About 90% of lymphedema-associated angiosarcomas occur in the arms of women who have undergone modified radical mastectomy with axillary lymph node dissection for breast cancer. This complication is seen in less than 1% of women who are alive for 5 years or more after mastectomy. The incidence has fallen further recently due to increased used of more conservative surgical treatment of both the breast and the axilla. The patients are usually in 6th to 8th decade of life who develop significant lymphedema of arm post-surgery. There may or may not be history of radiation therapy; however, chronic lymphedema is a constant feature. The latent period for the development of angiosarcoma ranges from 5 to 25 years. The tumor consists of small-caliber vessels lined by atypical endothelial cells in the skin and soft tissues. The vessel lumens may be empty or filled with clear fluid or red blood cells. Well-differentiated lesions (such as this example) show anastomosing vascular channels lined by minimally atypical endothelial cells. The diagnosis in such cases is based on infiltrative growth pattern rather than cytologic atypia.