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Sindbis virus (SINV) infection induces eIF2α phosphorylation, which leads to stress granule (SG) assembly. SINV infection also stimulates autophagy, which has an important role in controlling the innate immune response. The importance of autophagy to virus-induced translation arrest is not well understood. In this study, we show that the autophagy protein ATG16L1 not only regulates eIF2α phosphorylation and the translation of viral and antiviral proteins, but also controls SG assembly. Early in infection (2hpi), capsids were recruited by host factors Cytotoxic Granule-Associated RNA Binding Protein (TIA1), Y-box binding protein 1 (YBX1), and vasolin-containing protein 1 (VCP), to a single perinuclear body, which co-localized with the viral pattern recognition sensors, double stranded RNA-activated protein-kinase R (PKR) and RIG-I. By 6hpi, there was increased eIF2α phosphorylation and viral protein synthesis. However, in cells lacking the autophagy protein ATG16L1, SG assembly was inhibited and capsid remained in numerous small foci in the cytoplasm containing YBX1, TIA1 with RIG-I, and these persisted for over 8hpi. In the absence of ATG16L1, there was little phosphorylation of eIF2α and low levels of viral protein synthesis. Compared to wild type cells, there was potentiated interferon protein and interferon-stimulated gene (ISG) mRNA expression. These results show that ATG16L1 is required for maximum eIF2α phosphorylation, proper SG assembly into a single perinuclear focus, and for attenuating the innate immune response. Therefore, this study shows that, in the case of SINV, ATG16L1 is pro-viral, required for SG assembly and virus replication.

Objective: The goal of this prospective randomized study was to determine whether isosmolar contrast material offers an advantage over low-osmolar contrast material for delayed venous opacification in CT venography. SUBJECTS AND METHODS. We prospectively enrolled 200 adult outpatients. Patients were randomized to receive either the low-osmolar (hyperosmolar to blood) nonionic contrast medium, iohexol, or the nonionic isosmolar contrast medium, iodixanol. Images were obtained before contrast administration and 180 sec after contrast administration through the pelvis at the level of the external iliac vessels. Opacification of the external iliac vessels was assessed both objectively and subjectively., Results: The arterial and venous densities before contrast administration were approximately 45 H for both groups. On delayed images obtained after contrast administration, the mean venous density was 95.2 H for iohexol and 101.4 H for iodixanol. Changes in venous density due to administration of iohexol and iodixanol were 49.8 and 56.1 H, respectively. This 12.5% difference was highly significant (p = 0.002). Sixty-six percent of the images in the iodixanol group were rated either 4 (good) or 5 (excellent), whereas only 36% of the iohexol group achieved a similar rating on our subjective rating scale. This difference was statistically significant (chi(2) = 16.4, p < 0.001, df = 1)., Conclusion: Our study shows that isosmolar contrast material provides significant improvement in delayed opacification of the external iliac vessels in comparison with conventional low-osmolar contrast medium (hyperosmolar to blood).

Objectives: To describe the imaging, clinical and pathological features of primary splenic lymphoma using a strict definition., Methods: Of 21 cases, plain films were available in nine, sonograms in 10 and CT in 16. We categorized the spleen as either normal, enlarged with no focal defects (type 1), studded with miliary masses (type 2), containing multifocal masses of varying size (1-10 cm) (type 3) or containing a solitary large mass >5 cm without (type 4A) or with (type 4B) central hypodensity/anechoic areas., Results: Clinical presentations were left upper quadrant pain, weight loss and/or fever. One case was found incidentally on CT. Fourteen were type 4A, three type 4B, four type 3 and none were type 1 or 2. Nine of 10 cases were hypoechoic. In 11/12 cases with enhanced scans, the lesions are hypodense relative to the splenic parenchyma, and in one case, the lesion was necrotic. Rim enhancement was seen in one case., Conclusion: Primary splenic lymphoma usually presents as a mass or masses rather than with splenomegaly alone. Splenectomy may be required for diagnosis.

Purpose: To determine the imaging features of duodenal gangliocytic paraganglioma that can be used to differentiate this mass from other lesions., Materials and Methods: Imaging, histopathologic, and surgical findings in five patients with proved gangliocytic paraganglioma were reviewed. The most common symptom at presentation was abdominal pain (n = 3). All patients underwent computed tomography (CT), two underwent ultrasonography (US), and one underwent magnetic resonance (MR) imaging. Imaging findings were correlated with findings from surgical resection specimens in all cases., Results: All lesions were located around the second portion of the duodenum and were 3-13 cm in diameter (mean, 6.5 cm). Two extended laterally to the duodenum, two extended medially, and one was intraluminal. All appeared solid and homogeneous on US, CT, and MR images and had homogeneous contrast material enhancement on CT and MR images. All were solid, with a prominent vascular network, but no cystic hemorrhage or necrosis was noted at pathologic examination., Conclusion: The imaging features of gangliocytic paraganglioma are suggestive enough for the prospective diagnosis and differentiation of this benign mass from other lesions.

