When a delayed seroma with a low volume is detected more than 1 year after silicone breast implant insertion, aspiration is necessary. However, if the seroma is small and difficult to collect, we may avoid puncturing it, considering the risk of damaging the implant, and the patient may be followed up intensively. Moreover, a delayed seroma is a major symptom of breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL). We encountered a case in which a delayed seroma around a breast implant was punctured to rule out BIA-ALCL after nipple-sparing mastectomy for breast cancer, which led to the diagnosis of locoregional recurrence in the nipple areola. Based on this experience, we suggest that puncture cytology for fluid around breast implants should be performed when a delayed seroma is observed, as it may indicate breast cancer recurrence as well as BIA-ALCL.