The pancreas is the site of several potential pathologies and the decision on whether or not to perform pancreatectomy is dependent upon on the lesion’s etiology and malignant potential. Solid lesions are the most straightforward because any solid tumor of the pancreas can be assumed to be malignant (or carry malignant potential) and should be resected if feasible. The two most common solid lesions of the pancreas are pancreatic adenocarcinoma and the pancreatic endocrine tumors. The evaluation of cystic lesions is more complex, since some can be treated with observation alone, but others have malignant potential and should be resected. Each of these etiologies is described in further detail below.

Pancreatic adenocarcinoma is the most common solid lesion of the pancreas. This cancer is known for its poor prognosis, which stems from the fact that the tumor is not usually diagnosed until advanced stages, and that current chemotherapeutic regimens are largely ineffective. When a pancreatic adenocarcinoma arises in the body or tail of the pancreas, the lesion has room to grow locally without impinging on nearby structures. Patients do not typically develop symptoms until the tumor has extended posteriorly and invaded the celiac plexus of nerves, which causes back pain. By this point, most patients have already developed liver metastases and are no longer candidates for pancreatic resection. By contrast, a lesion that arises in the head of the pancreas will tend to present at an earlier stage because the tumor will obstruct the common bile duct, producing jaundice at an earlier stage.

In the absence of metastases, resectability of a pancreatic cancer is determined by whether or not the tumor involves the major blood vessels that course through the region. The superior mesenteric artery, superior mesenteric vein, and celiac trunk must all be patent and free of tumoral invasion. Certain tumors that involve only a short segment of the superior mesenteric vein can still be resected along with a vein resection. In borderline resectable cases, neoadjuvant chemotherapy can be considered, with the hopes of producing tumor shrinkage. Ultimately, even among the minority who are surgical candidates, most patients will be found to have nodal metastases upon resection, which portends a poor prognosis.

Pancreatic endocrine tumors comprise a group of tumors that are characterized by classic symptoms sets that result from hormone production. For example, insulinoma is a tumor that—as the name suggests—produces insulin. The high levels of circulating insulin cause what is known as Whipple’s triad: a patient has episodes of confusion and altered mental status, corresponding with documented hypoglycemia, and these symptoms are relieved upon administration of glucose. Gastrinomas, with their high circulating levels of gastrin, produce fulminant peptic ulcer disease, known as Zollinger-Ellison syndrome. Other, more rare endocrine tumors of the pancreas include VIPoma, somatostatinoma, and glucagonoma—each with their own classic symptoms. Nonfunctioning tumors are actually the most common type of endocrine tumors. These tumors are clinically silent, and are thus either found incidentally, or are discovered when the tumor’s mass effect ultimately causes symptoms (Fig. 9.1). Unlike pancreatic adenocarcinomas, endocrine tumors of the pancreas are less aggressive and patients have significantly longer survival—even with metastatic disease.

The differential diagnosis of pancreatic cysts includes the pseudocyst, serous cystic neoplasm, mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm. The management of cystic lesions is more nuanced than solid lesions, because some are clearly benign, while others harbor malignant potential. Pseudocysts are the remnants of an attack of pancreatitis, and are never premalignant. These lesions usually resolve with time, although surgical intervention can be required if they persist or cause symptoms such as gastric compression. A serous cystic neoplasm is also a benign lesion that only rarely requires an operation. By contrast, both mucinous cystic neoplasms (MCN) and intraductal papillary mucinous neoplasms (IPMN) harbor malignant potential and should be resected, although centers differ in their specific criteria for intervention. The diagnosis of an MCN or IPMN is made by a combination of typical imaging characteristics and analysis of the cyst fluid obtained by endoscopic ultrasound guided aspiration.

Another indication for pancreatic surgery can be the sequela of chronic pancreatitis. The repeated bouts of inflammation can lead to scarring and strictures of the pancreatic duct. Over time, this leads to obstruction of the duct, causing postprandial pain and weight loss. In addition, the pancreatic atrophy and calcifications seen in chronic pancreatitis can obscure imaging, and make it difficult to rule out a malignant stricture. As a result, resection of the head of the pancreas is sometimes indicated.

Finally, tumors of the duodenum often require pancreatectomy due to the anatomical attachments between the duodenal sweep and the head of the pancreas. Duodenal tumors that lie in close proximity to the ampulla usually require a Whipple procedure for resection. In these cases, the pancreatectomy is just the means for performing a duodenectomy.