Pancreatic Incidentalomas

All asymptomatic pancreatic lesions, discovered incidentally by imaging for an unrelated indication can be considered pancreatic incidentalomas (PI).

PI are discovered with increasing frequency as the use of high quality cross sectional imaging is becoming more widespread.

These lesions cover a wide spectrum of pathology from benign simple cysts through potentially malignant lesions such as intraductal papillary mucinous neoplasia, to frankly malignant adenocarcinoma.

The incidence of malignancy in PI is lower than in symptomatic pancreatic lesions (31% vs. 76%), however, malignant histology is found up to 30% and pre-malignant up to 50% in PI in surgical series (there can be a selection bias).

A solid lesion of the pancreas must be considered malignant or potentially malignant until proven.

Role of Imaging is to discriminate the malignant potential of PI, thus suggesting the best treatment option.

A simple classification of PI subdivides lesions in SOLID LESIONS (NON ENHANCING or ISOENHANCING; HYPOENHANCING; HYPERENHANCING) and CYSTIC LESIONS (NON COMUNICATING or COMUNICATING with main pancreatic duct).

Fatty infiltration, pancreatic lipoma, intrapancreatic spleen, pancreatic anomalies can give a solid appearance of the pancreas.

However, all different solid tumors of the pancreas can be incidentally discovered.

Among CYSTIC LESIONS of the pancreas, frequency of detection of CPL ranges from 2.4% to 19.6%. Corrected for underreporting and excluding Pts with previous Hx of pancreatic disease, prevalence ranges from 7.5% to 13.5%. The prevalence increases with age: from 7.9% below 70 yo to 40.2% over 70 yo. Also size and number of CPL for patient increase with age.

Pseudocysts are usually present in Pts with previous Hx of pancreatitic. Cystic tumors of the pancreas can be subdivided according to the presence or not of a communication of the cystic lesions with the main pancreatic duct.

Serous cystic neoplasm (SCN), mucinous cystic neoplasm (MCN), solid pseudopapillary tumor (SPT) can all have cystic appearance, the latter being more frequent in young patients: MCNs occur almost exclusively in the body-tail of the gland, whereas SCNs have no site predilection; cystic lesions in males and those in the head of the pancreas are unlikely to be MCN.

A multicystic pattern of pancreatic lesions is more frequently observed in SCN, whereas an oligo- and/or macrocystic pattern is more frequently observed in MCN.

Serous oligocystic adenoma has a multicystic or lobulated contour with or without septation, whereas mucinous cystadenoma has a smooth contour with or without septation.

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Lernziele:

Finally IPMN are cystic lesions communicating with main pancreatic duct, whose malignant potential is related to the involvement of the main pancreatic duct, size of the cyst and presence of solid component inside the lesions.

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