®		TICI 3		Improved (details unknown)		[12]
8		Myxoma		Unknown		4/ M		16		Left M1		TPA+Solitaire®		TICI 3		Only mild weakness		[13]
9		Myxoma		Unknown		70/ M		11		Left carotid T, M1,M2		TPA + Penumbra® + Trevo®		TICI 2b		NIHSS 1, mRS 2		[14]
10		Papillary fibroelastoma		Unknown		75/ M		18		Left M1		Penumbra®		TICI 3		Improved (details unknown)		[15]
Non-cardiac tumor
11		Breast tumor		Known		62/ F		19		Left PCoA, M1, A1		Merci®		No flow through the MCA		Motor aphasia, right hemiplegia		[4]
12		Melanoma		Known		22/ F		4		Left MCA		Forced suction thrombectomy		TICI 3		NIHSS 1		[5]
13		Lung adenocarcinoma		Known		69/ F		16		Right M1		Mechanical clot retrieval		TICI 2b or 3		Death		[6]
14		Undifferentiated sarcoma		Unknown		37/ M		13		Right proximal ICA		TPA + Trevo®		TICI 2b		NIHSS 4, mRS 2		Present case

F: female, ICA: internal carotid artery, NA: not available, NIHSS: National Institute of Health Stroke Scale, M: male, MCA: middle cerebral artery, mRS: modified Rankin Scale, PCoA: posterior communicating artery, TICI: Thrombolysis in Cerebral Infarction, TPA: tissue plasminogen activator

In conclusion, a histopathological evaluation following embolectomy is important for diagnosing tumor emboli. Although embolectomy for tumor emboli appears to be effective and relatively safe, further studies are needed to verify our results.

Ethics approval was provided by the Ethics Committee of Ichinomiya Nishi Hospital, Japan.

The authors state that they have no Conflict of Interest (COI).