S4108 Primary Occult Intimal Sarcoma of the Heart Initially Presenting as Gastrointestinal Polyps

Introduction: We report a 72-year-old White woman, who presented with chest pain and dyspnea. This case highlights the diagnostic challenges in identifying primary occult cardiac tumors, as the initial investigation shifted the attention towards gastrointestinal findings. Case Description/Methods: Multiple polyps were discovered along the gastrointestinal tract, with biopsies showing inflammatory polyps with a pseudosarcomatous stromal repair response. However, it was not until later, when her symptoms prompted a repeat transthoracic echo, that an intracardiac mass was identified. Once the mass was excised and identified as intimal sarcoma originating from the heart, it was determined to be the primary source of the metastatic gastrointestinal polyps, as confirmed by matching pathology and tumor marker stains. Despite the excision of the cardiac mass, it recurred a year later. Discussion: Given that gastrointestinal symptoms can be the initial manifestation of cardiac intimal sarcomas, gastroenterologists should maintain a high index of suspicion when encountering atypical polyps or malignant-appearing lesions with inconclusive biopsy results. Although cardiac intimal sarcomas are not typically linked to known genetic syndromes, this case highlights the value of early colonoscopy evaluation in symptomatic patients and possibly earlier screening for their immediate family members, facilitating earlier detection of unusual neoplasms or metastatic disease. Such proactive screening may ultimately improve clinical outcomes by identifying malignancies at a more treatable stage.