A Fatal Case of Pulmonary Tumor Thrombotic Microangiopathy Originating From Primary Bladder Adenocarcinoma

Introduction Pulmonary tumor thrombotic microangiopathy is a rare, fatal complication of malignancy, with few reports involving bladder cancer. Case Presentation An 81‐year‐old man with chronic obstructive pulmonary disease presented with hematuria and progressive exertional dyspnea. Imaging showed an invasive bladder tumor with lymph node metastases. Echocardiography suggested pulmonary hypertension, although invasive confirmation was unavailable. Recurrent perioperative oxygen desaturation preceded fatal deterioration 2 days after transurethral resection. Autopsy revealed primary bladder adenocarcinoma, signet ring cell subtype, and microscopic pulmonary tumor emboli with fibrin thrombi, fibrous intimal thickening, and recanalization. These findings supported pulmonary tumor thrombotic microangiopathy. Distinct gastrointestinal tumors and matching bladder and metastatic morphology supported a bladder origin. Conclusion Pulmonary tumor thrombotic microangiopathy should be considered in patients with bladder tumors and progressive dyspnea. Recurrent desaturation and right heart abnormalities warrant reassessment despite preserved oxygen saturation. Autopsy vascular findings were essential to distinguish this condition from simple pulmonary tumor embolism.