Purpose: To correlate the imaging and pathologic features of undifferentiated (embryonal) sarcoma (UES) and account for the discrepancy between the solid appearance at ultrasound (US) and the almost cystlike appearance at computed tomography (CT) and magnetic resonance (MR) imaging., Materials and Methods: The clinical, pathologic, and imaging findings in 28 patients (age range, 3-49 years) with pathologically proved UES were retrospectively reviewed. All patients underwent at least one cross-sectional imaging study to include CT (27 patients), US (21 patients), and MR imaging (six patients). Tumor size, gross morphology (n = 27), histologic features, and proportion of solid and cystlike components were evaluated and correlated to the imaging findings., Results: The mean transverse diameter of the tumors was 14 cm (range, 10-25 cm). At gross examination, the tumors were predominantly solid (mean, 83% of tumor volume), and pathologic and US findings were concordant. Conversely, CT scans showed low attenuation (approximately that of water) in 88% of the tumor volume and T2-weighted MR images showed high signal intensity (approximately equal to that of cerebrospinal fluid) in 89% of the tumor volume., Conclusion: UES shows a misleading cystlike appearance at CT and MR imaging compared with US and pathologic findings. In a child or young adult with a liver tumor, this finding is useful in making a prospective diagnosis and avoiding misguided attempts at drainage.

Islet cell tumors are rare pancreatic or peripancreatic neoplasms that produce and secrete hormones to a variable degree. These tumors are best divided on clinical grounds into those that produce a recognizable, clinically evident endocrine syndrome (ie, functioning) and those that exhibit no clinical evidence of hormone production (ie, clinically silent). Clinically silent tumors produce symptoms due to mass effect because of their large size. They are often partially cystic or necrotic. Functioning islet cell tumors usually manifest earlier in the course of the disease because of the distinctive signs and symptoms of the associated endocrine syndrome. Clinically silent and functioning tumors cannot be histologically distinguished reliably even with the use of immunohistochemical stains. Insulinoma and gastrinoma, the two most common functioning lesions, are typically small homogeneous masses. Other functioning islet cell tumors include glucagonoma, somatostatinoma, vipoma, and adrenocorticotropic hormone-producing tumor. Larger tumors are associated with calcification, cystic degeneration and necrosis, and a more aggressive behavior (local and vascular invasion as well as distant metastases). There are many different techniques for detection and characterization of these lesions that are usually chosen according to the radiologist's experience and preference. Treatment and prognosis of these lesions depend on the hormone produced, their size, and their behavior.

Objective: The objective of this study was to determine the clinical, radiographic, and pathologic findings of Meckel's enteroliths, a rare complication of Meckel's diverticulum., Materials and Methods: Of 84 cases of Meckel's diverticulum, eight (10%) were found at surgery to contain enteroliths. Abdominal radiographs and barium studies of these eight patients were reviewed retrospectively. Medical and pathologic records were also reviewed., Results: At the time of diagnosis, the median age of the eight patients with Meckel's enteroliths was 45 years old. Six patients were male, and two were female. All eight patients were symptomatic, but symptoms were chronic in six patients (75%). Meckel's enteroliths were seen on abdominal radiographs in seven patients (88%). The stones had an average diameter of 3 cm (range, 1-5 cm). Five patients had multiple opaque stones, and two patient had solitary stones (total number of stones, 18). Sixteen of the enteroliths were revealed as peripheral calcified stones with radiolucent centers; two were revealed as laminated stones. One patient had a Meckel's stone ileus due to extrusion of an enterolith into the lumen that subsequently caused small-bowel obstruction. Histologically, all Meckel's diverticula with enteroliths contained intestinal mucosa lining without ectopic gastric mucosa., Conclusion: Meckel's enteroliths are a rare complication of Meckel's diverticulum. Nevertheless, this entity should be included in the differential diagnosis of abdominal calcification when a peripheral calcified stone or, less commonly, a laminated stone is detected in the lower abdomen on radiographs of adults with chronic abdominal pain or gastrointestinal blood loss.

Purpose: To demonstrate the radiologic appearance of linitis plastica in non-Hodgkin lymphoma of the stomach and to correlate radiologic and pathologic findings., Materials and Methods: Of 34 cases of non-Hodgkin lymphoma of the stomach in the radiologic archives of the Armed Forces Institute of Pathology, nine had a linitis plastica appearance at barium study. The radiologic, endoscopic, and pathologic findings of these cases were reviewed., Results: All nine patients (six with primary gastric lymphoma, three with generalized lymphoma with stomach involvement) were symptomatic. Images from barium studies revealed a linitis plastica appearance with narrowing of the gastric antrum and/or body (n = 5), narrowing of the body and/or fundus (n = 3), and diffuse gastric narrowing (n = 1). On CT scans (n = 7), marked circumferential soft-tissue thickening (average thickness, 2.9 cm) of the gastric wall was seen. Patients were treated with subtotal gastrectomy and gastrojejunostomy (n = 5) or total gastrectomy and esophagojejunostomy (n = 4). In all cases, histopathologic specimens revealed a thickened gastric wall with lymphomatous cell infiltration. Wall thickening was associated with areas of fibrosis in only one case., Conclusion: Non-Hodgkin gastric lymphoma should be recognized as another cause of linitis plastica, especially in patients with a history of lymphoma or evidence of generalized lymphoma at presentation.

Objective: Leiomyosarcomas of the esophagus are rare malignant smooth-muscle tumors that have been described only anecdotally in the radiology literature. The objective of this study was to evaluate the clinical and radiographic findings of this unusual lesion., Materials and Methods: A search of the radiology archives of the Armed Forces Institute of Pathology revealed 10 cases of esophageal leiomyosarcomas. Clinical and radiographic findings were reviewed retrospectively., Results: All but one patient presented with dysphagia. The average duration of the dysphagia was 6.7 months, but five patients had dysphagia for 3 or fewer months. Frontal chest radiographs revealed a mediastinal mass in five patients. Barium studies revealed intramural lesions in six patients, intraluminal lesions in two, and infiltrative lesions in two. The intramural Lesions all had large exophytic components, and three contained ulceration or tracking. One of the intraluminal lesions appeared as a polypoid expansile mass and the other, as a smooth expansile sausage-shaped mass mimicking a fibrovascular polyp. CT revealed a mass involving the esophagus in five patients; three of these patients had heterogeneous lesions containing large exophytic components, central areas of low density, and extraluminal gas or contrast material within the tumor. In two patients, MR imaging revealed large masses that were isointense with skeletal muscle on T1-weighted images and hyperintense on T2-weighted images., Conclusion: Our experience suggests that esophageal leiomyosarcomas have radiographic findings similar to those of leiomyosarcomas elsewhere in the gastrointestinal tract. Esophageal leiomyosarcomas have a better prognosis than squamous cell carcinomas and are often amenable to surgical cure.

