several randomized trials have demonstrated that breast - conserving surgery followed by radiation therapy , which is called breast - conserving therapy ( bct ) , is as effective as mastectomy and should be a standard treatment for early - stage breast cancer . recently , there has been an increase in reports of angiosarcoma ( as ) after bct [ 2 , 3 , 4 ] . lymphedema - associated cutaneous as , so - called stewart - treves syndrome , was first described in 1948 by stewart and treves . herein , we report a case of as which developed after bct and a case of stewart - treves syndrome with a focus on lymphedema . in 1997 , a 62-year - old woman underwent bct with 50 gy radiation for left - sided breast cancer , categorized as stage ia . she was started on weekly intravenous paclitaxel at a dose of 100 mg / m . in may 2009 , she presented with an erythematous purplish palpable mass on the right breast ( fig . a punch biopsy revealed the invasion of spindle - shaped cells with vascular differentiation into the subcutaneous tissue ( fig . each time , further wide excisions were performed . due to these local recurrences , at 85 cycles after the administration of weekly paclitaxel therapy , the patient was switched to monthly docetaxel at a dose of 70 mg / m . since then a 64-year - old woman was diagnosed with right - sided breast cancer that was categorized as stage ia . she received no adjuvant radiotherapy because she had already been treated with chemotherapy using a combination of paclitaxel and carboplatin for ovarian cancer . in november 2011 , the patient was admitted to our hospital for evaluation of purplish ecchymosed cutaneous lesions without a palpable mass on the right breast in the setting of chronic lymphedema ( fig . a punch biopsy revealed pleomorphic spindle - shaped cells with little vascular differentiation infiltrated into the dermis ( fig . the patient was started on monthly docetaxel at a dose of 75 mg / m . in 1997 , a 62-year - old woman underwent bct with 50 gy radiation for left - sided breast cancer , categorized as stage ia . she was started on weekly intravenous paclitaxel at a dose of 100 mg / m . in may 2009 , she presented with an erythematous purplish palpable mass on the right breast ( fig . a punch biopsy revealed the invasion of spindle - shaped cells with vascular differentiation into the subcutaneous tissue ( fig . each time , further wide excisions were performed . due to these local recurrences , at 85 cycles after the administration of weekly paclitaxel therapy , the patient was switched to monthly docetaxel at a dose of 70 mg / m . since then a 64-year - old woman was diagnosed with right - sided breast cancer that was categorized as stage ia . she received no adjuvant radiotherapy because she had already been treated with chemotherapy using a combination of paclitaxel and carboplatin for ovarian cancer . in november 2011 , the patient was admitted to our hospital for evaluation of purplish ecchymosed cutaneous lesions without a palpable mass on the right breast in the setting of chronic lymphedema ( fig . a punch biopsy revealed pleomorphic spindle - shaped cells with little vascular differentiation infiltrated into the dermis ( fig . the patient was started on monthly docetaxel at a dose of 75 mg / m . many studies have demonstrated that radiation may be a major risk factor in the development of as [ 2 , 3 , 4 ] . on the other hand , case 2 suggests that chronic lymphedema is the primary risk factor for as , which was first described in 1948 by stewart and treves . radiation therapy secondarily tends to induce the development of as , since radiation therapy induces fibrosis and proliferation of lymphatic vessels via cytokines such as vascular endothelial growth factor , which is followed by subclinical chronic edema . it is suggested that axillary lymph node dissection predisposes patients to the development of as , since it is closely associated with lymphedema . the increased use of bct is likely to lead to an increase in the number of patients with as . the prognosis of as after bct is poor , with a low 5-year overall survival ( 55% ) and a low disease - free survival at 5 years ( 35% ) . therefore , breast surgeons and radiologists should be aware of skin changes in order to improve the early detection of as during the follow - up of patients who have undergone bct , and especially those treated with axillary lymph node dissection .