Case Report: Early-onset Luminal B-like male breast cancer with perineural invasion

Abstract

Male breast cancer (MBC) is a rare malignancy accounting for less than 1% of all breast cancers and less than 1% of cancers in men. Compared with female breast cancer, MBC is characterized by a predominance of hormone receptor-positive luminal tumors, whereas evidence guiding individualized management remains largely extrapolated from female populations. Perineural invasion (PNI), a recognized adverse prognostic factor in several solid tumors, is uncommon in breast cancer and has rarely been reported in men. Its clinicopathological significance and therapeutic implications in male breast cancer remain poorly defined. We report a young man with stage IA Luminal B-like (HER2-negative) MBC complicated by PNI to highlight the challenges of postoperative risk stratification and adjuvant treatment decision-making.