# Co-existence of fibroadenoma, intraductal carcinoma and invasive ductal carcinoma in the unilateral breast mass: a case report and literature review

## TL;DR

A rare case of a breast mass containing both benign and cancerous tumors is reported, emphasizing the need for thorough evaluation and accurate diagnosis.

## Contribution

This case report highlights the rare coexistence of fibroadenoma, DCIS, and IDC in a unilateral breast mass.

## Key findings

- A 71-year-old woman had a breast mass containing IDC, DCIS, and fibroadenoma.
- The tumors showed Luminal B1 subtype with ER and PR positivity and Her-2 negativity.
- The patient completed treatment with no recurrence observed during follow-up.

## Abstract

Fibroadenoma is the most common benign breast tumor. However, the coexistence of ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) within single breast fibroadenomas is rare.

A 71-year-old woman presented with a palpable mass in her left breast, and she had a history of right-side breast cancer, which had been treated 16 years ago. Invasive ductal carcinoma was confirmed through core needle biopsy. She subsequently underwent left breast mastectomy with sentinel lymph node biopsy. Postoperative pathological examination revealed two fibroadenomas: the larger one coexisted with IDC and focal DCIS, and the small one coexisted with high-grade DCIS. Immunohistochemical analysis showed positive expression of estrogen receptor (ER) and progesterone receptor (PR), but negative expression of Her-2, demonstrating a Luminal B1 subtype (clinical stage IA). She had completed the adjuvant chemotherapy and currently received endocrine therapy. No recurrence was found during the follow-up examinations.

Coexistence of fibroadenoma, DCIS and IDC in unilateral breast mass is rare, highlighting the importance of comprehensive preoperative evaluation, optimal surgical strategy and accurate histopathological examination.