Invasive Papillary Carcinoma of the Male Breast Misdiagnosed as Fibroadenoma on FNAB.

Male breast cancers constitute less than 1% of all the breast cancers. Papillary carcinoma is a very rare tumour of the male breast. Due to rarity, Fine Needle Aspiration Biopsy (FNAB) findings of papillary carcinoma in male breast are seldom reported. A 55-year-old male presented with a lump in the left breast of two years' duration. FNAB was reported as fibroadenoma. Histopathological examination of the excised breast lump revealed invasive papillary carcinoma. Immunohistochemistry showed expression of pancytokeratin, oestrogen receptor, and progesterone receptor. Negative immunostaining was seen for HER2, p53, 34βE12, and CD34. Ki-67 proliferative index was 5%. We have discussed cytological findings of invasive papillary carcinoma and its differential diagnoses. Cytopathologists must be aware of cytologic findings of invasive papillary carcinoma of the male breast.