Purpose: To determine the radiographic findings of small-cell carcinoma of the esophagus., Materials and Methods: The authors retrospectively reviewed barium studies as well as medical and pathologic records for three cases of small-cell carcinoma of the esophagus contributed to the radiologic archives of the Armed Forces Institute of Pathology., Results: Two patients presented with dysphagia and one with chest pain. In all three patients, barium studies revealed a smoothly marginated, sessile mass with a relatively flat central ulcer on the right postero-lateral wall of the midesophagus below the level of the carina. The masses all were 4-5 cm in diameter, and the ulcers were 2-3 cm in diameter. In all three patients, the results of endoscopy confirmed the presence of a sessile mass with central ulceration in the midesophagus., Conclusion: Small-cell carcinomas of the esophagus can have similar findings on barium studies. Although these findings are more likely to be caused by squamous-cell carcinoma, it is important to obtain endoscopic biopsy specimens, because preoperative histologic diagnosis of small-cell carcinoma can dramatically alter the management of these cases.

Purpose: To evaluate the clinical, pathologic, and imaging findings of solid and papillary epithelial neoplasm (SPEN) of the pancreas and to correlate imaging and gross pathologic features., Materials and Methods: A retrospective review was performed in 56 patients (53 female and three male patients aged 10-74 years [mean age at diagnosis, 25 years]) with pathologically proven SPEN of the pancreas. All patients underwent computed tomography (n = 49), ultrasonography (n = 31), or magnetic resonance (MR) imaging (n = 9). Tumor size, location, and imaging features were evaluated and correlated with gross pathologic and histologic features., Results: Mean transverse diameter of these tumors was 9.0 cm (range, 2.5-17.0 cm). They were localized to the tail (n = 30), head (n = 18), and body (n = 8) of the pancreas. All tumors contained some degree of internal hemorrhage or cystic degeneration, and all were well encapsulated. Areas of hemorrhagic degeneration ranged from solid friable tumor to gelatinous or cystic cavities and therefore demonstrated variable imaging features. Calcification was noted in 16 patients. Fluid-debris levels were noted in 10 patients., Conclusion: Imaging studies of SPEN of the pancreas consistently demonstrate variable degrees of hemorrhagic degeneration. Calcification is common. Characteristic fluid-debris levels and signal intensities seen with MR imaging indicate blood products. In the appropriate clinical setting, these findings are useful in making a prospective diagnosis.

Purpose: To determine the clinical, radiologic, and pathologic findings of inverted Meckel diverticulum by retrospectively reviewing a large series of cases., Materials and Methods: Among 84 cases of Meckel diverticulum, 18 (21%) were found at surgery to be inverted into the lumen of the bowel. Thirteen of these 18 (72%) cases were associated with small bowel intussusception and five (28%) were not., Results: All 18 patients (median age at time of diagnosis, 32 years) were symptomatic, but the symptoms were subacute or chronic in 14 (78%). At barium examination in 15 cases, inverted diverticulum was depicted in 10 (67%) as a solitary, elongated, smoothly marginated, often club-shaped intraluminal mass in the distal ileum. At computed tomography (CT) in three cases, a central area of fat attenuation was surrounded by a thick collar of soft-tissue attenuation. At ultrasound (US) in two cases, a target-like mass contained a central area of increased echogenicity. At pathologic examination in all cases, the inverted sac contained mesenteric fat., Conclusion: Inverted Meckel diverticulum occurs more commonly than previously recognized and is associated with characteristic findings at barium examination, CT, and US.

Purpose: To reassess the clinical and radiologic findings in patients with esophageal leiomyomatosis., Materials and Methods: A search of the authors' radiologic archives revealed six cases of esophageal leiomyomatosis in a 22-year period. The clinical findings and radiologic images were reviewed retrospectively., Results: The average age of the patients was 10.8 years (range, 6-18 years). Five patients presented with slowly progressive dysphagia. Barium studies revealed smooth, tapered narrowing of the distal esophagus in five patients and characteristic defects on the superomedial aspect of the gastric fundus abutting the cardia, presumably due to bulging of this thickened mass of muscle into the stomach, in four patients. In two patients, computed tomography (CT) revealed marked thickening of the distal esophageal wall., Conclusion: Esophageal leiomyomatosis can be suggested in a pediatric patient with long-standing dysphagia in whom smooth, tapered distal esophageal narrowing is seen at barium study and circumferential esophageal wall thickening is seen at CT.

