retrograde pancreatography, and angiography, and the use of radioactive tracer substances (e.g., 75 selenomethionine scans). If a space-occupying lesion is observed or suspected, the identity of the lesion must be further established. Cytologic techniques are currently the diagnostic methods of choice.
TABLE 39-1 COMMON LESIONS OF THE PANCREAS
Endoscopic cytologic sampling via the common bile duct, using US or retrograde pancreatography
Cytology of pancreatic juice
Transcutaneous, intraoperative, or EUS-guided FNA
Percutaneous transabdominal aspiration under US or CT guidance. The success of this method depends on the skill of the operator in guiding the needle to the target area and obtaining an adequate sample. The adequacy of the sampling procedure may be determined at the bedside by rapid microscopic examination of aliquots of the samples by trained personnel. In our experience, adequate samples can be obtained from nearly all pancreatic cancers; however, in some cases the aspiration must be repeated.
EUS-guided FNA. This is a newer approach that can be utilized to sample small pancreatic carcinomas (Chang et al, 1997; Jhala et al, 2003). The procedure is tedious and requires operator experience and collaboration between the cytopathologist and endoscopist. It is now the standard of practice in large medical centers.
Direct visualization or palpation of the pancreas at the time of a laparotomy. This was the initial method used for cytologic investigations of the pancreas before reliable imaging techniques became available (Arnesjo et al, 1972). The advantage of this method is that it can precisely locate the pancreatic lesion with excellent accuracy and very few complications (Hastrup et al, 1977; Stormby, 1979; Alpern and Dekker, 1985; Soudah et al, 1989; Edoute et al, 1991; Blandamura et al, 1995; Saez et al, 1995). The samples are not contaminated by cellular material from serosal, gastric, or intestinal tissues.
have been reported include cases of acute pancreatitis, needle tract seeding of pancreatic carcinoma, and pancreatic fistula (McLoughlin et al, 1978; Ferrucci et al, 1979; Simms et al, 1982; Rashleigh-Belcher et al, 1986; Bergenfeldt et al, 1988; Fornari et al, 1989; Rosenbaum and Frost, 1990). A case of bile peritonitis was encountered in a patient with carcinoma of the head of pancreas and a distended Courvoisier gall bladder. The perforation was immediately apparent because of the presence of bile in the syringe; however, the patient recovered after laparotomy and treatment with antibiotics (Koss et al, 1992). The frequency of complications from FNA is much lower than that associated with incisional pancreatic biopsies.
of small clear cells, approximately five times the size of an acinus (Fig. 39-1B). The islets do not maintain communication with the acinar or ductal system, and they secrete their products directly into the bloodstream. Depending on the hormones produced, the islet cells may be classified as α cells (which produce glucagon), β cells (insulin), δ cells (somatostatin), G1 cells (gastrin), and PP cells (polypeptide). These cell types are identified on the basis of immunohistochemistry or electron microscopy (Mukai et al, 1982). Regardless of type of cell involved, tumors derived from islet cells, known as pancreatic endocrine neoplasms, are morphologically similar to each other.
of cancer. The absence of single cancer cells is another reason to regard such clusters as benign.
Figure 39-3 Cytology of endocrine pancreas. A. A fortuitous finding of a large cluster of normal islet cells in a patient with sclerosing cholangitis and complete destruction of the exocrine pancreas documented at autopsy (B).
may also be associated with pancreatitis (Marshall, 1993). The pathogenesis of pancreatitis is poorly understood. The formation of pseudocysts may be a consequence of pancreatitis (see below).
Figure 39-4 Other benign cells observed in pancreatic aspirates. A. Gastric epithelial mucus-producing cells are larger than normal ductal cells and have sharper cytoplasmic borders. Lesions of the body of pancreas, aspirated through the posterior gastric wall by an endoscopic ultrasound (EUS)-guided needle, may show an abundance of such cells, causing diagnostic difficulty. Compare with the illustrations of low-grade mucinous cystic tumors in Figure 39-8. B. Colonic epithelium. A strip of colonic mucosa that is rich in pale goblet cells and may resemble mucinous cystadenoma. C. Hepatocytes are occasionally derived from the left lobe of the liver. They show dense pink cytoplasm and prominent nucleoli. D. Ganglion cells, derived from sympathetic ganglia, may be occasionally seen in aspirations of the pancreas.
important factors in the differential diagnosis of inflammatory atypia of ductal cells versus well-differentiated ductal carcinoma are discussed below in reference to carcinoma, and are summarized in Table 39-3 (see below). An additional confounding factor is that ductal carcinoma and chronic fibrosing pancreatitis may coexist and may account for at least some of the false-negative diagnoses on FNA of this organ.
etiology and pathogenesis. These tumors occur predominantly in elderly women (mean age of 66 years), but they may also occur in men, and are usually, but not always, located in the body and tail of the pancreas (Compagno and Oertel, 1978; Albores-Saavedra, 1990). A macrocystic variant of this tumor was described by Lewandrowski et al (1992). The tumor can be asymptomatic and incidently found during abdominal examination for unrelated disease, or it may cause nonspecific symptoms related to its bulk, such as abdominal pain, nausea, and vomiting. Grossly, these tumors are well-circumscribed and large, with an average diameter of 10 cm. The cut surface has a characteristic sponge-like appearance due to the presence of numerous cysts of variable size (hence the name microcystic adenoma).
no first-hand experience with such a lesion in aspiration smears.
careful scrutiny of smears from high-grade mucinous cystic tumors reveals papillary or three-dimensional groups with obvious nuclear atypia. Frankly malignant tumors of this category are classified as mucinous adenocarcinoma (see Fig. 39-16A,B) and are cytologically identical to colloid (mucinous noncystic carcinoma; see below). A positive mucin stain excludes serous cystadenoma (Table 39-2). Rubin et al (1994) reported that benign and malignant mucinous cystic neoplasms can be differentiated by the level of the tumor marker CA 15.3 in the cyst fluid.
Figure 39-8 Neoplastic cysts of the pancreas. A. Mucinous cystadenoma. A large sheet of epithelial cells in a honeycomb-like arrangement is shown on a background of thick, clear mucus. No nuclear abnormalities or nucleoli are seen. Compare with normal pancreatic ductal cells and gastric mucus cells (Figs. 39-2B and 39-4A). B. Dispersed goblet cells, elongated by the smearing process, in a background of mucus. C. Borderline intraductal papillary mucinous tumor. The smear shows numerous mucus-producing cells. An occasional nucleolus can be noted. D.Get Clinical Tree app for offline access
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