Abstract PO1-21-01: A Case of High Grade Metastatic Encapsulated Papillary Carcinoma and a Look at Current Treatment Guidelines

Abstract

Abstract Background: Encapsulated papillary carcinoma is a well-documented malignancy in the world of breast surgery. It is often described as a less invasive form of breast cancer, with a more indolent clinical course. Most EPC pathology demonstrates low grade tumors, with rare findings of metastases at time of diagnosis. EPC currently accounts for 1-2% of all breast cancers. It is distinguished by its fibrovascular core, which is covered with epithelium with or without a myoepithelial layer. Despite EPC being well-recognized, current management remains controversial. Most commonly, however, it is treated and managed as an in-situ disease. Case Presentation: We present a case of a 64-year-old female who initially presented with a painless lump in her left breast, which on biopsy demonstrated DCIS involved with a papillary lesion. On excision, the patient was upstaged to IDC in a background of EPC. She then underwent re-excision with confirmed negative margins. Despite this, over the following months, the patient continued to have increased pain, swelling, and an episode of superficial thrombophlebitis. She was taken back to the OR at this time and was found to have a new mass with a large feeding vein. Pathology was significant for high grade multifocal EPC with small and large vessel lympho-vascular invasion. Lesion noted to be metachronous. Additionally, metastases to the axilla were identified, requiring an axillary dissection. Conclusion: High grade encapsulated papillary carcinoma is a rare member of the indolent papillary breast cancer family. This unusually invasive type of cancer should be treated and managed in a more aggressive fashion, like its clinically similar cousin invasive ductal carcinoma. The current management standard of treating EPC as in situ disease is not robust enough and can lead to disease recurrence and need for repeat resection and treatment. Citation Format: Nicholas Gore MD, Madeline Silva MD, Carissia Calvo-Strube MD. A Case of High Grade Metastatic Encapsulated Papillary Carcinoma and a Look at Current Treatment Guidelines [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-21-01.