Abstract
A breast mass in women often presents a diagnostic challenge due to the diversity in the diagnosis. We herein report a rare variant of breast carcinoma, an invasive apocrine carcinoma (AC), in an elderly woman where the breast mass clinically mimicked phyllodes tumour. Immunohistochemistry (IHC) showed the tumour as triple-negative and also negative for androgen receptor (AR). Gross cystic disease fluid protein (GCDFP-15) was strongly and diffusely positive. It is an exceptional finding. It implies its significance as a diagnostic marker of AC of the breast. The accurate diagnostic criteria of AC are still lacking. Patients with breast lumps offer unique challenges and enormous responsibility to primary and family care physicians.