An autopsy case of TFE3-rearranged PEComa-like neoplasm with systematic embolization involving the heart.

A rare autopsy case of malignant transcription factor E3 (TFE3)-rearranged perivascular epithelioid cell tumor (PEComa)-like neoplasm is presented. An 84-year-old woman manifested multiple cerebral infarctions and repetitive embolic events in the supra mesenchymal artery (SMA), and the presence of a mobile mass in the heart's left ventricle was also revealed. Tumoral lesions were also found in a pelvic space and a right pleural cavity, and a biopsy was performed from one of the disseminated tumor masses in the right pleura. Pathological diagnosis of TFE3-rearranged PEComa-like neoplasm was defined based on the evidence of partial expression of Melan A, and strong nuclear expression of TFE3 and by detection of the Xp11.2 locus split signal with FISH. A post-mortem analysis via autopsy revealed the widespread intravascular tumors in the heart's left ventricle, supra mesenchymal vein (SMV), and partial vein. The left intraventricular tumoral mass was associated with thrombus and fibrine, and thrombotic emboli were also found in SMA, SMV, and left pulmonary arteries. Interestingly, organ-based tumor invasion accompanying desmoplastic reactions was hardly seen. The small intestine was perforated, likely due to ischemia, which resulted in suppurative peritonitis and sepsis. This was thought of as the direct cause of death. This is the first report of a precise autopsy investigation of TFE3-rearranged PEComa-like neoplasm. Tumoral localization was mostly intravascular or disseminative in the pleural cavity. Given the limited understanding of this tumoral pathophysiology, this case offers valuable insights for prompt diagnosis and effective treatment strategies.