Duodenum (Psammomatous) Somatostatinoma

Definition

Well differentiated duodenal neoplasm composed entirely of somatostatin producing cells, frequently containing psammoma bodies

Nearly all intestinal cases located in or near ampulla of Vater
Uniform cells with bland round regular nuclei
- Few mitotic figures
- Slightly granular, pale eosinophilic cytoplasm
Tubular and glandular architectural pattern usually predominates
- May also have insular and trabecular patterns
Psammoma bodies in glandular spaces in half of cases
Somatostatin stain diffusely positive
- Scattered somatostatin positive cells may be seen in other neuroendocrine neoplasms
- Somatostatin staining may also be seen in poorly differentiated neuroendocrine carcinoma, which is covered separately
Somatostatinoma syndrome seen only in rare patients
- Diabetes mellitus, steatorrhea, cholelithiasis
About half of cases associated with neurofibromatosis type 1
- Pheochromocytoma frequently associated in such cases
- Same behavior as sporadic cases
Rare cases reported associated with MEN1 syndrome
Invades locally and may metastasize
- Duodenal wall, pancreas
- Local node metastases (35%)
- Metastases to liver (10%) and very rarely beyond
In spite of spread, after debulking, we are not aware of any reported cases of disease progression and/or death
Note that about half of somatostatinomas arise instead in the pancreas with a different biology
- Frequently demonstrates somatostatinoma syndrome, metastases and mixed secretory products
- Infrequently associated with neurofibromatosis type 1 or psammoma bodies
- 50% 10 year survival
Rare cases reported elsewhere in and out of GI tract

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 7/27/10, 12/24/11, 3/10/12