False-positive diagnoses of damaged breast implants on imaging: a report of two cases.

Background: Silicone breast implants (SBIs), used in breast reconstruction, are durable and resistant to breakage and internal gel leakage. However, regular imaging examinations are crucial, as symptoms may not be apparent even if the implant ruptures. There are several known imaging findings that suggest SBI failure. Although artifacts such as moisture and air bubbles or substances similar to the gel extending outside the shell may appear on imaging, no reports have demonstrated false-positive diagnoses of damaged SBIs in detail. Hence, we present two cases in which failure was suspected based on the imaging results but not confirmed. Case Description: In case 1, at the 4-year follow-up after implant-based breast reconstruction, ultrasonography revealed a stepladder sign, and magnetic resonance imaging (MRI) revealed the salad oil sign. Although SBI failure was suggested, intraoperative examination revealed only a small amount of fluid retention within the capsule and no SBI fractures. Consequently, the imaging results were proved to be artifacts. In case 2, at the 7-year follow-up after implant-based breast reconstruction, ultrasonography revealed a subcapsular line sign, and MRI confirmed a keyhole sign. Although SBI failure was suggested, intraoperative examination revealed no implant fractures. Hematogenous serous effusion was found within the capsule, and blood clots and a large amount of fibrinous mass were found deposited at the bottom of the capsule. These findings caused false-positive diagnoses on imaging. Conclusions: In cases of suspected fractures, patients may opt for either observation or surgical removal, or replacement of the implant. When choosing the latter, it is important to inform patients of the possibility of an unbroken implant.