This document summarizes different cystic and neoplastic lesions of the pancreas. It describes non-neoplastic lesions such as pseudocysts, lymphoepithelial cysts, duct retention cysts, and mucinous cysts. It also describes several neoplastic lesions - serous cystic neoplasms, mucinous cystic neoplasms, intraductal papillary mucinous neoplasms, intraductal tubulopapillary neoplasms, and solid pseudopapillary neoplasms. For each type of lesion, it provides brief details on pathogenesis, histopathological features, immunochemical markers, and genetic mutations when relevant.

1. NON NEOPLASTIC
LESSIONS
Pseudocyst
Lymphoepithelial
cyst
Duct retention
cyst
Non neoplastic
mucinous cyst
Paraampullary duodenal wall
cyst – Groove Pancreatitis
NEOPLASTIC
LESSIONS
Serous cystic
neoplasm
Mucinous cystic
neoplasm
Intraductal papillary
mucinous neoplasm
Intraductal
tubulopapillary
neoplasm
Solid pseudopapillary
neoplasm
Cystic acinar
neoplasm
Cystic pancreatic
neuroendocrine tumors
CYSTIC LESSIONS OF PANCREAS
CONGENITAL CYSTS:
Unilocular, thin-walled cyst lined by uniform cuboidal or
flattened epithelium filled with clear serous fluid.
EG:-Autosomal-dominant Polycystic Kidney Disease
PSEUDOCYST:
75% of all pancreatic cysts.
Lack an epithelial lining.
Arise following acute pancreatitis
Resolve spontaneously.
LYMPHOEPITHELIAL CYST:
Lined by squamous / flat / cuboidal / transitional epithelium
with abundant lymphocytes.
DUCTAL RETENTION CYST / SIMPLE CYST:
Caused by obstruction.
Unilocular cyst lined by a layer of simple epithelium.
MUCINOUS NON NEOPLASTIC CYST :
Simple cyst lined by mucinous epithelium.
PARAAMPULLARY DUODENAL WALL CYST/ GROOVE
PANCREATITIS:
Caused by obstruction of the minor papilla.
Microscopically, it consists of dilated ductal structures within the
duodenal wall
SEROUS CYSTIC NEOPLASMS :
M/C - tail of the pancreas.
Grossly, the tumor has a spongy appearance with a stellate central scar with
cysts that are filled with serous fluid.
Lined by glycogen-rich cuboidal cells.
IHC - The lining cells are positive for cytokeratin, inhibin, calponin and
MUC6
M/C genetic abnormality - inactivation of the VHL gene on chromosome 3p.
MUCINOUS CYSTIC NEOPLASMS:
The cysts do not communicate with the ductal system.
These cysts are lined by columnar mucin-producing epithelium.
Dense ovarian stroma present with high levels of CEA.
IHC - EMA, SOX9 and cytokeratins 7, 8, 18 and 19, CK10 and CK20 are
positive.
50% of patients with invasive adenocarcinoma arising in a MCN harbor
KRAS, TP53 and SMAD4 mutation.
INTRADUCTAL PAPILLARY MUCINOUS NEOPLASMS:
Involve larger ducts of the pancreas.
M > F.
20% are multifocal.
Absence of the dense “ovarian” like stroma.
Involvement of a pancreatic duct.
Mutations harboured are :- KRAS, RNF43, TP53, SMAD4, GNAS.
Mucinous
epithelial type
MUC1 MUC 2 MUC6
Gastric + / variable - + / variable
Intestinal - + -
Pancreatobiliary + - +
Oncocytic - / variable - +
INTRADUCTAL TUBULOPAPILLARY NEOPLASM:
Solid nodular tumor obstructing the duct system.
Do not harbor KRAS or BRAF mutations.
Expression of DPC4 is retained in most cases.
SOLID-PSEUDOPAPILLARY NEOPLASM:
Common in young women.
Well-circumscribed neoplasms having solid and
cystic components. Beta catenin mutation is seen.