Atypical vascular lesions (AVLs) are rare flesh-colored, erythematous, or violaceous macules, patches, papules, or plaques that may occur following adjuvant radiation in breast cancer patients who have undergone conservative lumpectomy.1,2 They range in size from 1 mm to 6 cm and are most often confined to the radiation field. Presentation occurs 1 to 20 years following radiation, though the lesions most often present within 5 years.1,2 Although generally considered benign, 2 of 29 cases of AVLs progressed to angiosarcoma over a 5-year follow-up period in a retrospective clinicopathologic study.1
Atypical vascular lesions show considerable histologic and clinical overlap with radiation-induced angiosarcomas (RIAs), making differentiation between the two challenging.3,4 Mentzel et al5 compared benign, atypical, and malignant postradiation vascular lesions with nonradiation-associated angiosarcomas and found that RIAs were highly variable histopathologically, ranging from well differentiated to poorly differentiated, with atypia ranging from mild to severe. Radiation-induced angiosarcomas could be distinguished from AVLs and nonradiation-associated angiosarcomas by their oncogene amplification and protein expression profiles. Most strikingly, they found amplification of the MYC oncogene by fluorescence in situ hybridization in the nucleus of almost all the RIA cells, which was not seen in AVLs or nonradiation-associated angiosarcomas. Similarly, they found positive nuclear staining for MYC protein by immunohistochemistry in the nucleus of almost all cases of RIA but not in AVL or nonradiation-associated angiosarcomas, making MYC staining a useful diagnostic marker.5 In contrast, a study by Patton et al1 concluded that AVLs demonstrate morphologic patterns and clinical outcomes that suggest they are precursors of angiosarcoma rather than just markers of risk.
Atypical vascular lesions and RIAs usually follow a total radiation dose of 40 to 50 Gy, but RIAs typically are diagnosed later (approximately 10 years following exposure).6,7 Although RIAs are rare, they are known to be aggressive and often high grade, with a median survival of less than 5 years.6,7 Survival is poor even with radical surgical treatment.8 We present a patient with at least 29 AVLs following breast-conserving surgery and radiation and suggest the need for increased awareness of the elevated risk for RIA in patients with numerous benign AVLs.
A 43-year-old woman with a history of breast cancer who underwent breast-conserving lumpectomy and adjuvant radiation presented to dermatology upon referral from surgical oncology for multiple lesions on the right breast (Figure 1). Seven years prior to presentation she was diagnosed with grade 3 poorly differentiated invasive ductal carcinoma with lobular features in the right breast that was positive for human epidermal growth factor receptor 2 but negative for estrogen or progesterone receptors. She was given neoadjuvant treatment with trastuzumab, docetaxel, and carboplatin prior to conservation lumpectomy with adjuvant radiation. She received a total dose of 50.4 Gy in 28 fractions of 1.8 Gy each over 1 month, with a final boost of 10 Gy in 5 fractions of 2 Gy, each with local skin irritation as the only concern posttreatment.