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Hepatocellular carcinoma (HCC) is a malignancy with variable biologic aggressiveness based on the tumor grade, presence or absence of vascular invasion, and pathologic and molecular classification. Knowledge and understanding of the prognostic implications of different pathologic and molecular phenotypes of HCC are emerging, with therapeutics that promise to provide improved outcomes in what otherwise remains a lethal cancer. Imaging has a central role in diagnosis of HCC. However, to date, the imaging algorithms do not incorporate prognostic features or subclassification of HCC according to its biologic aggressiveness. Emerging data suggest that some imaging features and further radiologic, pathologic, or radiologic-molecular phenotypes may allow prediction of the prognosis of patients with HCC. An invited commentary by Bashir is available online. Online supplemental material is available for this article. ^©RSNA, 2021.

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In the background of chronic liver disease, hepatocellular carcinoma develops via a complex, multistep process called hepatocarcinogenesis. This article reviews the causes contributing to the process. Emphasis is made on the imaging manifestations of the pathologic changes seen at many stages of hepatocarcinogenesis, from regenerative nodules to dysplastic nodules and then to hepatocellular carcinoma.

INTRODUCTION/BACKGROUND:Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 virus, is a predominantly respiratory tract infection with the capacity to affect multiple organ systems. Abnormal liver tests, mainly transaminase elevations, have been reported in hospitalized patients. We describe a syndrome of cholangiopathy in patients recovering from severe COVID-19 characterized by marked elevation in serum alkaline phosphatase (ALP) accompanied by evidence of bile duct injury on imaging. METHODS:We conducted a retrospective study of COVID-19 patients admitted to our institution from March 1, 2020, to August 15, 2020, on whom the hepatology service was consulted for abnormal liver tests. Bile duct injury was identified by abnormal liver tests with serum ALP > 3x upper limit of normal and abnormal findings on magnetic resonance cholangiopacreatography. Clinical, laboratory, radiological, and histological findings were recorded in a Research Electronic Data Capture database. RESULTS:Twelve patients were identified, 11 men and 1 woman, with a mean age of 58 years. Mean time from COVID-19 diagnosis to diagnosis of cholangiopathy was 118 days. Peak median serum alanine aminotransferase was 661 U/L and peak median serum ALP was 1855 U/L. Marked elevations of erythrocyte sedimentation rate, C-reactive protein, and D-dimers were common. Magnetic resonance cholangiopacreatography findings included beading of intrahepatic ducts (11/12, 92%), bile duct wall thickening with enhancement (7/12, 58%), and peribiliary diffusion high signal (10/12, 83%). Liver biopsy in 4 patients showed acute and/or chronic large duct obstruction without clear bile duct loss. Progressive biliary tract damage has been demonstrated radiographically. Five patients were referred for consideration of liver transplantation after experiencing persistent jaundice, hepatic insufficiency, and/or recurrent bacterial cholangitis. One patient underwent successful living donor liver transplantation. DISCUSSION/CONCLUSIONS:Cholangiopathy is a late complication of severe COVID-19 with the potential for progressive biliary injury and liver failure. Further studies are required to understand pathogenesis, natural history, and therapeutic interventions.

Bodies have continuous reticular networks, comprising collagens, elastin, glycosaminoglycans, and other extracellular matrix components, through all tissues and organs. Fibrous coverings of nerves and blood vessels create structural continuity beyond organ boundaries. We recently validated fluid flow through human fibrous tissues, though whether these interstitial spaces are continuous through the body or discontinuous, confined within individual organs, remains unclear. Here we show evidence for continuity of interstitial spaces using two approaches. Non-biological particles (tattoo pigment, colloidal silver) were tracked within colon and skin interstitial spaces and into adjacent fascia. Hyaluronic acid, a macromolecular component of interstitial spaces, was also visualized. Both techniques demonstrate interstitial continuity within and between organs including within perineurium and vascular adventitia traversing organs and the spaces between them. We suggest that there is a body-wide network of fluid-filled interstitial spaces that has significant implications for molecular signaling, cell trafficking, and the spread of malignant and infectious disease.

Background: Digestive symptoms are often seen in COVID-19 patients with poor outcomes. The Viral RNA is mostly positive in the stool of these patients, and has a longer delay before viral clearance. However, its diagnostic value and significance for guiding clinical treatment remain unknown. And the pathologic alterations in the GI tract in COVID-19 patients have not been well defined. We evaluated rectal swab SAS-CoV-2 test and histopathologic changes in the small intestine in autopsy patients.
Design(s): 18 autopsy cases with confirmed SAS-CoV2 infection were included. Nasal, bronchial, and rectal swab SARS-CoV-2 PCR were performed at the time of autopsy. Clinical information included demographics, comorbidities, presenting symptoms, related laboratory tests were collected. Histopathologic evaluation was performed and correlated with clinical properties.
Result(s): 83% (15/18) of patients were male. Median age is 50 years. 7/18 (38.9%) patients had diarrhea in addition to cough, fever and other symptoms. Except in one case, all patients had underlying comorbidities of diabetes, hypertension and /or obesity. In the small intestine, acute inflammation was not seen in any cases. 5/18 displayed mild and one showed moderate chronic inflammation. Hypermucinous change was found in six patients but not associated with diarrhea. 3 cases had microthrombi identified in the sections. Notably, obviously increased D dimer in lab tests were noticed in all patients. Postmortem 17/17 (100%) nasal, 18/18 (100%) bronchial and 7/16 (43.8%) rectal swabs showed SARS-CoV-2 PCR positivity. 3 of 7 (42.9%) patients with diarrhea are positive in rectal swab for SARS-CoV-2.
Conclusion(s): There are no specific COVID-19 changes in the small intestine. More investigations are needed, especially on tissues from different locations of the GI tract. Data from rectal swab testing suggests that it is not ideal for diagnosing COVID-19, guiding treatment, or predicting small intestinal pathology

