Imaging Features Following Breast Explant Surgery: A Pictorial Essay

Breast implants can be removed with breast explantation surgery (BES) for various reasons, including patient dissatisfaction, capsular contracture, implant infection or rupture, breast implant-associated anaplastic large cell lymphoma, and a recently emerging phenomenon called breast implant illness. There is very limited data on the imaging appearance after BES. A retrospective chart review was performed for patients with BES findings on imaging reports for the period between October 2016 and October 2021. When assessing BES techniques, a key element is determining whether the implant’s fibrous capsule requires removal. The second important question is if the patient requires an additional aesthetic procedure after BES. BES techniques include capsulotomy, and partial, total, or en bloc capsulectomy. Adjunctive aesthetic or reconstructive procedures after BES include fat grafting, mastopexy, augmentation, and reconstruction with flaps. The majority of post-BES breast imaging findings are related to the surgical scar/bed, thereby confirming that the type of explantation surgery is important. Imaging findings after BES include focal and global asymmetries, architectural distortions, calcifications, calcified and non-calcified fat necrosis, masses, hematomas, seromas, capsular calcifications, and silicone granulomas. Most importantly, since these patients have residual breast tissue, paying attention to imaging features that are suspicious for breast cancer is necessary.


Introduction
Breast implant procedures are commonly performed as cosmetic surgical procedures [1]. Breast implants may also be placed for breast reconstruction following mastectomy in women with breast cancer. Like every surgical procedure, breast implant placement has side effects and complications. The most common complications of breast implants are capsular contracture, implant rupture, breast implant-associated anaplastic large cell lymphoma (BIA-ALCL), and a recently emerging phenomenon in the literature called breast implant illness [2][3][4][5][6][7][8]. Breast implants can be removed with or without reimplantation with breast explantation surgery (BES).
In the era of radiologists being consultant physicians, it is the breast imagers' responsibility to be informed about BES in order to differentiate between benign post-surgical changes and findings suspicious for breast cancer. The imaging appearances after breast implant-based reconstruction and breast augmentation surgeries are well described in the literature [9][10][11][12][13]. In contrast, there is very limited data on the imaging appearance after BES. Hayes et al. described the mammographic findings after the removal of breast implants in 1993 [14]. In 1995, Soo et al. described seromas in residual fibrotic capsules on mammography and ultrasound after BES [15]. No papers were found in the literature with a systematic approach to the imaging findings after BES, including mammography, ultrasound, and magnetic resonance imaging (MRI). In the ideal situation, comparison of images before implantation surgery, while the implant is in place, and after BES would be helpful for the radiologist. Often pre-implant, implant, and prior explant images are not available, and it is important for the radiologist to recognize typical BES findings in order to prevent unnecessary follow-ups or biopsies. In summary, despite increasing data and awareness on breast implant-related complications that may require BES, there is limited data on the imaging findings after BES. In this paper, we discuss BES techniques and describe the imaging findings following BES.

Breast Explantation Surgery Techniques
There are different BES techniques according to patients' preferences and needs. The most important question to ask in BES is the removal of the fibrous implant capsule. The second important question is if the patients require or want additional procedures following explantation. These surgeries include capsulotomy, partial vs. total vs. en bloc capsulectomy, and BES with adjunctive aesthetic or reconstructive procedures, including fat grafting, mastopexy, and reconstruction with flaps [16][17][18].
Capsulotomy involves an incision through the periprosthetic capsule. Partial or anterior capsulectomy involves excising a portion of the capsule, mostly the anterior capsule, and leaving a portion of the capsule, usually the posterior aspect, intact. The total capsulectomy procedure removes the entire capsule.
En-bloc resection is often a misused term that means cancer removal in a BIA-ALCL diagnosed patient with removal of the implant, complete capsule in conjunction with any associated mass and a rim or margin of surrounding healthy tissue [19].
Capsulectomy is usually performed through existing incision scars, which have been used for cosmetic or reconstructive purposes. Surgeons at times need to extend those incisions in order to optimize visualization and safely perform removal of the portion or the entire capsule ( Figure 1). For patients with retropectoral implants, if total capsulectomy is performed, surgeons need to pay particular attention to the posterior layer of the capsule, which is often adherent to the anterior chest wall, in order to avoid iatrogenic pneumothorax.
The decision regarding removing the capsule mostly depends on the underlying diagnosis, including BIA-ALCL, the degree of capsular contracture, patient goals and expectations, surgical planning, and intraoperative findings. Silicone implant rupture with a thickened capsule and/or silicone embedded into the capsule may also require capsulectomy.

