Purpose To describe a case of peripapillary pachychoroid syndrome (PPS) in a diabetic patient with cystoid macular edema (CME), treated with intravitreal dexamethasone implant (IDI) injection. This report also illustrates the history of the disease after repeated IDI and dexamethasone topical treatment. Methods A case report. Results A 77-year old male patient with PPS and good diabetic control was treated with dexamethasone implant for CME. After an initial morphofunctional improvement associated with a first IDI, the disease relapsed after the second dexamethasone implant injection. This was associated with a significant increase in both intraretinal fluid and choroidal thickness, with subsequent visual acuity (VA) decrease. At this point, a topical dexamethasone treatment was performed and, despite a morphological improvement, VA worsened compared with baseline, likely because of anatomical damage. Conclusion In this report, the importance of the recognition of PPS is underlined and the possible occurrence of a “rebound” effect due to repeated IDI is described.