https://orcid.org/0000-0003-1882-0747
An 89-year-old woman was admitted to the Emergency Department after the acute onset of right hemiparesis and aphasia, National Institutes of Health Stroke Scale (NIHSS) of 18. She had multiple vascular risk factors including hypertension, dyslipidaemia, and prior pulmonary embolism, under long-term anticoagulation. Brain computer tomography (CT) perfusion showed a hypoperfused area in the left hemisphere (Panel A). CT angiography revealed an occlusion of the M2 segment of the left middle cerebral artery (MCA). After one pass of stent retriever (TrevoTM4 mm ×30 mm), endovascular thrombectomy (EVT) achieved complete recanalization (mTICI = 3) at 3.5 h after stroke onset (Panels B and C). An embolic fragment, measuring 1.2 cm × 1.0 cm, was retrieved and collected for histopathology. Follow-up brain magnetic resonance imaging (MRI) documented residual small embolic lesions in the left hemisphere (Panel D). After extensive diagnostic workup, stroke aetiology remained undetermined: imaging of cervical and intracranial arteries had revealed diffuse atherosclerosis without significant stenosis, transthoracic echocardiography had shown mild aortic valve degeneration and a left atrial dilatation, but no major cardioembolic sources; heart-rhythm was sinusal at long-term monitoring.
Histopathological examination of the material retrieved by EVT was informative: macroscopically, the embolus appeared white, with multiple narrow and elongated papillary fronds resembling a ‘sea anemone’ (Panel E). Microscopic analysis revealed a peculiar architecture characterized by multiple projections, constituted of dense extracellular matrix, with abundant elastic fibers and few interspersed cell nuclei, and surrounded by a single layer of endothelial cells (Panels F–L), without superimposed thrombosis. The findings were compatible with an embolized cardiac papillary fibroelastoma, a benign primary cardiac neoplasm that can easily embolize. In up to 30% of ischaemic stroke patients, the cause of stroke remains unrecognized despite extensive diagnostic workup. Analysis of the cerebral thrombus retrieved by EVT represents a significant adjunctive tool for aetiological investigation in stroke medicine.
(Panel A) T max map on CT perfusion shows hypoperfused brain tissue in the vascular territory of the left MCA (in blue). (B) Occlusion of the proximal M2 segment of the left MCA is confirmed by the first angiographic series (white arrow). (C) Final angiographic series shows complete vessel recanalization (white arrows) after EVT . (D) Follow-up brain MRI shows multiple small embolic lesions in the left hemisphere. (E) The specimen retrieved by EVT reveals a curious anemone-like gross appearance. (F) Overview of a section of the formalin-fixed paraffin-embedded specimen after haematoxylin and eosin (H&E) staining. Note the numerous branching papillary fronds, composed of abundant fibroelastic matrix. Magnification of the small black box area is shown in (G). (H) Masson's Trichrome staining highlights (in blue) the fibroelastic composition of the papillary projections; the magnified detail of the small blue box area, shown in (I), documents the presence of a single layer of cells surrounding the projections, while few interspersed nuclei are found within the fibroelastic matrix. (L) Anti-CD34 immunohistochemistry staining confirms (in brown) the endothelial lining of the projections. Scale bars (E–L): 5 mm, 2 mm, 300 µm, 1 mm, 300 µm, 100 µm.
Conflict of interest: The authors have submitted their declaration which can be found in the article Supplementary Material online.
Author notes
Davide Strambo and Marco Bacigaluppi contributed equally to this work.
