Pancreatic Neuroendocrine Microadenoma
Definition
- Nonfunctional pancreatic neuroendocrine neoplasm under 0.5 cm
Alternate/Historical Names
- Islet cell tumorlet
- Pancreatic endocrine microadenoma
Diagnostic Criteria
- Circumscribed nodule of neuroendocrine cells <0.5 cm in diameter
- No well formed capsule
- Nonfunctional (no clinical syndrome from secreted polypeptide)
- Cytologically bland
- Mitotic figures very rare
- Staining restricted to 1 or 2 islet polypeptides
- Usually a solitary, incidental finding
- Seen in up to 10% of pancreata
- May be numerous (microadenomatosis) in MEN1 and von Hippel Lindau syndrome
- Rare cases of microadenomatosis outside of these syndromes
- Benign
- No evidence of progression to significant endocrine neoplasm
- Tumors >0.5 cm or functioning should be designated well differentiated neuroendocrine neoplasm
Differential Diagnosis
| Islet Cell Hyperplasia / Aggregation | Pancreatic Neuroendocrine Microadenoma |
|---|---|
| Irregular, non-circumscribed | Circumscribed |
| Usually multiple | Usually solitary |
| Mixture of all four polypeptides | Staining limited to 1 or 2 polypeptides |
| May be associated with chronic pancreatitis | No association with chronic pancreatitis |
| Acinar Cell Nodule of the Pancreas | Pancreatic Neuroendocrine Microadenoma |
|---|---|
| Trypsin, chymotrypsin, lipase positive | Chromogranin, synaptophysin positive |
| Usually basal nuclei | Usually central nuclei |
| Usually apical granular eosinophilic cytoplasm | Usually scant cytoplasm |
Classification / Lists
Pancreatic Endocrine Tumors
- Islet cell hyperplasia / aggregation
- Pancreatic neuroendocrine microadenoma
- Poorly differentiated pancreatic neuroendocrine carcinoma
- Well differentiated pancreatic neuroendocrine (islet cell) tumor
- Mixed acinar-endocrine carcinoma
Bibliography
- Solcia E, Capella C, Kloppel G . Tumors of the Pancreas, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 20, 1997.
- Klimstra DS. Nonductal neoplasms of the pancreas. Mod Pathol. 2007 Feb;20 Suppl 1:S94-112.
- Capelli P, Martignoni G, Pedica F, Falconi M, Antonello D, Malpeli G, Scarpa A. Endocrine neoplasms of the pancreas: pathologic and genetic features. Arch Pathol Lab Med. 2009 Mar;133(3):350-64.
- Périgny M, Hammel P, Corcos O, Larochelle O, Giraud S, Richard S, Sauvanet A, Belghiti J, Ruszniewski P, Bedossa P, Couvelard A. Pancreatic endocrine microadenomatosis in patients with von Hippel-Lindau disease: characterization by VHL/HIF pathway proteins expression. Am J Surg Pathol. 2009 May;33(5):739-48.
Author / Update
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates : 1/9/08, 5/18/08, 5/25/09, 1/1/12