Objective: Fibrovascular polyps of the esophagus are rare benign nonneoplastic intraluminal masses. Most published reports of patients with these polyps have been anecdotal. The purpose of this study was to reassess the clinical, radiographic, and pathologic findings in a relatively large series of patients with this unusual tumorlike lesion., Materials and Methods: A search of the radiologic archives of the Armed Forces Institute of Pathology revealed 16 cases of fibrovascular polyps of the esophagus. We reviewed the clinical, radiographic, and pathologic findings in these 16 cases., Results: All 16 patients were symptomatic. Fourteen (87%) had dysphagia and four (25%) had respiratory symptoms. The average duration of symptoms was 17 months, but seven patients (44%) had symptoms for 6 or fewer months. Two patients (12%) had a history of regurgitating the tumor into the pharynx or mouth, but none had the known complication of asphyxiation due to occlusion of the larynx. Chest radiographs revealed a right-sided superior mediastinal mass and/or anterior tracheal bowing in seven patients (44%). Barium studies revealed smooth but variably lobulated intraluminal masses that originated in the lower cervical esophagus and had variable sizes and distal extents, with an average length of 15 cm. Depending on the amount of fat and fibrovascular tissue in the lesion, CT revealed a heterogeneous appearance in four patients, lesions of predominantly fat density in two, and lesions of predominantly soft-tissue density in two., Conclusion: Knowledge of the clinical and radiographic features of fibrovascular polyps of the esophagus is important because surgical removal of these lesions is warranted in most patients.

Focal nodular hyperplasia (FNH) is a benign hepatic tumor that likely represents a local hyperplastic response of hepatocytes to a congenital vascular anomaly. It is most commonly seen in middle-aged women and is typically a solid mass measuring less than 5 cm in diameter. Most lesions have central scars that contain thick-walled vessels that provide excellent arterial blood supply; hemorrhage, necrosis, and infarction are, therefore, extremely unusual. Characteristic imaging features include a hypervascular homogeneous tumor with a central scar and with both hepatocellular and reticuloendothelial function. Ultrasonography, computed tomography, scintigraphy, and magnetic resonance imaging all offer different advantages in the detection and characterization of FNH. There is excellent correlation between the pathologic and imaging features of FNH. In many cases, it is possible to obtain a prospective imaging diagnosis of FNH; however, in some cases, the distinction between FNH and other primary hepatic neoplasms is not possible. In these latter cases, close imaging follow-up, needle biopsy, or even surgical resection may be necessary.

Background: To determine if infarction and necrosis is the cause of the confusing soft tissue density on CT within intussuscepting lipomas of the colon., Methods: The clinical records, radiologic examinations, and pathologic specimens of all 13 cases of colonic lipomas collected from 1988 to 1994 studied by CT and surgically resected were retrospectively reviewed. Ten of these cases were associated with intussusception; the CT attenuation of the lead point was graded according to its relative fat/soft tissue density. Pathologic specimens were graded independently by a GI pathologist and graded according to the degree of infarction/fat necrosis., Results: The lipomas ranged from 4 to 7 cm in diameter (mean = 5 cm). Only one case with intussusception, and all three cases without, demonstrated pure fat attenuation on CT and demonstrated pure fat histologically. One case demonstrated soft tissue attenuation and corresponded with the most severely infarcted specimen histologically; two cases with similar but less severe infarction/fat necrosis corresponded with less than 25% fat attenuation. These latter three cases were originally misinterpreted as malignancies rather than lipomas. Six cases maintained greater than 50% fat density and intermediate amounts of infarction/fat necrosis., Conclusion: Lipomas may have an atypical appearance when intussuscepted due to varying degrees of infarction/fat necrosis.

Objective: The purpose of our study was to correlate the imaging and pathologic features of islet cell tumors with regard to tumor size, necrosis and cysts, calcification, malignant behavior, and functional status., Materials and Methods: We retrospectively reviewed the clinical, pathologic, and imaging features of all 133 cases of pathologically proved islet cell tumors of the pancreas seen at the Armed Forces Institute of Pathology. Clinical data, including the patients' symptoms and serologic characteristics, were used to distinguish hyperfunctioning tumors (those causing symptoms related to elevated serum polypeptide levels) from nonhyperfunctioning tumors; hyperfunctioning tumors were divided further into insulin-producing and non-insulin-producing types. All patients had at least one cross-sectional imaging study, including CT (n = 118), sonography (n = 42), or MR imaging (n = 22). Clinical, pathologic, and imaging features were evaluated and correlated with tumor size, necrosis and cysts, calcification, local invasion, vascular invasion, metastases, and functional status., Results: Islet cell tumors with areas of necrosis or cystic change found pathologically and on imaging studies (56/133) were larger (8.4 cm in mean transverse diameter) than homogeneous solid lesions (2.9 cm in mean transverse diameter) and were predominantly non-insulin producing (48/56) and nonhyperfunctioning (36/56). Of the 43 insulinomas, 35 were small (2.2 cm in mean transverse diameter), solid, and homogeneous. Larger size also was associated with calcification and malignant behavior, including local invasion, vascular invasion, and distant metastases., Conclusion: Our findings show that cystic and necrotic islet cell tumors are usually non-insulin-producing and nonhyperfunctioning neoplasms and larger than the typically solid and small insulinomas. Calcification, local invasion, vascular invasion, and metastatic disease are more commonly seen with larger neoplasms.

