Substernal colon interposition is a good reconstruction option after salvage surgery for caustic ingestion injury. Although redundancy and reflux sometimes complicate these cases, there have been no reports in the English literature of perforated diverticula in interposed colon segments. We report a 23-year-old man who underwent substernal colon flap reconstruction after caustic ingestion injury. He had perforated colon diverticulitis develop, which led to a lung abscess 7 years later, followed by resection of the necrotic lung parenchyma and colon repair. This rare case illuminates the importance of including perforated diverticula in interposed colon in the differential diagnosis for such patients.