Primary Hepatic Gastrinoma Causing Zollinger-Ellison Syndrome: A Rare and Challenging Diagnosis

The majority of gastrinomas causing Zollinger-Ellison syndrome (ZES) are located in the duodenum or the pancreas. Primary hepatic gastrinomas (PHG) are extremely rare and difficult to diagnose because the liver is the commonest site of metastatic disease and gastrinomas can be very small. Furthermore, gastrinomas are typically slow-growing thus a missed, occult primary tumour may not become evident for many years. The diagnosis of PHG is therefore dependent on a careful search for a primary and long-term biochemical follow-up following curative hepatic resection. We report a case of a 7 cm PHG in a 48 year old man with ZES. Preoperatively, both a basal and stimulated gastrin levels were elevated. Surgical exploration including intraoperative ultrasound and duodenotomy, failed to reveal a primary. Patient underwent a right hepatectomy. Yearly, gastrin and secretin stimulation tests remain normal 6 years following surgery. He remains symptom free off all medication. An additional 26 cases of PHG were found. Including this case, 21 had at least 1 year follow-up, however only eight had greater than 5 years (median 24 months). Post-op gastrin levels were reported in 25, however provocative testing was done in only 10. Persistence and recurrence occurred in one and four, respectively. PHG causing ZES is extremely rare. Although the current literature claims to include 26 additional cases of PHG, without a thorough search for the primary and long-term follow-up data including provocative testing, this diagnosis remains a challenge.