Unilateral Breast Inflation Caused by Breastfeeding after Polyacrylamide Hydrogel Injection.

Polyacrylamide hydrogel (PAAG) has been widely used in Russia and China as an injection material for cosmetic surgery. We report the case of a 36-year-old woman who noted breast enlargement subsequent to breastfeeding, after a PAAG injection. In 2016, a PAAG injection was administered to her under both mammary glands at a nearby cosmetic surgery clinic for breast augmentation. After she started breastfeeding following delivery in 2020, she was admitted to our hospital because of a rapid left breast enlargement and unbearable pain. Contrast-enhanced chest computed tomography revealed marked fluid retention in the left breast, and the mammary gland tissue had been pushed outward. A skin incision revealed a significant amount of yellowish-white odorless fluid accumulation. On surgery, a foreign body remained around the pectoralis major muscle, but complete removal was impossible. Currently, 3 months have passed since the operation; however, the patient has not experienced any further pain. There have been many reports on complications caused by PAAG injection. In our case, commencing breast feeding after receiving PAAG injections resulted in a rapid unilateral breast enlargement, and there is no similar report from Japan. In this case, suppressing lactation and rapid removal of the foreign body is the most important measure. It is difficult to completely remove PAAG once it has been injected. PAAG injections for breast augmentation should be avoided in all patients.