Pancreatic Lesions Part 2

Part 2 of my review of pancreatic lesions for radiology board exams. Download the free study guide on this topic here.

Show Notes/Study Guide:

True or false: Pancreatic pseudocysts can be located within the mediastinum?

True.  Pancreatic pseudocysts, if large and appropriately positioned, can extend through the diaphragmatic hiatus into the mediastinum.

What are key features of serous cystic tumors of the pancreas?

First, serous cystic tumors of the pancreas are benign.  The most common are the microcystic pancreatic serous adenomas and the less common are the serous macrocystic adenomas.  Microcystic means something like you have greater than 6 cysts that are all smaller than 2 cm in size.  These are highly vascular though benign tumors that are most commonly seen in elderly females. These are benign so surgery should be avoided.  MRI is often most helpful for definitive diagnosis.  A central stellate scar and a lobulated contour are characteristic for these lesions.

If you see multifocal serous pancreatic tumors what syndrome should you first consider?

Von Hippel Lindau.  Also, if you simply see a true pancreatic cyst VHL should come to mind.

What are key features of a mucinous cystic neoplasm of the pancreas?

First, these are premalignant and are not always benign unlike the serous cystic tumors.  Mucinous cystic tumors are surgical lesions.  These often have fewer and larger cystic components compared to the serous cystic tumors.  Serous cystic tumors are most common in elderly females and mucinous cystic neoplasms are most common in perimenopausal aged females.  A key imaging feature is a fibrous capsule and these are round/oval and not lobulated.  Mucinous cystic neoplasms have an association with elevated CEA levels.

True or false: Solid pseudopapillary neoplasms (SPN) aka solid and papillary epithelial neoplasms (SPEN) are most common in middle aged females?

False.  SPN/SPEN are most common in young females to include teenagers.

What are classic imaging findings for SPN/SPEN?

SPN/SPEN are classically encapsulated, solid masses with hemorrhage from internal autoinfarction.  Classic features for diagnosis are encapsulated pancreatic solid masses with internal hemorrhage in a young female.

What is the prognosis of metastatic SPN/SPEN?

The prognosis is often good, even if metastatic.  These tumors should be resected as they are most often benign but have low-grade malignant and metastatic potential.

What pancreatic tumors have a capsule?

Serous pancreatic tumors and IPMNs are not encapsulated.  Tumors of the pancreas that are encapsulated are mucinous, solid pseudopapillary neoplasms, and so called sugar tumors. The best imaging study to evaluate for a capsule is MRI. If you see a macrocystic pancreatic tumor and it has no capsule think of a macrocystic serous tumor; if there is a capsule think macrocystic mucinous tumor.

What is the cystic pancreatic lesion that is more common in males?

IPMNs are the only pancreatic cystic lesion that is more common in males.  This is the most common mucin secreting tumor and is the only intraductal mucin secreting tumor.  Because this is intraductal there is an association with elevated amylase levels and a high CEA.  These may be multifocal (other pancreatic cystic lesions are often not multifocal) and these are classically non-septated lesions.  These can be sub-classified by location as main duct or side-branch IPMNs. 

True or false: Side-branch IPMNs are classically associated with chronic pancreatitis.

False. There is an association between chronic pancreatitis and main duct IPMNs.

What pancreatic tumor is nicknamed the “daughter” lesion?  What about “mother”, “grandma” and “grandfather”?

Daughter lesion: SPN/SPEN (teenage girls)

Mother: Mucinous tumors

Grandma: serous tumors

Grandfather: IPMNs

What is the most common solid tumor of the pancreas?

Pancreatic adenocarcinoma

What is the most common location for pancreatic adenocarcinoma?

Pancreatic head.  Therefore, look for abrupt pancreatic duct obstruction and vascular invasion surrounding the pancreatic head.  Unfortunately, pancreatic adenocarcinoma has a high rate of vascular invasion and is unresectable at presentation in the majority of cases.  Resectability usually requires no metastatic disease, minimal to no encasement of the celiac, superior mesenteric, and hepatic arteries and no contact with the superior mesenteric vein and portal vein, or contact that is mild enough that these can be surgically reconstructed.  

 What is the most common location for pancreatic neuroendocrine tumors?

The pancreatic body and tail are the most common sites for neuroendocrine tumors as these are where islet cells are present.

What are some of the most common pancreatic neuroendocrine tumors?

The most common pancreatic tumors in no specific order include insulinoma, gastrinoma, somatostatinoma, VIPoma and glucagonoma. These also have syndromic associations.  On imaging for pancreatic neuroendocrine tumors look for circumscribed, solid masses that are encapsulated.  Remember the potential role for somatostatin-receptor imaging with Gallium 68 dotate PET/CT.

A few key features to remember for board exams:

Gastrinoma in the pancreas should make you consider MEN1.  Also, remember association between gastrinoma and peptic ulcer disease (Zollinger Ellison Syndrome) with a MEN1 association.

All neuroendocrine tumors have hormone secretion and when hyperfunctioning can cause characteristic clinical symptoms.

VIPoma secrete vasoactive intestinal peptides (VIPs) and result in severe watery diarrhea, hypokalemia and achlorhydria.

If you see a pancreatic mass in a young male of Asian descent, what is the top differential consideration for board exams?

A pancreaticoblastoma is classic in this setting.  Look for associated elevated AFP levels.  Classic imaging features are that of a circumscribed large pancreatic head lesion with internal necrosis and blood products.

True or false: Accessory splenic tissue can be located in the pancreas?

True.  When present in the pancreas, accessory splenic tissue can look like a solid, encapsulated pancreatic mass.  Key is to look for signal/appearance identical to spleen on multiphase CT or MRI and, if necessary, consider a nuclear medicine tagged RBC or sulfur colloid scan for confirmation.