Abstract
INTRODUCTION: Solid papillary carcinoma (SPC) accounts for approximately 1% of all breast cancer cases and occurs primarily in postmenopausal women. We report a rare SPC with invasion in the male breast. CASE PRESENTATION: A 73-year-old Japanese man presented with bloody nipple discharge and a palpable left breast mass. Mammography revealed a well-defined high-concentration mass. Ultrasonography scans demonstrated an intracystic 10 mm mass under the left nipple without enlarged axillary lymph nodes. A core needle biopsy revealed a ductal carcinoma with nuclear grade 1, which excluded an invasive carcinoma. Magnetic resonance imaging exhibited a 7 mm intense early enhancement in the left breast. A left mastectomy and sentinel lymph node biopsy were performed. The patient was diagnosed with pathological stage IA (T1b N0 M0) breast carcinoma, an invasive pure SPC type without neuroendocrine markers. The patient was treated with oral tamoxifen and survived without any recurrence for 12 months. CONCLUSION: Invasive SPC of the male breast may occur as a palpable mass or nipple discharge in older men and has a good prognosis.