Coexistence of invasive ductal breast carcinoma and fibroadenoma

Fibroadenomas are the most common breast disease that occurs usually in young. The coexistence of an invasive ductal carcinoma and a fibroadenoma in the ipsilateral breast is extremely rare. We present the case of a 52 years woman, presented to us for an upper-outer breast lump. Breast imaging concluded to tow contiguous lesions, one of them was suspicious. She had a conservative surgery. Histology concluded to a fibroadenoma and an invasive ductal carcinoma.


Introduction
Breast cancer is the leading cause of mortality associated to female cancer among the world. Invasive ductal carcinoma is the most common pathological type. Fibroadenomas are the most common breast disease that occurs in women usually below the age of 35 years old [1]. A carcinoma can arise rarely within or in the ground of a fibroadenoma [2]. The coexistence of an invasive ductal carcinoma and a fibroadenoma in the ipsilateral breast is extremely rare which is illustrated in this case.

Patient and observation
A 52 year-old woman presented with a mass located at the left breast.
Clinical examination showed a 3cm palpable rough stiff lump located in the upper outer quadrant of the left breast and two left axillary lymph nodes. Breast ultrasound revealed a hypoechoic hypervascularized spiculated lesion which is "taller than broader" and measuring 26mm in diameter with posterior acoustic shadowing. This lesion was associated to another contiguous well-circumscribed, macrolobulated hypoechoic lesion measuring 27mm in diameter with intralesional calcification. Mammography showed a spiculated parenchymal distortion with an opaque center and thick spiculations, the second adjacent lesion was well-defined, isodense to the breast glandular tissue, with macrolobulation and central "coarse popcorn" calcifications evoking an aged fibroadenoma ( Figure 1). No distant metastasis was detected on body CT scan. The patient was treated with breast conserving surgery. The lumpectomy measured 80 × 60 × 30mm. The histological examination concluded to a fibroadenoma and a contiguous 30mm diameter infiltrating ductal carcinoma SBR Grade III. Conservative surgery was performed with axillary lymph node dissection. The final histopathological report revealed atypical infiltrating carcinoma with grade SBR III. Three axillary lymph nodes were metastatic. ER and PR were negative on immunohistochemistry.
HER2 was negative. The patient was referred for chemotherapy and radiotherapy.

Discussion
Fibroadenoma is a biphasic tumor consisting of epithelial and stromal components [1]. Recent studies identified frequent mutations in the stromal component suggesting that this tumor was primarily stromal neoplasm [3]. Breast carcinoma may arise within a benign tumor or the tumors may coexist independently [3,4]. In a review of the literature, the incidence of a carcinoma evolving within a fibroadenoma was 0.002% to 0.0125%. Only 10% of these tumors were infiltrating ductal carcinoma. The clinical and imaging findings are frequently those of benign fibroadenomas [5]. In our case, carcinomatous lesion was an infiltrating ductal carcinoma adjacent to an aged fibroadenoma. Researchers still debate about breast cancer risk and benign breast diseases. Fibroadenomas are not typically considered as a risk factor of carcinoma [6]. The authors have demonstrated the importance of proliferative character with or without atypia in the adjacent parenchyma [9]. The existence of proliferative changes in the parenchyma adjacent to the fibroadenoma elevates further the risk [5]. A study on 3567 women diagnosed with breast cancer published in April 2018 by Nutter et al found that woman with breast proliferative disease with atypia are twice exposed to have multifocal breast cancer than woman with no breast benign disease [10].

Conclusion
This case highlights the rare association in contiguity of two common breast diseases and the value of histological examination for the diagnosis of malignancy. Every woman with the diagnosis of a complex fibroadenoma particularly with a family history is more concerned by frequent mammographic screening starting at an early age.

Competing interests
The authors declare no competing interests.

Authors' contributions
All the authors contributed to the realization of this work. All authors have read and approved the final version of the manuscript.