Breast cancer mimicking fibroadenomas in postmenopausal women

Fibroadenomas (FADs) are benign breast lesions usually seen in late teens less so common in postmenopausal women. This is a case series of postmenopausal patients, where breast cancer looked like fibroadenoma on imaging. The aim of this study was to identify the important role of tissue diagnosis in FAD like lesions on imaging and highlight the deceiving imaging findings.

We retrospectively reviewed the medical records of patients at our Breast unit who were treated for breast cancer under one surgeon in the period of Feb 2009 to Jan 2010. Patients underwent triple assessment as per protocol of the breast screening unit. All had fine needle aspiration and core biopsy of the lesions. Appropriate surgery was offered and the size, grade and lymph node status were evaluated and Nottingham Prognostic Index (NPI) used to predict survival.

5 patients were identified with breast cancers that had initial radiological diagnosis of fibroadenoma. All patient lesions were screen detected on NHS screening programme. One patient out of five was discharged after triple assessment and represented with a lump 18 months later. The Median age was 56 years (range 50-66 years). The mammogram showed these to be benign-looking lesions and ultrasound scans suggested fibroadenomas as reported by specialist breast radiologist. Seven lesions were identified in 5 patients. One patient had 3 lesions. Lesions size ranged between 8 mm and 25 mm on mammogram (median 14 mm) and 8-20 mm on ultrasound (range 8-20). Fine needle aspiration cytology was C5 in the two lesions, C4 in 2 and C3 in 1 lesion. Two patients had unifocal grade 3 tumours. One patient had multifocal cancer (3 cancers - in unilateral breast) all were grade 3 cancers with lymph node involvement. One patient had grade 2 cancer and 1 was found to have adenoid cystic adenocarcinoma and therefore the grade and NPI were not assessed. NPI was good in 1, moderate in 2 and poor in 1 patient.

Our case series suggested that one should have a high index of suspicion for FAD in the postmenopausal ladies and triple assessment should include thorough tissue sampling in the form of FNA and core biopsy.