Findings
Imaging features after explantation surgery vary depending on the cause of the explantation, the BES technique, and the time since the explantation surgery. Radiologists working mostly with aesthetic surgeons may see post-explantation findings, and radiologists working at large referral cancer centers might see post-explantation findings along with findings due to breast conservation therapy and/or oncoplastic rearrangement.
The majority of the findings are related to the surgical scar/bed, thus identifying that the prior explantation surgery is important if it is not given as a history. Findings include focal and global asymmetries, architectural distortions, breast calcifications, calcified and non-calcified fat necrosis, masses, hematomas, seromas, capsular calcification, and silicone granulomas. The severity of the above findings is usually proportional to the time elapsed since BES. Most importantly, since these patients have residual breast tissue, paying attention to features suspicious for breast cancer is necessary. After BES, the remainder of the breast mound is often addressed with breast contouring and/or volume restoration techniques involving mastopexy, fat grafting, augmentation with flaps, or new implants.

Findings
Imaging features after explantation surgery vary depending on the cause of the explantation, the BES technique, and the time since the explantation surgery. Radiologists working mostly with aesthetic surgeons may see post-explantation findings, and radiologists working at large referral cancer centers might see post-explantation findings along with findings due to breast conservation therapy and/or oncoplastic rearrangement.
The majority of the findings are related to the surgical scar/bed, thus identifying that the prior explantation surgery is important if it is not given as a history. Findings include focal and global asymmetries, architectural distortions, breast calcifications, calcified and non-calcified fat necrosis, masses, hematomas, seromas, capsular calcification, and silicone granulomas. The severity of the above findings is usually proportional to the time elapsed since BES. Most importantly, since these patients have residual breast tissue, paying attention to features suspicious for breast cancer is necessary.

Global Asymmetry
Global asymmetry is described as a large amount of fibroglandular density tissue over a substantial portion of the breast and judged relative to the corresponding area in the contralateral breast. BES can cause global asymmetry in the bilateral breasts due to differences in the granulation response of the breast tissue after surgery ( Figure 2).

Architectural Distortion
Architectural distortions can be seen in BES patients due to focal areas of fibrosis. Since architectural distortion is a suspicious finding, further evaluation with spot compression images or tomosynthesis is usually suggested (Figure 3).

Global Asymmetry
Global asymmetry is described as a large amount of fibroglandular density tissu over a substantial portion of the breast and judged relative to the corresponding area i the contralateral breast. BES can cause global asymmetry in the bilateral breasts due t differences in the granulation response of the breast tissue after surgery ( Figure 2).

Figure 2.
A 79-year-old woman with BES changes. Bilateral CC (above) and MLO (below) view demonstrate more dense tissue from post-BES changes on the right (ovals) compared to left breas Note that right breast is smaller than the left breast.

Figure 2.
A 79-year-old woman with BES changes. Bilateral CC (above) and MLO (below) views demonstrate more dense tissue from post-BES changes on the right (ovals) compared to left breast. Note that right breast is smaller than the left breast.

Architectural Distortion
Architectural distortions can be seen in BES patients due to focal areas of fibrosis. Since architectural distortion is a suspicious finding, further evaluation with spot compression images or tomosynthesis is usually suggested (Figure 3).

