Spontaneous drainage of a large cystic tumor

A case is described of a 58 year old male who presented with a large mass on the left side of the abdomen which was found to be cystic by ultrasound. A presumptive diagnosis of pancreatic pseudocyst was made. Shortly thereafter, the mass drained spontaneously further suggesting this diagnosis. At surgery a month later, however, the mass was found to be a metastic leiomyosarcoma with cystic degeneration that had eroded into the gastric wall. This case serves to illustrate that cystic abdominal masses, even ones that drain spontaneously into the gastrointestinal tract, may not be pancreatic pseudocysts.