Serous Cystadenoma of the Pancreas

Serous cystadenoma of the pancreas is a benign cystic neoplasm composed of glycogen rich cuboidal epithelium lining many small cysts. It has almost no malignant potential.

It accounts for 1% to 2% of pancreatic neoplasms and about 16% of cystic pancreatic neoplasms. The usual patient is a woman in her 60s, and the tumour is often found incidentally on imaging. It is more common in von Hippel-Lindau disease.

The microcystic form (many cysts under 2 cm with a central scar, sometimes calcified in a sunburst pattern) is the commonest. Oligocystic or macrocystic forms have fewer, larger cysts and can resemble mucinous tumours. The average growth rate is about 4 mm each year, higher in lesions over 4 cm. Serous cystadenocarcinoma is extremely rare.

Pathophysiology.

Loss of function of the VHL gene on chromosome 3p is found in most sporadic and syndromic tumours. Clear cells line the cysts, which contain thin watery fluid.

Most are asymptomatic. Large tumours cause abdominal pain, a mass, early satiety, jaundice (head lesions), pancreatitis, gastric outlet obstruction and, rarely, haemorrhage. Features of von Hippel-Lindau disease (retinal, cerebellar, renal and adrenal lesions) are sought when multiple or young.

Magnetic resonance imaging or CT shows a lobulated lesion of multiple cysts under 2 cm, with a honeycomb or sponge appearance, thin septa that enhance and a central scar or calcification. Endoscopic ultrasound shows a microcystic or honeycomb pattern. Cyst fluid, if aspirated, is thin and clear, with low carcinoembryonic antigen (under 5 ng/mL) and low amylase, and cytology with glycogen rich cells. Test for von Hippel-Lindau disease when multiple lesions or young age.

Differential diagnosis.

• Mucinous cystic neoplasm.
• Intraductal papillary mucinous neoplasm.
• Cystic neuroendocrine tumour.
• Solid pseudopapillary neoplasm.
• Pancreatic pseudocyst.
• Metastatic renal cell carcinoma.

Observe asymptomatic lesions with a confident diagnosis, with magnetic resonance imaging at 1 year and then every 2 to 3 years, and stop surveillance when growth is stable and the diagnosis is secure. Resect lesions that cause symptoms (pain, obstruction or pancreatitis), grow rapidly (over 2 cm in a year), or are uncertain, particularly lesions over 4 cm in younger patients. Enucleation or pancreatic resection preserving as much pancreas as possible is usual. No drug therapy is needed.

Monitoring. Magnetic resonance imaging at 1 year, then every 2 to 3 years for lesions under observation; no follow up is needed after complete resection of a benign lesion.

Referral and escalation. Pancreatic surgery or a pancreatic cyst clinic for symptomatic, large or uncertain lesions; genetics for von Hippel-Lindau disease.