14 yr old sister had lymphoma 2 yrs ago and now they see something in pet scan in esophagus. what could it be? please any ideas

See below: You can get physiologic uptake in the esophagus which is normal. It is atypical for lymphoma to recur only in the esophagus. It could periodically be in a lymph node adjacent to the esophagus. I would recommend at least getting an upper endoscopy.

Need more specifics: The esophagus can normally have increased uptake of FDG (be positive on pet). Most commonly is physiologic uptake at the sphincters (start and end of the esophagus), or irritation/inflammation of the esophagus, called benign esophagitis. Esophageal lymphoma is rare. It could be in a lymph node near the esophagus. Ask doctor for more specifics/read the report.