The major pancreatic lesions associated with VHL include pancreatic cysts, serous microcystic adenomas and adenocarcinomas. Islet cell tumors are considered separately. The pancreatic cyst is by far the most common of these lesions but its frequency varies greatly with the particular family studied ranging from 0% in two large families (10,84) to 93% in others (63). The earliest age of discovery is reported to be 15 years (82) but pancreatic involvement usually comes to light between the ages of 20-40 during screening studies or work ups for other abnormalities.
Cystic involvement is found throughout the pancreas and has no predilection for a particular site. Cysts are composed of epithelial lined collections of serous fluid that vary in size from several millimeters to over 10 cm. The serous cystadenoma (or microcystic adenoma) is a grape-like cluster of multiple microscopic and macroscopic (2mm-2cm in diameter) cysts separated by thickened walls of stroma (72,88,89) (Figure 17).
Figure 17. Serous cystadenoma of the pancreatic head. This patient demonstrates
a typical appearance of a serous cystadenoma (arrow) with central calcifications
and innumerable cysts creating a "mass". Serous cystadenomas can
create mass effect but in themselves do not require resection. Multiple
solid and cystic (curved arrows) renal lesions are also present. This patient
died of metastatic renal cell carcinoma.They are often arranged in a stellate pattern with a central nidus which may be calcified or scar-like (90,91,92). The cysts are lined by cuboidal epithelium rich in glycogen but containing no mucus (92). These tumors are benign and only become evident when they cause bile duct obstruction. The mucinous cystadenoma of the pancreas, a premalignant lesion, is not associated with VHL (91). Since cysts and cystadenomas of the pancreas are benign in VHL, they need not be removed.
Pancreatic lesions are generally the least symptomatic among the lesions of VHL, however, occasionally very debilitating symptoms can result. Strategically located lesions such as microcystic adenomas in the head of the pancreas can cause symptomatic biliary obstruction or pancreatitis and may require biliary stents (50,92,93,94). Cysts may enlarge sufficiently to cause local pain or early satiety due to extrinsic compression (95) (Figure 18).
Figure 18. Large pancreatic cyst causing symptoms of early satiety. This cyst (C)
is unusually large for VHL and caused pain and early satiety. It was drained
percutaneously and sclerosed with hypertonic saline with beneficial results.
A fluid debris level (arrow) is seen in the tail of the pancreas.We have treated such patients with percutaneous drainage and hypertonic saline sclerosis. The pancreas may become so replaced with multiple small cysts as to render it non-functional resulting in steatorrhea and diarrhea (Figure 19). Symptoms resolve with pancreatic enzyme replacement (88,96). Insulin dependent diabetes apparently as a result of cystic pancreatic replacement is also seen (8,50).
Figure 19. Complete replacement of the pancreas with cystic disease and
intrahepatic biliary dilation caused by extrinsic compression of the common bile
duct. Note also the renal cysts and masses. This patient had exocrine
pancreatic insufficiency.Pancreatic cysts and microcystic adenomas are most commonly detected with CT and ultrasound (38,72). The use of thin section CT improves the detection of lesions (91,93). Cyst walls enhance poorly or not at all. Calcifications are common throughout the pancreas. Microcystic adenomas are suggested by a focal enlargement of the pancreas composed of small cysts which are radially aligned with a central calcified scar, some of which are so small as to be indistinguishable from each other (90). However, it is not always possible to distinguish a cluster of cysts from a microcystic adenoma; nor is the distinction clinically important (89). Serous microcystic adenomas may appear solid on ultrasound due the multiple acoustic interfaces caused by multiple microscopic cysts.
Additional pancreatic lesions that have been reported in VHL include adenomas (97), hemangioblastoma (50), and adenocarcinoma of the pancreas and ampulla of Vater (9,50,98). The evidence for the latter is convincing enough to justify a careful examination of the pancreas while monitoring the kidneys for neoplasia.
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