Purpose: To evaluate cross-sectional imaging in the distinction of biliary cystadenoma from cystadenocarcinoma and in the determination of the presence of ovarian stroma., Materials and Methods: In 34 patients, radiologic studies and specimen photographs and descriptions were reviewed retrospectively without knowledge of the patient group. Histologic features were reviewed without knowledge of the radiologic findings and analyzed for epithelial and stromal components. Correlation was made between the radiologic findings, gross morphologic features, internal fluid characteristics, and histologic features., Results: The 34 patients had 27 biliary cystadenomas, 22 with ovarian stroma, and seven cystadenocarcinomas, four with ovarian stroma. Gross morphologic and imaging features suggestive of biliary cystadenocarcinoma included internal septation and nodularity. Septation without nodularity was seen only in biliary cystadenoma. Nonbilious fluid was the only feature associated with the presence of ovarian stroma but was not distinguishable on images., Conclusion: Imaging studies accurately reflect the nodularity and septation seen grossly to distinguish biliary cystadenoma and cystadenocarcinoma but do not allow distinction of the presence or absence of ovarian stroma.

Gastrointestinal diseases are common in patients with the acquired immunodeficiency syndrome (AIDS). In this review, the radiologic and pathologic findings of these diseases in AIDS patients are illustrated with cases from the archives of the Armed Forces Institute of Pathology. Diseases are categorized in two etiologic groups, opportunistic infections and AIDS-related neoplasms. Opportunistic infections include those caused by viral, fungal, protozoan, and bacterial pathogens. The AIDS-related neoplasms of primary importance are Kaposi sarcoma and non-Hodgkin lymphoma. The radiologic findings of these gastrointestinal diseases are frequently nonspecific. However, interpretation of the images with knowledge of the underlying pathologic entities and the level of compromise of the immune system helps narrow the differential diagnosis and often helps identify the presumptive diagnosis.

Most radiologists are familiar with the clinical and radiologic features of the familial adenomatous polyposis syndromes [1]. The hamartomatous polyposis syndromes occur less frequently, however, and their radiologic and clinical manifestations are not as well known. This group of syndromes includes Peutz-Jeghers, multiple hamartoma, juvenile polyposis, Cronkhite-Canada, and Bannayan-Riley-Ruvalcaba. The predominant gastrointestinal lesion in these diseases is some form of hamartomatous polyp. The term hamartoma implies a nonneoplastic tumor or tumorlike condition composed of tissue elements normally present in the particular area [2]. In many of these syndromes, it is now recognized that hamartomatous polyps of the gastrointestinal tract coexist with adenomas and that adenomas may develop within hamartomatous polyps. Either situation may contribute to the frequent association of alimentary tract adenocarcinoma that occurs in most of these syndromes. Various types of benign mucocutaneous lesions are common and often lead to the correct diagnosis. Of greater importance is the frequent occurrence of other extraintestinal manifestations, including several forms of malignant disease. Because of this frequent association with both gastrointestinal and nongastrointestinal malignant tumors, early and accurate diagnosis of these syndromes is essential. Meticulously performed double contrast studies are the preferred radiologic procedures for the diagnosis of gastrointestinal polyps in all of these diseases.

Objective: The purposes of this study were to determine the frequency and characteristics of calcification and fibrosis in mesenteric carcinoid tumor as seen on CT scans and to evaluate their possible role in diagnosis., Materials and Methods: The CT findings in 29 cases of proved mesenteric carcinoid tumor were analyzed retrospectively. Tumors were assessed for size, margin, density, radiating strands, calcification, and associated thickening of the small-bowel wall. Matching histologic sections were available for 21 of the cases. They were reviewed independently for histologic pattern, degree of fibrosis, degree of infiltration along neurovascular bundles, necrosis, lymph node architecture, and calcification or ossification within the mass. CT and pathologic findings were then assessed for possible relationships., Results: Calcification was detected by CT in 70% (21 of 30) of mesenteric masses. Three patterns of calcification were noted: small, stippled calcification (n = 11); coarse, dense calcification (n = 7); and diffuse calcification (n = 3). All calcification was localized within areas of poorly cellular mature fibrous tissue. The degree of radiating strands detected by CT tended to increase with the degree of fibrosis seen histopathologically (p = .06)., Conclusion: Calcification in mesenteric carcinoid tumors was observed by CT in most cases of this series. The triad of a calcified mesenteric mass, radiating strands, and adjacent bowel-wall thickening should be considered highly suggestive of carcinoid tumor.

Ovarian carcinoma is the most common cause of death from a gynecologic malignant neoplasm. The typically advanced stage at presentation and aggressive nature of these neoplasms result in an overall 5-year survival rate of less than 40%. Most malignant ovarian neoplasms are of the surface epithelial cell type, which includes serous, mucinous, clear cell, endometrioid, and Brenner tumors. However, among the epithelial neoplasms, benign lesions are more common than malignant neoplasms, and other entities (including nonneoplastic masses) are far more common causes of a pelvic mass. Imaging studies (ultra-sound, computed tomography, and magnetic resonance imaging) can depict the tumor morphology: solid or cystic, unilocular or multilocular cystic, with or without thickening of the walls or septa, with or without papillary excrescences or other soft-tissue elements, and with or without calcifications. Evaluation of these morphologic characteristics allows attempted differentiation among malignant, benign neoplastic, and nonneoplastic lesions. Lesion characterization assists in surgical planning. Malignant neoplasms nearly always require laparotomy, whereas benign neoplasms may be managed laparoscopically. In the case of ovarian carcinoma, treatment is primarily surgical, and most patients also receive chemotherapy. Unfortunately, recurrence is common.

This article discusses a variety of non-neoplastic conditions that involve the stomach. Nonspecific gastritis and Helicobacter gastritis are discussed in detail as are other infectious diseases and the forms of hypertrophic gastritis. Non-neoplastic polyps unique to the stomach, hyperplastic polyps, and fundic gland polyps are also covered.

