Primary atrial fibromyxosarcoma with multiple-system metastases: A case report

RATIONALE: Fibromyxosarcoma is common in head and neck, vessel, omentum, and reproductive system, with low-grade malignant behavior. However, primary atrial fibromyxosarcoma with highly malignant behavior is extremely rare. PATIENT CONCERNS: A 34-year-old female presented with oppression in the chest, short breath, and onset of headache as initial symptoms. The preoperative echocardiogram showed a medium-size echogenic mass close to the posterior leaflet of the mitral valve in the left atrium. DIAGNOSIS: Primary atrial fibromyxosarcoma with multiple-system metastases. INTERVENTIONS: The patient underwent surgery, and the tumor was removed completely. The diagnosis of left atrium fibromyxosarcoma was confirmed through postoperative histopathological examination. Positron emission tomography/computed tomography scan was performed, which revealed multiple metastases to left adnexa, bilateral adrenal glands, left iliacus, right lateral ventricle, and skeletal system. OUTCOMES: The patient died of cerebral hernia caused by hemorrhage from the metastatic brain tumor, 30 days after the surgery, without receiving chemotherapy or radiotherapy. LESSONS: Cardiac fibromyxosarcoma is a rare primary malignant cardiac neoplasm, probably with systemic metastases. The possibility of malignancy should be considered as differential diagnosis for cardiac mass.