The high-grade undifferentiated pleomorphic cardiac sarcoma (UPS) is the second most common primary malignancy in the heart; usually remains asymptomatic, until they produce a mass effect or embolization. A 47-year-old female previously healthy was admitted for a 7-day history of progressive dyspnea. At physical examination, there was mitral regurgitant murmur Grade III and bilateral crepitation rales; the electrocardiogram detected sinus tachycardia (Fig. 1A) and X-ray showed Grade II venocapillary hypertension and pleural effusion (Fig. 1B). The echocardiogram revealed an intracardiac mass in the left atrium of 36 mm × 48 mm, protruding through the mitral valve, conditioning moderate stenosis and severe insufficiency (Fig. 1C-E). Surgical treatment was realized with resection of the tumor, partial resection of the posterior wall of both atrial and interatrial septum, and mitral commissuroplasty. The histological sections showed a solid-appearing neoplastic proliferative lesion with lax isolated areas of myxoid appearance, short cellular bundles, and branched vessels with extensive myocardial infiltration and infiltration of the valvular tissue (Fig. 2A-C). Thoracoabdominopelvic tomography showed no evidence of metastatic disease. Treatment was started with chemotherapy, but she had progressive deterioration and died 3 months later. Cardiac sarcoma has an incidence of ~ 1.7% of cases; survival at 10 years is 90% in low-grade sarcomas, 60% with intermediate grade, and 20% with high degree¹. The treatment is surgical resection followed by chemotherapy², however, the invasive nature of UPS makes it difficult to obtain surgical margins without tumor activity, associated with relapse and poor short-term prognosis³.

Figure 1 Electrocardiogram and multimodality imaging approach of undifferentiated pleomorphic cardiac sarcoma. A: 12-lead electrocardiogram shows sinus tachycardia; B: chest X-ray with Grade II venocapillary hypertension and pleural effusion; C: four chambers image by transthoracic echocardiogram, showing intracardiac mass (arrow) located in the left atrium; D: transesophageal echocardiogram confirms mass in the left atrium (solid arrow) adhered to the posterior wall of 48 mm × 34 mm and E: Doppler color showed obstruction of the left ventricle inflow tract (dashed arrow). 

Figure 2 Histological sections of undifferentiated pleomorphic cardiac sarcoma. A: the neoplastic cells have an epithelioid or spindle cell appearance with pleomorphic nuclei, atypical mitosis, and scarce lymphocytic infiltrate (HE, 400 ×); B: extensive myocardial infiltration is shown by pleomorphic neoplasm with a solid pattern (HE, 100 ×); C: immunohistochemical staining with positive cytoplasmic anti-vimentin antibody (ocher color) in most of the neoplastic cells (100 ×). HE: Hematoxylin-eosin.