Encysted Papillary Carcinoma of the Breast (EPC): A Follow-up Study to Investigate the Role of Sentinel Lymph Node Biopsy

Background: Encysted papillary carcinoma (EPC) is a rare breast neoplasmthat mainly affects postmenopausal women. The purpose of this study was toexamine whether a sentinel node biopsy would be deemed necessary in patientswith a diagnosis of EPC and to determine if evidence of invasiveness can bediagnosed on a core needle biopsy with sufficient confidence to guide decisionmaking for upfront axillary SLNB.Methods: The available data of patients with EPC of the breast were reviewedat a tertiary breast cancer unit over a period of ۱۰ years (۲۰۰۹-۲۰۱۹) and theconcordance between core needle biopsy and final histology was assessed. We alsocarried out a detailed review of the available literature to inform best practiceguidance for management of the axilla.Results: During the study, a total of ۳۷ EPC patients were identified, of whom۱۰ were excluded as they declined further treatment, providing us a study sampleof ۲۷ patients. The median age at diagnosis was ۷۲ years (range ۴۷-۹۷) and thevast majority of patients (۹۶%) were Estrogen Receptor (ER) positive. Of the ۲۷patients treated, ۱۷ (۶۳%) underwent a diagnostic axillary Sentinel Lymph NodeBiopsy (SLNB). On the final histology, ۱۳/۲۷ (۴۸%) proved to have invasivedisease. A total of ۵ (۱۸%) patients had evidence of metastasis in the axillary nodes,of whom only ۷% had macro-metastatic disease that warranted further axillarytreatment. None of the treated patients had evidence of recurrence or distantmetastatic disease, to date (median of ۵ years of follow up).Conclusion: Encysted papillary carcinoma is associated with a low incidenceof axillary node involvement. SLNB should only be carried out when there isevidence of invasive cancer. An algorithm was developed to help guidemanagement of the axilla in cases diagnosed with EPC on diagnostic core needlebiopsy.