Fibroadenoma is a benign fibroepithelial tumor common in young women; the overall incidence is about 2.2%; they represent about 68% of breast masses, and 70% presented as a single mass and 10–25% as multiple masses [1]. It is composed of connective and epithelial tissues [2].
Although there is no risk related with fibroadenoma to breast cancer, very rare malignant changes can develop within the fibroadenoma [3]. Some studies have revealed that malignant transformation is seen more in complex fibroadenoma than simple one whereas another study reported that the risk is highly associated with the percentage of epithelial proliferation within the fibroadenoma rather than the presence of fibroadenoma itself [4]. Because the malignancy is rare in fibroadenoma, conservative management with follow-up is accepted except if the mass has progressed in size [5].
The incidence of a carcinoma evolving within a fibroadenoma represents 0.002 to 0.0125%, in which only 20% of these were DCIS [2], other malignancies as lobular carcinoma in situ; invasive ductal and lobular carcinomas are also seen [6, 7]. In our case, the case is considered as simple fibroadenoma with DCIS developed on top.
A recent publication considers a woman with complex fibroadenoma in the presence of a family history of breast cancer as a risk factor that should start mammographic screening at an early age [8].
The management of fibroadenoma differs according to the age of the patient. Those below 35, if the regression of the mass is noted, should consider further follow-up until the mass regressed and disappear completely. If the mass is stable by the age of 35 after 6–12 months follow-up, then excision is advised. On the other hand, if the mass has increased, immediate surgical excision is performed [9].
If the age is above 35 with a stable or increased size of fibroadenoma after a follow-up of 6–12 months, excision is advised; however, the complex fibroadenoma should be surgically removed [10]. Our case referred to a breast surgeon that decided surgical removal of the mass.
The imaging findings of carcinoma arising from a fibroadenoma were reported in few studies that demonstrate a non-circumscribe indistinct margins, and clustered microcalcifications within the mass in mammogram should raise the suspicion of malignancy while in ultrasound, a focal increase of color flow signals within the mass on color Doppler study or increase size raise suspicion of malignancy [11]. In our case, the mammogram is markedly dense, and the mass cannot be appreciated. Scattered microcalcification is noted, with no suspicious microcalcification at the anticipated site of the mass. The alarming signs were demonstrated in ultrasound that identifies the enlargement of the mass and the irregular appearance of the margin.
Typically, on MRI, fibroadenoma appears as a round or oval-shaped mass with a smooth margin. Fibroadenoma can exhibit variable enhancement; however, enhancement usually persists until the delayed phase [12]. Few reports described dynamic contrast-enhanced breast MRI (DCE-b MRI) findings of carcinoma within fibroadenoma as a mass showing a pattern of early peak enhancement in the central area and delayed rim enhancement in the periphery, and in histology, DCIS was found in the center of the fibroadenoma [13]. Others described that the area of DCIS within the fibroadenoma showed rapid initial enhancement and washout kinetics on DCE-b MRI, whereas the major part of the mass was consistent with fibroadenoma [12]. In our case, DCE-b MRI demonstrates early rapid and delayed washout enhancement in the majority of the mass and progressive enhancement of its central portion which might represent a remaining part of fibroadenoma.
