A 48-year-old, previously healthy woman presented with an asymmetric, painless swelling of her left breast three years after cosmetic bilateral breast augmentation (McGhan, 275 gram). Blood laboratory measurements and cytological puncture showed no abnormalities. Both prostheses were removed and replaced (Sebbin, 330 gram). Six months after replacement swelling of her left breast reoccurred. MRI showed a fluid collection and intact prostheses (figure 1). Both implants were removed together with their capsules. Histology of the capsule of the left breast showed sheets of large pleomorphic cells with polymorphic nuclei at the border of seroma and capsule without infiltration of the capsule (figure 2).