Gastrinoma of the pancreas head: diagnostic effectiveness of 111-In-pentetreotide scan.

Different biological effects of somatostatine (STS) and its analogue are mediated by a glycoproteic receptor embedded in the external membrane of normal cells and cells derived from some neoplasms (several neuroendocrine tumors as pituitary tumors, APUD system tumors like gastrinoma, breast cancer, lung cancer etc.). It is possible investigate in vivo distribution of the STS receptors administering a radiolabelled analogue to patients; at present the radioanalogue commercially available is 111-In-DTPA-pentetreotide. Gastrinoma is a functioning tumour, usually smaller than 2 cm, mainly sited in the gastroenteropancreatic tract; 60% of gastrinomas are solitary and malignant; 35% of them are associated with other diseases in MEN 1 syndrome. Recently a 69 year old patient, affected by a painful dyspepsia lasting from 18 years, has been investigated in our department. In the first years of the disease pain was responsive to food ingestion and to anti-H2 drugs; in the last three weeks the patient was treated by omeprazole (20 mg two times in a day) but only partial relief of pain was obtained. The patient was admitted to hospital for acid whitish vomit, usually diarrheic intestinal habitus and epigastric pain. Abdominal CT showed enlarged lymphnodes sited in the iliac area and nearby the gastric great curvature and besides a markedly and inhomogeneously increased thickness of the wole gastric wall. A roentgenogram of the sella turcica, a selective and superselective arteriography of the celiac trunk and its branches were normal. A first endoscopic sonography (ES) showed an hypoechoic area in the head of the pancreas (diameter 1 cm, clear-cut edges), a second sonography performed by the same operator one month after the first showed two hypoechoic areas. Gastrin basal titre was in the upper part of the normal range. In-111-pentetreotide scintigraphy showed an intense uptake of the radiopharmaceutical in the head of the pancreas, after surgery the previous finding was no more evident. Histologic report showed two gastrinomas and resected lymphnodes were metastatic. After surgery no previous symptom was evident and gastrin titre was quite normal. Our data emphasize the sensitivity of ES in the localization of tumours of the pancreas head. ES is less sensitive in the localization of tumours of the body and tail of the pancreas; in this circumstance intraoperative sonography seems to be very sensitive. In-111-pentetreotide scintigraphy is a powerful and not invasive tool to detect with only one investigation pancreatic gastrinoma and its metastatic sites; besides it allows to guess about the efficacy of a treatment with cold octreotide.