Cross-sectional imaging is playing an increasing role in diagnosis of diffuse liver diseases because it clarifies, in many cases, the overlap in clinical and laboratory manifestations often present in diffuse hepatic processes and thus may eliminate the need for a biopsy. Advances in cross-sectional imaging, particularly in magnetic resonance (MR) imaging, enable further characterization of hepatic parenchymal and architectural changes, allowing closer correlation with underlying pathologic changes. Advanced imaging techniques can be used to characterize a variety of metabolic, vascular, toxic, infectious, and neoplastic diffuse liver diseases. These include more common entities such as cirrhosis, Budd-Chiari syndrome, hemochromatosis, Wilson disease, fatty change, and diffuse neoplastic disease (hepatocellular carcinoma, metastasis, and lymphoma) and uncommon entities such as schistosomiasis, sarcoidosis, and amyloidosis. Correlation of computed tomographic and MR imaging findings with underlying pathologic features is helpful in understanding the gamut of diffuse diseases of the liver.

Germ cell tumors of the sacrococcygeal region include mature and immature teratomas and endodermal sinus tumor. Most sacrococcygeal teratomas are discovered in the newborn period as an obvious mass, but they may be detected prenatally. Endodermal sinus tumors are usually discovered later in early childhood. Pathologically and radiologically, teratomas are either both cystic and solid, predominantly cystic, or rarely solid. Over 50% have calcification or ossification. Most malignant teratomas have substantial solid components and may contain calcification. Treatment is surgical excision including coccygectomy. Malignant tumors are treated with both surgery and chemotherapy. Prognosis is excellent for teratoma, although local recurrences may occur. Malignant teratomas have had a dismal prognosis in the past, which has been improved with multiagent chemotherapy.

Although benign vascular tumors of the liver are extremely common (hemangioma is the most common), malignant vascular tumors of the liver are very rare. In the adult, these tumors are angiosarcoma, epithelioid hemangioendothelioma, and Kaposi sarcoma. All hepatic malignant vascular tumors share histologic characteristics, grow around and into vessels, and are grossly multifocal. They may be misdiagnosed histologically, particularly if only a biopsy sample is available. Although imaging findings are often non-specific, some features are suggestive or even characteristic of these neoplasms. Such features include previous exposure to thorium dioxide (Thorotrast) in cases of angiosarcoma, coalescence of multiple nodules into large peripheral masses in epithelioid hemangioendothelioma, and association between acquired immunodeficiency syndrome and cutaneous involvement in Kaposi sarcoma. Because hepatic malignant vascular tumors are often multiple, the main differential diagnosis is metastatic disease. There is no effective treatment for these tumors, and although survival time is variable, the prognosis is generally unfavorable.

Infantile hemangioendothelioma is a benign tumor of the liver composed of anastomosing vascular channels lined by plump endothelial cells. At initial presentation, most patients are 6 months of age or younger and have hepatomegaly or an abdominal mass. Congestive heart failure, bleeding, anemia, jaundice, and cutaneous or visceral hemangiomas may also be present. Grossly, the lesions are usually well circumscribed and may be focal, multifocal, or diffuse. Large solitary lesions are often associated with central hemorrhage or necrosis. Radiography reveals a mass that is occasionally calcified. Angiography reveals hypervascular lesions, often with arteriovenous shunting. A solid lesion with variable echotexture is noted at ultrasound. Computed tomography typically shows a low-attenuation solid lesion with peripheral enhancement. Central enhancement is often lacking except in smaller lesions. At magnetic resonance imaging performed with T2-weighted pulse sequences, the lesions usually have high signal intensity. Spontaneous regression of the tumor occurs, although patients may die of associated conditions.

Ampullary adenoma and adenocarcinoma are the benign and malignant neoplasms that arise from the glandular epithelium of the ampulla of Vater. When the tumors are small and confined to the ampulla, endoscopic and radiographic appearances may be normal. Larger intraampullary tumors appear as a prominent papilla or a mural mass. Computed tomography and ultrasound (US) show dilatation of the common bile duct or pancreatic duct in such cases, but the mass itself may not be seen. Larger lesions with intraduodenal extension are more easily identified with cross-sectional imaging. Endoscopic US is the best technique for tumor staging. The differential diagnosis includes other periampullary tumors such as pancreatic carcinoma, cholangiocarcinoma, and villous adenomas and adenocarcinomas of the duodenum. Mural masses of the periampullary duodenum including choledochocele and carcinoid should also be considered. Accurate diagnosis of ampullary tumors is important because the patients are usually candidates for a Whipple operation. Recent reports quote overall 5-year survival rates of 28%-70%. The prognosis is even better for patients with a limited stage of disease.

The Peutz-Jeghers polyp is an unusual type of hamartomatous polyp; its characteristic feature is a smooth muscle core arising from the muscularis mucosae and extending into the polyp. Peutz-Jeghers polyps vary in size and shape; are found in the stomach, small bowel, and colon; and are usually multiple. Peutz-Jeghers syndrome is an inherited condition that often remains undiagnosed until after the polyps are identified, despite mucocutaneous pigmented lesions on the lips and mouth of children or young adults. In the past, standard therapy involved removal of the polyps that produced intussusception, but now endoscopic removal of all polyps is recommended. The polyps are not premalignant, but a definite association exists between Peutz-Jeghers syndrome and gastrointestinal carcinoma. Evidence shows that the syndrome is associated with an increased risk of extraintestinal malignancy, especially carcinomas of the pancreas, breast, and reproductive organs.

