Left Ventricular Intimal Sarcoma Masquerading as a Benign Mass.

backgroundPrimary cardiac sarcomas are rare yet aggressive, and their preoperative diagnosis is particularly challenging, as specific subtypes such as intimal sarcoma can radiologically mimic benign masses like organized thrombus. CASE SUMMARY: A 45-year-old man presented with exertional dyspnea. Transthoracic echocardiography revealed a large, calcified left ventricular mass causing outflow tract obstruction, leading to a preoperative diagnosis of organized thrombus. Postresection histopathology indicated a malignant mesenchymal tumor, and MDM2 amplification confirmed intimal sarcoma. DISCUSSION: Classic benign imaging features (calcification, avascularity) can camouflage a high-grade sarcoma. We emphasize the need to recognize specific "red flag" features and advocate for integrating MDM2 testing into the diagnostic workflow for ambiguous left-sided masses to guide lifesaving radical resection and avoid catastrophic management delays. TAKE-HOME MESSAGES: The classic imaging triad of a calcified, avascular, left-sided cardiac mass can be misleading and in rare cases may mask an aggressive intimal sarcoma. MDM2 genetic testing is critical for definitive diagnosis, guiding lifesaving radical resection over inappropriate and hazardous conservative management.