EP.TH.3Male Breast Cancer: A Series of Three Extremely Rare Cases

Aims Male breast cancer (MBC) is rare and accounts for 1% of all breast cancers. We present a case series of three very rare histological subtype MBC within one year in a UK hospital. Methods We retrospectively identified all MBCs from the local breast cancer database. Their presentations, radiology and histopathology were analysed. Results Three MBCs were identified from 2019 to 2020. A healthy 28-year-old presented with a right breast lump. Ultrasound (USS) revealed a partially cystic 15mm U3 lesion. Mammography (MMG) was suggestive of gynaecomastia (M2). Biopsy was inconclusive. Diagnostic excision revealed Papillary Ductal Carcinoma in Situ (DCIS) with involved margin. Mastectomy and Sentinel Node Biopsy (SNB) confirmed low-grade Papillary DCIS. A 48-year-old with background of hyperlipidaemia presented with a 2-year history of left axillary lump. PET CT demonstrated an FDG-avid lesion. USS showed a superficial U3 28mm lesion. MMG showed a 34mm density (M4). Biopsy identified Mucinous Carcinoma. Wide Local Excision and SNB confirmed grade 2 Mucinous Carcinoma. A 75-year-old with history of cardiac disease, COPD and Type 2 Diabetes, presented with a right retro-areolar lump. MMG identified a 47mm mass (M4). USS showed a 41mm cystic lesion with wall thickening (U4). Cytology was inconclusive. Biopsy identified intra-cystic papillary carcinoma. Mastectomy and SNB confirmed intra-cystic papillary carcinoma. All three histological subtypes are extremely rare and account for less than 4% of all MBCs. Conclusions MBC is rare but increasing in incidence. More research and awareness are needed to minimise delays in diagnosis and treatment even in young men.