Pancreatic neoplasms

There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.

Classification

Classification based on function

• exocrine -  ~ 99% of all primary pancreatic neoplasms
  • pancreatic ductal adenocarcinoma ~ 90-95%
  • cystic neoplasm
  • intraductal papillary mucinous neoplasm (IPMN)
• endocrine -  were previously referred as islet cell tumors because they were thought to have originated from the islets of Langerhans. However, new evidence suggests that these tumors originate from pluripotential stem cells in ductal epithelium ⁶.
  • non-functional
  • functional
• mesenchymal tumours 
  • although the great majority of both benign and malignant pancreatic neoplasms arise from pancreatic epithelial cells, mesenchymal tumors, while rare, can derive from the connective, lymphatic, vascular, and neuronal tissues of the pancreas⁷. 
  • they account for 1-2% of all pancreatic tumors and are classified according to their histologic origin⁷. 
• other
  • metastases to pancreas

Exocrine tumours

• ductal adenocarcinoma is by far the most common primary tumour, usually of the head (65%) and has a very poor prognosis.
• cystic neoplasms are further divided into: (with some overlap)
  • unilocular
    • intraductal papillary mucinous neoplasms(IPMN)
    • serous cystadenoma uncommonly uni/macro locular
  • macrocystic - multilocular
    • mucinous cystic neoplasm : usually body and tail
    • intraductal papillary mucinous neoplasms (IPMN)
    • serous cystadenoma uncommonly uni / macro locular
  • microcystic
    • serous cystadenoma - usually head. 30% have a central scar
  • cystic with a solid component
    • macrocystic tumours can have solid component also
• generally solid
  • solid-pseudopapillary tumour of pancreas

See also - cystic pancreatic mass : differential diagnosis

Endocrine tumours

Endocrine tumours of the pancreas are divided into :

• functional - ~ 85 %
  • insulinoma - most common. 10% are malignant
  • gastrinoma - second most common. 60% malignant
  • glucagonoma - 80% malignant
  • VIPoma - 75% malignant
  • somatostatinoma - 75% malignant
• non-functional  -  ~ 15% :
  • third most common
  • 85-100% malignant
  • usually larger

Mesenchymal tumours

Account for 1-2% of all pancreatic tumors and are classified according to their histologic origin⁷:

• lymphangioma
• lipoma
• pancreatoblastoma
• teratoma
• lymphoma
• schwannoma
• neurofibroma
• sarcoma

Classification based on location 

Head

• serous cystadenoma
• intraductal papillary mucinous neoplasms (IPMN)
• ductal adenocarcinoma
• pancreatoblastoma (rare and in children)

Body and tail

• mucinous cystic neoplasms
• papillary cystic neoplasm of the pancreas