Pancreas cysts

Some epithelial mesotheliomas are composed of small cysts formed by uniform cuboidal mesothelial cells and associated numerous blood vessels (Fig. 12.68). This type of mesothelioma may be difficult to differentiate from a vascular neoplasm. The epithelial mesothelial cells may contain intracytoplasmic hemosiderin (Fig. 12.69). The immunophenotype of such neoplasms is identical to that of other epithelial mesotheliomas. The vascular proliferation may be related to an endothelial growth factor produced by neoplastic mesothelial cells.Adenomatoid tumors are localized benign mesothelial proliferations that most frequently occur in the epididymus and cornua of the uterus.Adenomatoid tumors have been identified in the adrenal gland and pancreas. These tumors are formed by uniform small cuboidal cells and can appear invasive. They express keratin and other markers of mesothelial cells and have the characteristic ultrastruc-tural features of mesothelial cells. Adenomatoid tumors have also been reported in the pleura. Hyperplastic... 

Motoo Y, Kawashima A, Watanabe H, et al. Undifferentiated (anaplastic) carcinoma of the pancreas showing sarcomatous change and neoplastic cyst formation. Int J Pancreatol. 1997 21 243-248. 

Sperti C, Pasquali C, Perasole A, et ak Macrocystic serous cyst-adenoma of the pancreas clinicopathologic features in seven cases. Int J Pancreatol. 2000 28 1-7. 

Mohr VH, Vortmeyer AO, Zhuang Z, et ak Histopathology and molecular genetics of multiple cysts and microcystic (serous) adenomas of the pancreas in von Hippel-Lindau patients. Am J Pathol. 2000 157 1615-1621. 

Partial duodenal obstruction may be produced by duodenal stenosis, duodenal web, Ladd s bands, midgut volvulus, annular pancreas, preduodenal portal vein, and duplication cyst. Plain radiographs show gaseous distension of the stomach and duodenum with a normal or diminished quantity of air in the small bowel. Content studies may be necessary to differentiate between midgut volvulus and partial duodenal obstruction caused by a web or stenosis (Auringer and Sumner 1994). Sonography is helpful to rule out extraluminal causes such as a duplication cyst. 

CT might also play an important role. It allows for good characterization of intrahepatic cysts, the distal part of the common bile duct, and the head of the pancreas, and in post-surgical patients it gives a very accurate evaluation of the biliary-enteric anastomosis. However, cholangiography can dem-... 

On US, the pancreas with CF is characteristically of an echogenic texture secondary to fatty infiltration (Fig. 4.17). An enlarged pancreas may be seen initially with a subsequent atrophy later in life. Pancreatic duct dilatation and calcifications may be seen. Small cysts (anechoic areas) without vascular communication can be identified. Although a hyperechogenic pancreas is very typical of CF, some other diseases such as Schwachman-Diamond syndrome (exocrine pancreas insufficiency associated with bone marrow dysfunction, cyclic neutropenia, metaphyseal diastasis and growth retardation), hemosiderosis, chronic pancreatitis, and administration of steroids may also reveal this feature (Feigelson et al. 2000). 

CT may demonstrate an atrophic, fatty pancreas with heterogeneous attenuation. Areas of low attenuation will correspond to cysts, while areas of high attenuation will represent calcifications. Partial or total fatty and fibrous replacement are also commonly seen in these patients. There may be a correlation between the degree of fatty infiltration and the pancreatic exocrine dysfunction (Feigelson et al. 2000). 

Von Hippel-Lindau disease (VHL) is an autosomal dominant condition secondary to an alteration in a tumor suppressor gene on chromosome 3. It has incomplete penetrance and is characterized by hemangioblastomas in the retina, CNS, renal cell carcinoma, endolymphatic sac tumors, pheochro-mocytomas, papillary cystadenoma of the epididymis, angiomas of the liver and kidney, cysts of the liver, kidney and epididymis, and pulmonary arteriovenous shunts (Fig. 4.18a-c). In the pancreas, VHL may have multiple presentations, the most common being the presence of multiple small pancreatic cysts with calcifications in 40% of cases. Serous cystad-enomas, solid nonfunctional islet cell tumors, and adenocarcinoma are less common (Richard et al. 2004). 

CT and US may demonstrate a low attenuating lesion or an anechoic defect typically located in the tail of the pancreas. This lesion can be unilocular or multilocular with multiple septae. The differential diagnosis includes cyst of renal origin, as well as choledochal, mesenteric, ovarian, and urachal cysts. ERCP and HIDA scans can be used to identify communication with the pancreatic duct or biliary tree. 

Fig. 4.18a-e. Von Hippel-Lindau. a-cMRI Inhomogeneous hemangioblastomas in the pons. d,eUS multiple cysts of varying sizes in the pancreas (asterisks)... 

On the other hand> pancreatic pseudocysts represent the most common cystic masses in the pancreas. Pseudocysts are usually fluid collections with a thick wall that arise secondary to infections or trauma. Differentiation between a true cyst and a pseudocyst hy imaging is very difficult and can only be done by microscopic examination. 

MRCP is a very useful imaging tool used to identify possible etiologies of pancreatitis such as abnormal union of the pancreatobiliary junction, choledochal cyst, or pancreas divisum, in patients with unknown cause (Arcement et al. 2001 Hirohashi et al. 1997). 

In volvulus, due to other causes, the location and axis of the mass with whirlpool appearance can vary. In a mesenteric cyst with volvulus of most of the small bowel, the mass is seen below the pancreas, as seen in volvulus of malrotation (Vijayaraghavan et al. 2004). Alternatively, when the volvulus involves only a segment of small bowel, the mass is located close to the umbihcuSjjust above or to the right of it. The best... 

Fig. 3.6. Coronal reformatted image of endoscopically proven pseudocyst based on analysis of cyst fluid at aspiration. Coronal reformatted CT image (left) and coronal single shot fast spin echo MR image (right) shows pseudocyst (arrow) in the tail of the pancreas. Similar information is obtained without the use of radiation at MR imaging...

Fig.7.8a,b. Pyogenic abscess, a Pyogenic abscess in a 35-year old man status post laparoscopic right hepatectomy due to an hydatid cyst. Portal venous-phase contrast-enhanced CT scan shows a thick-walled cystic lesion with homogeneous low attenuation. b Pyogenic abscess with presence of gas within the lesion in a 52-year-old man with fever, head of pancreas neoplasia (not resectable due to superior mesenteric vein infiltration) and recent portal thrombosis. An axial portal phase CT scan shows an hypoattenuating lesion with non-homogeneous content and gas inside... 

Fig. 7.21. Image from a 54-year-oldman obtained 5 months after simultaneous pancreas-kidney transplantation with graft pancreatitis and pseudocyst formation. Sonography shows large, partly septated cyst (white asterisk) adjacent to pancreatic graft (not shown) consistent with peripancreatic pseudocyst...

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