Inflammatory fibroid polyps (IFPs) are uncommon lesions of the gastrointestinal tract. Only scattered case reports have appeared in the radiology literature. The authors reviewed the cases of 33 patients (20 women and 13 men; average age, 45 years) to determine if these polyps had any distinctive diagnostic radiologic features. The IFPs were located in the stomach (n = 16), small bowel (n = 13), and colon (n = 4). The lesions originated in the submucosa and were composed of fibroblasts, inflammatory cells, and a network of blood vessels. Gastric IFPs were most often located in the antrum and were usually ulcerated. Most of the patients presented with clinical evidence of gastrointestinal blood loss. Small bowel polyps were usually located in the ileum, and patients were typically older women with intestinal obstruction due to intussusception. Most of the lesions appeared as large, intramural masses at radiologic examination. Some of the lesions were pedunculated, and all were solitary. There were no distinctive features to differentiate IFPs from other mural or intraluminal lesions of the gastrointestinal tract.

Previous imaging reports of peritoneal mesothelioma have described a variety of radiologic appearances, but have not included its pathologic classification. We retrospectively reviewed 10 cases of peritoneal mesothelioma representing the following histologic categories: 7 epithelial, 2 sarcomatoid, and one biphasic. By imaging, epithelial mesotheliomas demonstrated diffuse thickening of the peritoneum and mesentery and/or multiple small nodules. The sarcomatoid-type appeared as a mass and the biphasic-type had radiologic and gross pathologic features of both sarcomatoid and epithelial types. We conclude that peritoneal mesothelioma presents with a wide spectrum of radiographic appearances and should therefore be included in the differential diagnoses of diffuse as well as localized peritoneal processes.

The polypoid manifestations of the idiopathic inflammatory bowel diseases (ulcerative colitis and Crohn disease) are often confusing. Inflammatory polyps project above the level of the surrounding mucosa. Pseudopolyposis (in ulcerative colitis) or a cobblestone appearance (in Crohn disease) results when extensive ulceration develops and only scattered islands of relatively normal mucosa remain; thus, the ulcerated areas may be falsely perceived as the baseline and the islands as polyps. Postinflammatory (filiform) polyps--fingerlike projections of submucosa covered by mucosa on all sides--reflect healing of undermined mucosal and submucosal remnants and ulcers and are almost always multiple. Patients with ulcerative colitis or Crohn disease are at increased risk for developing adenocarcinoma. Occasionally, dysplasia occurs as a polypoid lesion. Dysplasia of the colon (mucosal atypia) is a histologic marker highly associated with adenocarcinoma. Because differentiating adenocarcinoma and dysplasia from inflammatory or postinflammatory polyps is sometimes difficult or impossible, endoscopy and biopsy are usually recommended for definitive diagnosis of suspicious lesions.

The classic prototypes of the gastrointestinal polyposis syndromes are familial polyposis coli and Gardner syndrome. Extracolonic manifestations have been described in both diseases, and the distinction between them has become less clear. In fact, some authorities have suggested that familial polyposis coli and Gardner syndrome may represent a spectrum of the same disease. In both conditions, extracolonic expressions are the rule rather than the exception, and familiarity with them is essential for accurate diagnosis and correct patient management. In this pictorial essay, we discuss familial polyposis coli and Gardner syndrome together under the heading familial adenomatous polyposis syndromes. The colonic characteristics of these syndromes will be reviewed briefly, followed by examples of the most common extracolonic manifestations.

Carcinoids are tumors of the diffuse endocrine system. They occur most frequently in the gastrointestinal tract. Although they are considered malignant, their biologic behavior varies. The radiologic and pathologic appearances of gastric, duodenal, ileal, appendiceal, and rectal carcinoids are presented.

This study was designed to determine the prevalence of colorectal neoplasia in healthy, asymptomatic adults with an age-related risk for colorectal neoplasia. Ninety patients were studied with air contrast barium enema and colonoscopy. The study population included 61 males and 21 females, with an age range of 51-82 yr (65 +/- 2 yr). Adenomatous polyps were found in 27% of males and 14% of females or 24% of patients overall. Sixty-six percent of these neoplasms were above the rectosigmoid junction and the mean size of the polyps was 6.5 +/- 1.2 mm. In two patients, carcinoma was discovered. A linear association between age and the prevalence of colonic neoplasia was not demonstrated. This study demonstrates a relatively high prevalence of colonic neoplasia in patients with an age-related risk.

Malignant germ cell tumors are the most common malignant ovarian neoplasms in girls and young women. The most well known of these neoplasms are dysgerminoma, immature teratoma, endodermal sinus tumor, and a mixture of two or more of these elements. All malignant germ cell tumors, especially immature teratoma, can be associated with mature (benign) teratoma. These tumors are generally large and have a complex but predominantly solid appearance on cross-sectional images. Elevated serum alpha-fetoprotein and human chorionic gonadotropin levels can help establish the diagnosis. Cystic areas of calcifications suggestive of mature teratoma do not exclude a co-existing malignant neoplasm.

The encapsulated form of hepatocellular carcinoma (HCC) is a pathologic subtype that has been found to occur with variable frequency in typical HCC in Japanese radiological, surgical, and autopsy series. It is well-differentiated tumor that tends to grow slowly and noninvasively, and has a better prognosis than other gross forms of HCC. Among the 73 cases of typical HCC in patients of non-Asian extraction in our files, 11 could be positively identified as encapsulated based on strict pathological criteria. The purpose of this study was to review the radiographic appearance of these encapsulated tumors. Radiographically, the tumors demonstrated a hyperdense rim in 5 of 9 cases with postinfusion computed tomography scans, an anechoic halo in 4 of 6 cases with ultrasonograms, and an avascular rim on the capillary phase in 5 of the 8 cases with angiograms. Encapsulated HCC can be found in non-Asian patients, and the radiographic and pathologic findings are similar to the descriptions in the Japanese series.

