Macrocystic serous cystadenoma of the pancreas
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There is a large (~5 x 5 cm) well-circumscribed, homogeneous lesion in the tail of the pancreas adjacent to the spleen and left kidney. It has a clear margin and shows fluid attenuation, suggestive of a cystic lesion. The pancreas is otherwise unremarkable.
Following administration of contrast there is no convincing solid component to the mass. No calcifications.
Distal pancreatectomy and splenectomy
A distal pancreatectomy specimen comprising pancreas 80x40x20 mm with perpancreatic fat up to 170,, and spleen weighing 250 gram. Arising form the posterior pancreatic surface is a disrupted unilocular cystic mass 50x35x15 mm from the pancreatic margin. The internal lining is smooth. Cyst contents are clear and not mucoid. The cyst does not communicate with pancreatic duct.
Sections show a unilocular cyst surrounded by normal pancreatic parenchyma. The cyst is lined by a single layer of bland low cuboidal cells supported by dense, hyalinised fibrous connective tissue. Some of the cuboidal cells have clear cytoplasm. Special stain demonstrate the presence of glycogen within the cyst lining cells. No features of mucinous epithelial differentiation are recognised (absence of columnar cytology, mucin vacuoles). By immunohistochemistry, the cyst lining cells are positive for epithelial markers CAM 5.2 and AE1/3. There is no staining for neuroendocrine or vascular markers. No ovarian type stroma is identified in H&E sections or immunohistochemistry for oestorgen and progesterone receptors. The peripancreatic lymph nodes have reactive features. The spleen is histologically normal.
An immunohistochemical stain for CEA reveal no staining in the epithelial lining of the cyst. This support non-mucinous differentiation of the epithelium.
Benign pancreatic cyst, favour macrocystic serous cystadenoma
In an adult female, the differential for a cystic lesion in the pancreatic body and tail includes
- mucinous cystadenoma
- intraductal papillary mucinous tumour (IPMN)
In this situation, the imaging appearance of the cystic lesion and the patient's age is typical for a mucinous cystadenoma of the pancreas, but on pathologic analysis, an oligocystic/macrocystic cystadenoma was diagnosed.