DP23 A vanishingly rare case of angiosarcoma

Abstract

We present a case report and literature review of spontaneously regressing angiosarcoma. A 74-year-old woman presented with an 18-month history of a progressively enlarging purple nodule upon the right forearm. Her past medical history was significant for a previous right-sided breast cancer treated 8 years prior with neoadjuvant chemotherapy, mastectomy, lymph node dissection, radiotherapy and adjuvant trastuzumab. The area irradiated during radiotherapy did not include the right arm. Incisional biopsy demonstrated pleiomorphic endothelial cells positive for the vascular markers CD31 and CD34, and overexpression of c-Myc and D2-40, confirming a diagnosis of angiosarcoma arising on a background of chronic lymphoedema (Stewart–Treves syndrome). Following diagnostic biopsy, the lesion regressed, with only a surgical scar visible with no palpable induration. The absence of activity on positron emission tomography–computed tomography scan confirmed complete spontaneous regression. She remained disease free for 24 months, before local recurrence prompted paclitaxel chemotherapy, with excellent clinical response. Stewart–Treves syndrome is the development of aggressive lymphangiosarcoma in areas affected by chronic lymphoedema. In patients with breast cancer undergoing radical mastectomy, the 5-year risk is between 0.07% and 0.45%. Spontaneous regression is vanishingly rare. It is defined as the partial or complete disappearance of a malignant tumour in the absence of treatment, or, following treatment, considered to be inadequate to influence the growth of neoplastic tissue. Only eight other cases of spontaneously regressing angiosarcomas are reported in the literature, with follow-up ranging from 6 months to 5 years. There are also two reports of initial spontaneous regression, but subsequent progression after 6 and 7 months, respectively. The mechanisms behind regression are unclear; however, other authors have suggested immunogenicity, imbalance of pro- and antiangiogenic factors, and epigenetic alterations as possible explanations. Despite the existing literature, our case highlights the risk of delayed recurrence and a need for close ongoing surveillance.