Intraductal papillary mucinous cancer (IPMN) is a cancer of the pancreas that is associated with growth within the pancreatic duct and production of mucin. Intraductal papillary mucinous cancer can sometimes present as a cyst or mucinous cystic neoplasm (MCN). Diagnostic criteria have been published to help surgeons know which patients need surgery. These criteria usually involve anatomic identification based on imaging cyst, size of the cyst, the presence of a nodule, architectural changes, obstruction of the main duct, and presence of pain, jaundice, or any other symptoms.
The risk of IPMN is unknown. Smoking is an identified risk factor for pancreatic cancer.
The true incidence of intraductal papillary mucinous cancer is unknown as most IPMNs are small and asymptomatic. It is estimated that approximately 2.6% of adults in the United States have intraductal papillary mucinous cancer.
Like most cancers, IPMN is thought to progress from a benign neoplasm to malignancy through DNA damage/mutation. The damaged DNA lose protective factors and undergo malignant degeneration leading to uncontrolled growth and convalescence. IMPN can be classified into main or branch duct type. Sometimes IPMN can have the consistency of both main and branch duct types. In all cases of main branch duct type involvement, surgical resection is recommended. Branch duct type cases may be observed. Branch duct type IPMNs are generally believed to carry less risk of malignancy compared to main duct system IPMN.
Other tests like cytology may be helpful in the diagnosis of intraductal papillary mucinous cancer. Cytology is helpful if the cytopathologist sees cells with dysplasia or malignant appearing changes.
Histologically, IPMNs are classified as intestinal type, pancreaticobiliary type, oncocytic type, and gastric type. Cancers are characterized as (1) tubular type, in other words, morphologically indistinguishable from ductal adenocarcinoma) or (2) colloid type, or in other words, morphologically similar to other exocrine organ cancer, for example, the breast and skin. Colloid carcinomas have a better prognosis than tubular carcinomas.
Intraductal papillary mucinous neoplasms can come to clinical attention in a variety of different ways. The most common symptoms include abdominal pain, nausea, and vomiting. The most common signs patients have when they come to medical attention include jaundice (yellowing of the skin and eyes caused by obstruction of the bile duct), weight loss, and acute pancreatitis.
Initially, patients may undergo an abdominal ultrasound evaluation. CT scan of the abdomen or MRI of the abdomen with contrast is used to identify IPMN definitively, however. Also, endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic ultrasound can be used to diagnose IPMN by obtaining a biopsy. A laboratory panel is needed to identify a presence of jaundice through bilirubin levels. Also, amylase and lipase levels are helpful to delineate the diagnosis of acute or chronic pancreatitis associated with IPMN.
Only surgery can be done to treat patients with IPMN of the pancreas with high-grade dysplasia or IPMNs that have progressed to invasive carcinoma. Surgery is recommended for all mucinous neoplasms and main duct neoplasms. In cases of branch duct neoplasm cysts, observation may be elected. For patients with invasive ductal adenocarcinoma of the pancreas, postresection adjuvant therapy improves survival, even in patients with positive margins or involved lymph nodes. There is controversy as to the best adjuvant strategy. Due to the significant morbidity and mortality associated with pancreaticoduodenectomy or distal pancreatectomy, the patient's and surgeon's decision to perform surgery should include factors such as the patient's age and general health, the malignant risk of the lesion, and the suspicion for malignancy. Cysts not meeting criteria for resection are typically followed with surveillance imaging.
If the main duct is greater than or equal to 1.5 cm, suitable patients should undergo surgical resection. If the whole duct is affected, then total pancreatectomy is the treatment of choice. If the head of the pancreas is affected, then Whipple is the operation of choice. If the tail of the pancreas is affected, then distal pancreatectomy plus or minus splenectomy may be warranted.
Differentials include mucinous cyst, pancreatic pseudocyst, serous cyst. There are 3 types of Intraductal papillary mucinous tumors: main duct, branch duct, and mixed and branch duct type IMPN.
For operative technique, an upper midline incision is made, once, inside the abdomen, entrance to lesser sac is created with harmonic scalpel. Kocherization of the duodenum performed. Once pancreas identified, the tissue is dissected where IPMN of the pancreas is involved. As much as possible, the pancreas parenchyma should be preserved to ameliorate the side effect of diabetes mellitus secondary to missing pancreas tissue. One trick for intraoperative surgery is to palpate the duct of the pancreas. If feels dilated, has to be resected as it needs to be assumed that it is dilated due to increased mucin production (abnormal), therefore has to be resected. Confirm negative margins with a frozen section by sending to pathology.
There is no role for radiation treatment in intraductal papillary mucinous neoplasm.
Chemotherapy may be indicated if intraductal papillary mucinous neoplasm is considered unresectable.
Staging needs to be completed with computed tomography (CT) of the chest, abdomen, and pelvis with intravenous contrast.
The 5-year survival for intraductal papillary mucinous neoplasm is about 45% to 50%. Much better than pancreatic adenocarcinoma 5-year survival of 30%.
After surgery, complications such as bleeding, anastomotic leak, abscess, or death can occur. Pancreatic enterocutaneous fistulas are a dreaded complication of pancreatic surgery for which to be aware. Typically, these are treated with total parenteral nutrition (TPN), nothing by mouth, and drainage and possibly somatostatin analogues.
Early ambulation is recommended postoperatively. Drain placed at surgery should be removed after patient tolerates a regular diet without increase of drain output. If suspect for pancreatic fistula, send fluid for amylase, lipase testing.
Physical therapy, occupational therapy, nutritional consultations may be suggested.
Patients need diabetes education. The patient needs to closely follow up with his primary care provider for diabetes management and prevention. Patients who smoke need to be given resources to quit smoking.
The patient should undergo follow up surveillance every 6 months for a year after the surgery with CT scans of the abdomen. If by 1 year nothing is seen, then patients can follow up annually and have imaging with MRCP to reduce radiation exposure.
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