Microcystic adenoma is a benign pancreatic neoplasm typically seen in elderly women. Presenting symptoms and signs such as pain, weight loss, jaundice, and a palpable mass are usually observed, but the lesion may be incidental and does not necessarily require excision. The tumor is generally large and well demarcated. It contains innumerable small cysts, giving it a honeycombed appearance. On computed tomographic scans, the hypervascular tumor has attenuation values close to those of water before contrast material is administered, but it usually enhances afterward. On sonograms, it is often predominantly echogenic, although some larger cysts may be seen. A calcified central scar may be seen with either modality.

A case of mycosis fungoides with diffuse cutaneous uptake of Ga-67 citrate is presented, and the possible causes of this uptake are discussed.

Cystic mesothelioma (CM) of the peritoneum is a rare, benign neoplasm that occurs predominantly in women and tends to recur locally. It has received little attention (to our knowledge, a single case report) in the radiology literature. Five cases of CM are presented. Computed tomography (CT) was performed in three cases, ultrasound (US) in four cases, and magnetic resonance (MR) imaging in one case. Twenty-eight cases reported in the literature are reviewed for comparison. CM shows a clear predilection for the surfaces of the pelvic viscera but is seen in other areas of the peritoneum and retroperitoneum. The neoplasm was intraperitoneal in three cases and primarily retroperitoneal in the other two cases. In all CT and US studies performed, a single large, multilocular cystic mass was demonstrated. MR imaging, performed in one case, showed that the lesion had signal characteristics typical of a watery collection low in solute concentration. It is concluded that CM of the peritoneum has a nonspecific multilocular cystic appearance on images, which does not permit it to be differentiated from other cystic lesions.

To better understand how the internal composition of ovarian teratomas influences their sonographic features, we compared their sonographic and CT appearances in 23 cases. Sixteen lesions had a mixed echo texture, with hypoechoic as well as echogenic components; two were anechoic and five were entirely echogenic. Correlation with the CT images showed that the fat present in most teratomas had variable sonographic appearances. Pure sebum was anechoic or hypoechoic, but fat intermixed with hair strands was echogenic and often attenuated the sound beam because of the numerous tissue interfaces created within the mass. The hypoechoic component of the teratoma corresponded, on CT, to low-attenuation fat in 12 tumors and to fluid in five. Most teratomas contained a dermoid plug, a protuberance arising from the tumor wall and containing hair follicles and often fragments of bone or teeth. On sonography, all dermoid plugs were seen as an echogenic mass, often associated with distal acoustic shadowing and protruding into the hypoechoic portion of the teratoma. When the dermoid plug was large and occupied most of the tumor, the entire teratoma appeared echogenic, with no discernible anechoic component. We found that three factors greatly affected the sonographic appearance of ovarian teratomas: the size of the dermoid plug, the presence and location of calcified elements, and the histologic composition of the fatty component.

The scintigraphic appearances of 12 surgically proven cases of choledochal cyst were retrospectively reviewed. In seven of 12 cases, radionuclide accumulated in the choledochal cyst (i.e., the dilated common bile duct) in less than 1 hr. In three additional cases, delayed accumulation (1-24 hr) within the cyst was seen. In two of the 12 cases, no ductal activity appeared and the diagnosis of choledochal cyst could not be made, although in one of these two cases delayed images were not obtained. Other frequent findings included delayed or nonvisualization of the gallbladder (11 of 12) and the appearance of prominent intrahepatic ducts (five of 12). We conclude that hepatobiliary scintigraphy is a noninvasive test useful in the diagnosis of choledochal cyst.

This paper is an overview of the imaging characteristics of primary carcinoma of the gallbladder, based on the premise that more general knowledge of the imaging patterns of the primary tumor and its modes of spread might increase the likelihood of accurate preoperative diagnosis of this lesion. Primary tumor patterns discussed and illustrated are: (I) an intraluminal mass, (II) focal or diffuse thickening of the gallbladder wall, and (III) replacement of the gallbladder by a mass. Illustrated patterns of tumor spread include direct extension and lymphatic and hematogenous metastases.

Seventeen proved cases of intrahepatic cholangiocarcinoma (ICAC) were reviewed to establish a radiologic-pathologic correlation. The most common appearance of ICAC at computed tomography (CT) is that of a single, homogeneous low-attenuation mass. Multiple low-attenuation lesions were present in four cases. Calcification was depicted by CT in three cases. At angiography, ICAC has a variable appearance with avascular, hypovascular, and hypervascular patterns possible. Portal obstruction was seen in only one case. The most common appearance of ICAC at sonography is that of a homogeneously hyperechoic mass, either single or multiple. In only one case was ICAC hypoechoic. Plain abdominal radiography demonstrated calcification in three patients and evidence of Thorotrast (thorium dioxide) deposition in one. Upper gastrointestinal series demonstrated abnormal gastric folds in two cases, corresponding to gastric invasion by ICAC. There were no characteristic radiographic findings, but the following features may be helpful in differentiating ICAC from other primary intrahepatic tumors, particularly typical hepatocellular carcinoma: a homogeneously echogenic or high-attenuation appearance on images that reflects the uniform nature observed at pathologic examination, the presence of calcification, and the uncommon invasion of portal or hepatic veins. Conversely, the presence of satellite lesions may blur the the distinction between ICAC and metastatic liver disease.