Fibroadenoma in axillary accessory breast mimicking carcinoma of unknown primary; a case report with literature review

IntroductionAccessory breast (AB) is extra and ectopic breast tissue. Fibroadenoma (FA) in AB is a rare finding. This study aims to present a case of FA in axillary AB mimicking carcinoma of unknown primary (CUP).Case reportA 38-year-old female presented with a mass in her right axilla.

She had a mass in her right breast for 5 years. She previously had a left breast lumpectomy for a benign condition. The lump in her axilla was palpable and hard.

Ultrasound showed an oval lymph node in the level I axilla (12*6mm) with blurred and unclear fatty hilum, suspicious for malignancy. Magnetic resonance imaging revealed an oval lesion (12*7mm) in the level I axilla with no fatty hilum and with heterogeneous enhancements, suggesting abnormal nodes. Fine needle aspiration of the axillary mass suspected CUP.

But core biopsy resembled FA. Both masses in the right axilla and breast were surgically excised …