Breast augmentation surgery is the most common cosmetic surgical procedure, consist of 15.8% of all cosmetic procedures (1). And the number of procedure is consistently increasing in Asian countries including South Korea. The major age group of breast augmentation is reported between 35 and 40 years. Pregnancy and lactation-associated changes frequently occur within augmented breasts (1). Several studies reported the complications and its imaging features associated with implants (2, 3, 4). And recently, 779 cases of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) has been reported worldwide. Common imaging feature of BIA-ALCL is peri-implant effusion over 1 year after implant insertion (3). Although most of lesions in lactating or augmented breast are reported as benign diseases, malignancy associated with pregnancy or implant should be considered (3, 5). Postpartum breast periimplant galactocele is rare disease entity as only one case has been reported (6). We report the case of peri-implant galactocele in lactating women after using breast pump.

A 34-year-old, 1 month-postpartum female visited our institution with a complaint of left breast enlargement. She was using breast pump for 1 month. She had both retromammary breast augmentations for 7 years.

US of left breast revealed large amount of hyperechoic peri-implant fluid collection, more than 8 cm in depth (Fig. 1A). US of both breasts showed hyperechoic fibroglandular tissue proliferation and ductal dilatations which is physiologic pregnancy associated change (Fig. 1B). US of right breast revealed intact implant in the retromammary space, superficial to the pectoralis major muscle. US-guided fine needle aspiration (FNA) was done by 21G-needle and 40 cc of milk component was drained (Fig. 1C, D). In the FNA cytology, there were numerous semitransparent variable sized crystals which is rare but suggestive finding for galactocele (Fig. 1E). The patient did not return to our institution for additional follow-up.

Fig. 1
Imaging and pathologic features of peri-implant galactocele in postpartum female.
A. Left breast US reveals hyperechoic peri-implant fluid collection (arrow).

B. Left breast US reveals hyperechoic fibroglandular tissue proliferation and ductal dilatation.

C. US-guided FNA is done using a 21G-needle.

D. Approximately 40 mL of milk component is drained.

E. In FNA cytology (Papanicolaou stain, × 400), numerous semitransparent crystals are observed. FNA = fine needle aspiration

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This study was approved by the Institutional Review Board of our institution and the requirement for informed consent was waived (IRB No. 2021-03-002).

Galactocele is the most common benign breast lesion in women who are lactating or recently stopped lactation. Galactocele is a milk-containing retention cyst in the lactiferous duct, originated from ductal obstruction (5, 7). The imaging features of galactocele vary depending on variable amounts of fat, protein, and water contents in the cyst. On US, it manifests as simple or complicated cyst with variable internal echogenicity (5, 8). In this case, galactocele occurred in retromammary, peri-implant area which is unusual location for galactocele. We assumed that negative pressure to the retromammary fat area caused by breast pump, resulted in a dead space and eventually a milk fistula formed between dead space and peri-implant area. If implants were located in the retropectoral area, peri-implant galactocele might not be occurred.

Peri-implant fluid collection is mostly caused by benign causes, such as infection, seroma, spontaneous or traumatic hematoma, implant rupture and idiopathic causes, but can also be caused by malignancies (9). Rare but important differential diagnosis of this case is BIA-ALCL. BIA-ALCL was recently recognized by World Health Organization as a unique T-cell anaplastic lymphoma kinase (ALK)-negative ALCL. It has been reported that BIA-ALCL originated from chronic inflammation or activation of T cells to bacterial biofilm of breast implant (3). It manifests as rapid swelling of breast due to late-onset (> 1 year after implant insertion) periprosthetic effusion (85%) or as a mass (median of 10 years after implant insertion, 15%) (3). BIA-ALCL usually manifests as homogeneous peri-implant effusion with or without inflammatory changes of adjacent breast tissue and irregular capsule contour on US. Cytopathologic analysis including immunophenotyping for CD30, CD2, CD3, CD4, CD5, CD7, CD8, and CD45 markers and ALK receptor expression should be done for diagnosis of BIA-ALCL (3). Positive results on CD30 marker and negative results for ALK receptor are known to be a fundamental diagnostic tool for BIA-ALCL (10). Not only cytologic results but also clinicopathologic correlation with clinical information is essential factor for correct diagnosis of BIA-ALCL (3). Our case showed similar radiologic and clinical features to BIA-ALCL which was late-onset (7 years after implant insertion) peri-implant effusion. However, clinical information such as postpartum status with feeding breast and milk component with galactocele-specific crystals on FNA was considered as more suggestive factor for galactocele. As these factors strongly suggested the diagnosis for galactocele whether than other malignant lesions including BIA-ALCL, additional marker analysis including CD30 was not done in our case. According to National Comprehensive Cancer Network guideline for diagnosis of BIA-ALCL, more than 50 mL of fluid should be collected (10). In our case 40 mL of milk component was collected and more fluid was not able to be collected.

We reported the case of peri-implant galactocele in lactating women after using breast pump. Various diseases, especially BIA-ALCL can cause the peri-implant fluid collection in augmented breast. Correlation imaging features with clinical information and cytologic analysis plays an important role in appropriate management.