We report a rare case of cellular angiolipoma of the breast in a 73-year-old woman with abnormal mammographic findings. Histopathologic examination of the tumor revealed cellular spindle cell areas associated with collapsed and patent blood vessels in a background of mature adipose tissue. A salient feature of this tumor, which was an important clue to the diagnosis, was the presence of intravascular fibrin thrombi. Immunohistochemical studies showed reactivities for endothelial and muscle markers, highlighting the obscured angiomatous component in the cellular areas of the tumor. Failure to recognize this entity may potentially lead to diagnostic pitfalls that include angiosarcoma and Kaposi's sarcoma, two of the better recognized entities in this region.