RADIOLOGY—CASE REPORT Magnetic resonance imaging appearances in primary and secondary angiosarcoma of the breast Ailbhe C O’Neill, 1 Clare D’Arcy, 2 Enda McDermott, 3 Ann O’Doherty, 1 Cecily Quinn 2 and Sorcha McNally 1 Departments of 1 Breast Radiology, 2 Pathology and 3 Breast Surgery, St. Vincent’s University Hospital, Dublin, Ireland AC O’Neill MD; C D’Arcy MD; E McDermott MD; A O’Doherty MD; C Quinn MD; S McNally MD. Correspondence Dr Ailbhe O’Neill, Radiology Specialist Registrar, Department of Breast Radiology, St. Vincent’s University Hospital, Elm Park, Dublin 4, Ireland. Email: ailbheconeill@yahoo.co.uk Conflict of interest: None. Submitted 10 March 2013; accepted 3 June 2013. doi:10.1111/1754-9485.12100 Summary Angiosarcomas are malignant tumours of endovascular origin. They are rare tumours accounting for 0.04–1% of all breast malignancies. Two different forms are described: primary, occurring in young women, and secondary angiosarcoma, which occurs in older women with a history of breast- conserving surgery and radiation therapy. Imaging findings on mammogra- phy and ultrasound are non-specific, but magnetic resonance imaging with dynamic contrast enhancement is more informative. We present two cases – one of primary and one of secondary angiosarcoma – and review the imaging findings. Key words: angiosarcoma; breast cancer; magnetic resonance imaging; mammography. Introduction Angiosarcomas are malignant tumours of endothelial cells lining vascular channels. Angiosarcoma of the breast is rare, accounting for 0.04–1% of all breast malignancies. 1–3 Primary angiosarcoma commonly occurs in young women, and secondary angiosarcoma occurs in older women with a history of breast- conserving surgery and radiotherapy. Imaging findings on mammography and ultrasound may be non-specific. Magnetic resonance imaging (MRI) demonstrates low signal intensity on T1W imaging and high signal intensity on T2W imaging due to the vascular endothelial origin of the tumour. Dynamic vas- cular phase imaging can show rapid enhancement with washout kinetics in high-grade tumours, but more com- monly demonstrates plateau or persistent enhancement kinetics. 2,4,5 Case 1 A 33-year-old woman presented with a left breast mass. Mammogram demonstrated heterogeneously dense breast parenchyma with no mass, microcalcification or architectural distortion. Targeted ultrasound of the pal- pable region demonstrated a 3.5-cm mixed echogenic mass that was predominantly hyperechoic (Fig. 1). Axil- lary ultrasound was normal. Three 14-gauge core biop- sies were taken at the time of ultrasound. Pathology demonstrated atypical vascular channels lined by mildly atypical endothelial cells positive for vascular endothelial marker CD31, consistent with a well-differentiated angiosarcoma. Dynamic contrast-enhanced MRI of both breasts with a 1.5 T whole body imager (Siemens Magnetom Avanto, Forchheim, Germany) and dedicated breast coils dem- onstrated an irregular 3.9-cm mass that was of low signal intensity on T1W imaging, high signal intensity on T2W imaging and visible on the maximal intensity pro- jection image (Fig. 2). The mass demonstrated irregular heterogeneous enhancement on dynamic vascular phase imaging (Fig. 3) with plateau enhancement kinetics. Additional imaging examinations excluded metastatic disease. The patient underwent mastectomy with imme- diate reconstruction. Case 2 A 63-year-old postmenopausal woman presented with a left breast cutaneous mass, 13 years after left breast wide local excision and adjuvant radiotherapy for invasive ductal carcinoma. Mammogram performed 7 Journal of Medical Imaging and Radiation Oncology 58 (2014) 208–212 © 2013 The Royal Australian and New Zealand College of Radiologists 208