| Myxoma | Organizing thrombus |
| A pedunculated growth with a smooth Glistening and transparent surface | A stratified and friable surface |
| Soft, gelatinous consistency | Granular, opaque exterior |
| Absence of hemosiderin | Abundance of hemosiderin and fibrin |
| Mucin positive | Absence of mucin |
| Covered with intact endocardium | A wide base with underlying endocardial lesion |
| Rooted into myocardium | A distinct demarcation from the myocardium |