Asymmetries and Masses Anterior to the Pectoralis Major Muscle
Asymmetries and masses anterior to the pectoralis major muscle are common findings following BES. These findings are often seen in patients with a history of subglandular implants. Post-surgical findings with focal linear asymmetries are usually secondary to fibrosis (Figure 7). Hematomas and seromas may be seen on mammography as large dense masses ( Figure 8). Ultrasound is helpful in showing the typical features of hematomas and seromas (Figure 9). Developing masses in patients who are status post BES should be carefully evaluated with mammography and ultrasound. Figure 10 shows developing masses in the region of the BES scar. A subsequent ultrasound showed cysts.

Asymmetries and Masses Anterior to the Pectoralis Major Muscle
Asymmetries and masses anterior to the pectoralis major muscle are common findings following BES. These findings are often seen in patients with a history of subglandular implants. Post-surgical findings with focal linear asymmetries are usually secondary to fibrosis (Figure 7). Hematomas and seromas may be seen on mammography as large dense masses (Figure 8). Ultrasound is helpful in showing the typical features of hematomas and seromas ( Figure 9). Developing masses in patients who are status post BES should be carefully evaluated with mammography and ultrasound. Figure 10 shows developing masses in the region of the BES scar. A subsequent ultrasound showed cysts.

Implant Capsule/Calcifications
In some cases, it is possible to see a residual implant capsule ( Figure 11). The capsule may calcify in the expected prepectoral location (Figure 12).

Implant Capsule/Calcifications
In some cases, it is possible to see a residual implant capsule ( Figure 11). The capsule may calcify in the expected prepectoral location (Figure 12).

Silicone Granulomas/Free Silicone
Rupture of a silicone implant with resultant free silicone/silicone granulomas in the breast and the axillary lymph nodes is a well-known complication. Silicone granulomas may present as masses ( Figure 13).

Suspicious Findings
Suspicious findings in patients with a history of BES need to be thoroughly evaluated. Comparison examinations can be helpful. Silicone granulomas may distract the radiologist's attention away from findings suspicious for breast cancer (Figure 14). Silicone granulomas may obscure important findings (Figure 15). Developing masses are suspicious

Suspicious Findings
Suspicious findings in patients with a history of BES need to be thoroughly evaluated. Comparison examinations can be helpful. Silicone granulomas may distract the radiologist's attention away from findings suspicious for breast cancer (Figure 14). Silicone granulomas may obscure important findings ( Figure 15). Developing masses are suspicious and require further evaluation (Figures 16 and 17). were biopsied with a biopsy clip seen in a hematoma in the right prepectoral region on the CC and MLO views. Pathology revealed ductal carcinoma in-situ. An additional biopsy was performed in the right breast for a small focal asymmetry (*) better seen on magnified CC view (b) and pathology demonstrated invasive ductal carcinoma. MRI demonstrates a T1 isointense peripherally enhancing silicone granuloma in the left breast prepectoral region ((c), arrows). In the right breast, a biopsy clip is seen within the biopsy cavity ((d), arrowhead). Anterior and inferior to this region (e), there is a linear non-mass enhancement. More anterior and medial to the non-mass enhancement, there is an enhancing mass (*), corresponding to the biopsy-proven invasive ductal carcinoma. Figure 14. A 65-year-old woman with a history of a ruptured subglandular silicone implant. Screening mammogram (a) demonstrates very dense masses (arrows) in the left prepectoral region on the CC and the MLO views. Suspicious right breast calcifications (arrowhead) were biopsied with a biopsy clip seen in a hematoma in the right prepectoral region on the CC and MLO views. Pathology revealed ductal carcinoma in-situ. An additional biopsy was performed in the right breast for a small focal asymmetry (*) better seen on magnified CC view (b) and pathology demonstrated invasive ductal carcinoma. MRI demonstrates a T1 isointense peripherally enhancing silicone granuloma in the left breast prepectoral region ((c), arrows). In the right breast, a biopsy clip is seen within the biopsy cavity ((d), arrowhead). Anterior and inferior to this region (e), there is a linear non-mass enhancement. More anterior and medial to the non-mass enhancement, there is an enhancing mass (*), corresponding to the biopsy-proven invasive ductal carcinoma.