BackgroundErdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis with characteristic radiological and histological features. This entity is defined by a mononuclear infiltrate consisting of lipid-laden, foamy histiocytes that stain positively for CD68 and negatively for CD1a. Osseous involvement is constant and characteristic. Extra-osseous lesions may affect the retroperitoneum, lungs, skin, heart, brain and orbits.MethodsBoth radiography and technetium-99m bone scintigraphy may reveal osteosclerosis of the long bones, which is a typical finding in ECD. For visceral involvement, computed tomography (CT) is most useful, while magnetic resonance (MR) imaging is more sensitive for cardiovascular lesions; 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/CT scanning is useful in assessing the extension of ECD lesions.ResultsThe prognosis is extremely variable and is often worse when there is cardiovascular system involvement. Diagnosis is based on the combination of radiographic, CT, MR imaging and nuclear medicine features and a nearly pathognomonic immunohistochemical profile.ConclusionThe aims of this work are to perform a systematic review of Erdheim-Chester disease as seen on imaging of the chest, abdomen and musculoskeletal system and to discuss the diagnostic workup and differential diagnoses according to the imaging presentation.Teaching points• Bone involvement is usually present in patients, and the imaging findings are pathognomonic of ECD.• The circumferential periaortic infiltration may extend to its branches, sometimes becoming symptomatic.• Cardiac involvement—the pericardium, right atrium and auriculoventricular sulcus—worsens its prognosis.• Perirenal infiltration extending to the proximal ureter is highly suggestive of this disease.

Purpose:To evaluate the diagnostic performance of imaging features of gadoxetic acid-enhanced magnetic resonance (MR) imaging to differentiate among hepatocellular adenoma (HCA) subtypes by using the histopathologic results of the new immunophenotype and genotype classification and to correlate the enhancement pattern on the hepatobiliary phase (HBP) with the degrees of expression of organic anion transporting polypeptide (OATP1B1/3), multidrug resistance-associated protein 2 (MRP) (MRP2), and MRP 3 (MRP3) transporters. Materials and Methods:This retrospective study was approved by the institutional review board, and the requirement for informed consent waived. MR imaging findings of 29 patients with 43 HCAs were assessed by two radiologists independently then compared with the histopathologic analysis as the standard of reference. Receiver operating characteristic curves and Spearman rank correlation coefficient were used to test the diagnostic performance of gadoxetic acid-enhanced MR imaging features, which included the retention or washout at HBP and degree of transporter expression. Interreader agreement was assessed by using the k statistic with 95% confidence interval. Results:The area under the curve for the diagnosis of inflammatory HCA was 0.79 (95% confidence interval: 0.64, 0.90); for the steatotic type, it was 0.90 (95% confidence interval: 0.77, 0.97); and for the b-catenin type, it was 0.87 (95% confidence interval: 0.74, 0.95). There were no imaging features that showed a significant statistical correlation for the diagnosis of unclassified HCAs. On immunohistochemical staining, OATP1B1/3 expression was the main determinant for the retention, whereas MRP3 was the key determinant for washout of gadoxetic acid at HBP (P , .001). MRP2 appeared to have no role. Conclusion:Gadoxetic acid-enhanced MR imaging features may suggest the subtype of HCA. The degree of OATP1B1/3 and MRP3 expression correlated statistically with gadoxetic acid retention and washout, respectively, in the HBP.q RSNA, 2015

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Lung cancer has a known relationship with smoking and is one of the leading causes of cancer-related death worldwide. Although the number of studies discussing lung cancer is vast, treatment efficacy is still suboptimal due to the wide range of factors that affect patient outcome. This review aims to collect information on lung cancer treatment, specially focused on radiation therapy. It also compiles information regarding the influence of radiotherapy on the immune system and its response to tumour cells. It evaluates how immune cells react after radiation exposure and the influence of their cytokines in the tumour microenvironment. The literature analysis points out that the immune system is a very promising field of investigation regarding prognosis, mostly because the stromal microenvironment in the tumour can provide some information about what can succeed in the future concerning treatment choices and perspectives. T cells (CD4+ and CD8+), interleukin-8, vascular endothelial growth factor and transforming growth factor-β seem to have a key role in the immune response after radiation exposure. The lack of large scale studies means there is no common consensus in the scientific community about the role of the immune system in lung cancer patients treated with radiotherapy. Clarification of the mechanism behind the immune response after radiation can lead to better treatments and better quality life for patients.

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A 61-year-old male presented to the hospital with a 5-day history of epigastric pain, vomiting and regurgitation. The physical examination was positive only for upper abdominal tenderness. Laboratory findings were unremarkable.Ultrasound examination was negative for gallstones or biliary dilatation. Abdominal contrast-enhanced CT showed a rimenhancing cystic structure (mean internal density: 13 HU) (Fig. A, arrowhead) lateral to the lumen of the descending duodenum, which was narrowed and internally displaced (Fig. A, arrow). During hospitalization the patient's clinical status deteriorated, with worsening of abdominal pain, which granted repetition of the CT. This showed that the peri-duodenal cystic lesion had significantly increased in size, and the contents were now high-attenuating (mean internal density: unenhanced scan -66 HU, contrastenhanced scan -71 HU), in keeping with intra-lesional hemorrhage (Fig. B, asterisk).The lesion was surgically excised. The histopathological study was consistent with a duodenal duplication cyst complicated with hemorrhage due to the presence of ectopic gastric mucosa. CommentDuodenal duplication cysts represent 4-5% of duplications in the gastrointestinal tract, and are thought to develop due to incomplete recanalization of the foregut during embryological development. They usually arise in the medial wall of the second and third portions of the duodenum, and typically do not communicate with the duodenal lumen. The cyst is generally lined by duodenal mucosa, but gastric mucosa and pancreatic tissue may be present in up to 15% of cases.Most duplication cysts manifest during the first year of life with symptoms of bowel obstruction. They seldom are symptomatic in adulthood, and are usually found incidentally at endoscopy or imaging performed for other reasons. However, they may be clinically silent for many years, and present in the adult usually with symptoms of obstruction or a palpable abdominal mass. If heterotopic gastric mucosa is present in the cyst wall, ulceration may occur, and the cyst may present with bleeding or perforation. Jaundice can occur due to biliary obstruction. Infected duodenal duplication cysts and pancreatitis due to compression or communication with the pancreatic duct have also been described. Rarely, carcinoma may develop inside a duplication cyst.On ultrasound, the lesion is hypo/anechoic and the wall of the cyst has a characteristic bowel wall appearance consisting of an echogenic inner mucosa surrounded by a thin hypoechoic halo of muscular layer; peristaltic waves through the cyst may also be seen. At CT, it usually manifests as a well-circumscribed fluid-filled structure with a thick slightly enhancing wall. Areas of high attenuation within the cyst may be evident, resulting from hemorrhage or proteinaceous material. Pancreatic ductal dilatation due to obstruction may also be noted. Infection may be suspected when the cyst shows a thick enhancing wall or septa and surrounding inflammatory changes. The presence of enhancing solid vegetation ...

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