Platynosomum fastosum is a small fluke found in the biliary ducts and gallbladder of cats. Its lifecycle includes the snail Sublima octona as intermediate host, and lizards, toads and geckos as paratenic hosts. Affected cats are usually adult and acquire the parasite by feeding on infected lizards. This parasite occurs across the world but is more frequent in tropical areas. The clinical signs range from none to obstruction of the biliary tract, with hepatic failure and death, reinforcing the necessity of including the liver fluke Platynosomum fastosum in the differential diagnosis of hepatic diseases in cats. This report describes an unusual case of a cat with a polycystic hepatic disease and a severe infestation by Platynosomum fastosum and presents a review of the literature.