Background: Breast implant-associated anaplastic large cell lymphoma (ALCL) is commonly associated with diagnostic delay due to the insidious nature of presentation with late periprosthetic fluid collection, mass or locoregional adenopathy. Case Presentation: A 75-year-old woman with a remote history of right breast cancer treated with modified radical mastectomy and immediate reconstruction with a double-lumen silicone implant presented 13 years later with volume asymmetry. The implant was removed and a saline implant was placed. Five years later, she presented with acute onset of right breast enlargement and pain. Ultrasound revealed an associated periprosthetic fluid accumulation. Cytology showed anaplastic lymphoma kinasenegative, CD30-positive ALCL without associated systemic disease. The patient was treated with implant removal and total capsulectomy. Conclusion: Due to the insidious presentation of ALCL, a high index of clinical suspicion must be maintained when evaluating patients for delayed presentation of volumetric discrepancy. Treatment typically entails implant removal. Indications for additional systemic treatment include extracapsular spread of ALCL or presence of a periprosthetic tumour.