Endovascular thrombectomy (EVT) is a treatment option in patients with a cerebral venous thrombosis (CVT) who deteriorate despite anticoagulant treatment. Assessment of thrombus composition in CVT may provide insights into the pathophysiology of the disease and suggest new therapeutic strategies. A 47-year-old woman (smoking habit and estradiol/progesterone-releasing intra-uterine device) diagnosed with massive CVT underwent EVT (complete recanalization via aspiration catheter and stentriever) due to acute-onset left-sided weakness and dysarthria despite 72 h of full-dose subcutaneous low-molecular heparin. Two main reddish clots (maximum diameter 15 mm) were retrieved. Microscopic assessment showed an erythrocyte-rich thrombus (83.9% of entire thrombus surface) with layers of platelets/fibrin (lines of Zahn: 13.9% fibrin and 38.5% platelet [CD61+]). The immunological profile was dominated by neutrophils (30% MPO+), with neutrophil extracellular traps (NETs) in 1.9% of thrombus surface. T- (CD3+), B-lymphocytes (CD20+), and monocytes/macrophages (CD68+) were rather rare (2.2%, 0.7%, and 2.0% respectively). We found no evidence (0.0%) of hemosiderin and endothelial cells (CD34+). Full clinical recovery occurred prior to discharge. This is the first case report of a CVT with histologic assessment of the thrombus retrieved via EVT. Evaluating thrombi in CVT can provide key insights into disease pathophysiology and guide treatment advancements.