Carcinoma arising within bilateral benign fibroepithelial tumors of the breast: a case report.

Authors

Siheng Liu, Jie Han, Yufei Wang

Published in

Frontiers in oncology. Volume 16. Pages 1966791. Epub Sep 16, 2026.

Abstract

Malignant transformation within breast fibroepithelial tumors is uncommon, and carcinoma arising within bilateral benign fibroepithelial tumors is exceptionally rare. Preoperative imaging and needle biopsy may fail to identify small malignant foci. This report aims to expand the clinical experience regarding the diagnosis and management of this rare presentation.
A 53-year-old perimenopausal woman presented with a large, painless mass in the right breast and had no family history of breast cancer. Mammography and ultrasonography demonstrated a large confluent mass in the right breast and multiple small nodules in the left breast, without typical malignant calcifications. The patient declined core needle biopsy and underwent wide local excision of the right breast mass and ultrasound-guided vacuum-assisted excision of a left breast lesion. Permanent histopathologic examination with immunohistochemistry revealed a benign phyllodes tumor containing a focal grade 1 invasive carcinoma of no special type in the right breast and adenosis with fibroadenoma containing focal low-grade ductal carcinoma in situ (DCIS)in the left breast. Both malignant foci were very small, strongly hormone receptor positive, and had low proliferative activity. Following multidisciplinary discussion, sentinel lymph node biopsy was omitted, and long-term endocrine therapy was initiated with toremifene during the perimenopausal period, with planned transition to letrozole after menopause. No recurrence was detected during 6 months of postoperative follow-up.
Occult carcinoma can arise within bilateral benign breast fibroepithelial tumors in middle-aged and older women. Imaging may lack typical malignant features, and needle biopsy may miss small malignant foci; definitive diagnosis may therefore depend on complete excision and histopathologic evaluation. Treatment should be based on surgical excision and individualized systemic therapy according to the pathologic stage and molecular phenotype, with long-term surveillance.

PMID:
42818632
Bibliographic data and abstract were imported from PubMed on 01 Oct 2026.

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