Background: In addition to respiratory distress, GI symptoms have been reported in COVID-19 patients at various stages of the disease. Among the GI symptoms that have been reported, diarrhea, nausea, vomiting, abdominal pain and GI bleeding were often seen. Age and comorbid conditions such as obesity, HTN, DM and/or CAD have been considered as risk factors for COVID-19 patients for severe disease. GI manifestations in COVID-19 patients appeared to act as a sign for a serious condition. The virus has been identified in the stool and in rectal swabs of some infected patients, even after a negative nasopharyngeal test. There is a lack of reports on pathological alterations of the GI tract in COVID-19 infected patients.
Design(s): 16 PCR confirmed COVID-19 patients (11 males and 5 females) were included in the study. Biopsy or resection specimens were taken from the esophagus (4), stomach (6), small intestine (5), appendix (3), colon (5) and gallbladder (3). Clinical information including demographics, comorbidities, GI symptoms, related laboratory tests were collected. Histopathologic evaluation was performed and correlated with clinical properties.
Result(s): The age of the patients ranged from 10 to 84 years old, with an average of 47 years. Eight (50%) patients had at least one comorbid condition, two patients (12.5%) had prior history of cancer, and six patients had no significant medical history. Abdominal pain and GI bleeding were the most common presenting symptoms. Histologically, acute and chronic inflammation was seen in 14 of 16, and 15 of 16 cases, respectively. Eight cases showed severe acute inflammation with ulceration. The mucosal changes included nonspecific reactive change, hypermucinous, atrophic/ischemic changes, and necrosis, were indiscriminately noticed in these cases. Four cases showed intraepithelial lymphocytosis. Viral like inclusions were found in four cases. Microthrombi were identified in 5 cases with an average patient age of 60 years. Notably, microthrombi were seen in about 5 out of 8 (62%) patients with comorbidities. The patients with microthrombi had a higher D dimer test value than those without thrombus. Three patients died shortly after operation, and two of them showed microthrombi in the tissue specimens.
Conclusion(s): Acute and chronic inflammation were indiscriminately seen in these cases. Microthrombi were dominantly found in aging patients with comorbidities, suggesting microthrombi in the GI tract may be a histologic indication for severe COVID-19 patients with GI symptoms

Gastrointestinal (GI) symptoms of SARS-CoV-2/COVID-19 in the form of anorexia, nausea, vomiting, abdominal pain and diarrhea are usually preceded by respiratory manifestations and are associated with a poor prognosis. Hematochezia is an uncommon clinical presentation of COVID-19, and we hypothesize that older patients with significant comorbidities (obesity and cardiovascular) and prolonged hospitalization are susceptible to ischemic injury to the bowel. We reviewed the clinical course, key laboratory data including acute-phase reactants, and drug/medication history in 2 elderly male patients admitted for COVID-19 respiratory failure. Both patients had a complicated clinical course and suffered from hematochezia, acute blood loss, and anemia which led to hemodynamic instability requiring blood transfusion around day 40 of their hospitalization. Colonoscopic impressions were correlated with the histopathological findings in the colonic biopsies that included changes compatible with ischemia and nonspecific acute inflammation, edema, and increased eosinophils in the lamina propria. Both patients were hemodynamically stable, on prophylactic anticoagulants, multiple antibiotics, and antifungal agents due to respiratory infections at the time of lower GI bleeding. Hematochezia resolved spontaneously with supportive care. Both patients eventually recovered and were discharged. Elderly patients with significant comorbid conditions are uniquely at risk for ischemic injury to the bowel. This case report highlights hematochezia as an uncommon GI manifestation of spectrum of COVID-19 complications. The causes of bleeding in these COVID-19 associated cases are likely multifactorial and can be attributed to concomitant etiologies based on their age, multiple comorbid conditions, prolonged hospitalization compounded by lung injury, and hypoxia precipitated by the virus. We hypothesize that rather than a direct viral cytopathic effect, ischemia and hypoperfusion may be unleashed due to the cytokine storm orchestrated by the virus that leads to abnormal coagulation profile. Additional factors that may contribute to ischemic injury are prophylactic use of anticoagulants and polypharmacy. There were no other causes to explain the brisk lower GI bleeding. Presentation of hematochezia was followed by hemodynamic instability that may further increase the mortality and morbidity of COVID-19 patients, and prompt consultation and management by gastroenterology is therefore warranted.

The human brain functions at the center of a network of systems aimed at providing a structural and immunological layer of protection. The cerebrospinal fluid (CSF) maintains a physiological homeostasis that is of paramount importance to proper neurological activity. CSF is largely produced in the choroid plexus where it is continuous with the brain extracellular fluid and circulates through the ventricles. CSF movement through the central nervous system has been extensively explored. Across numerous animal species, the involvement of various drainage pathways in CSF, including arachnoid granulations, cranial nerves, perivascular pathways, and meningeal lymphatics, has been studied. Among these, there is a proposed CSF clearance route spanning the olfactory nerve and exiting the brain at the cribriform plate and entering lymphatics. While this pathway has been demonstrated in multiple animal species, evidence of a similar CSF egress mechanism involving the nasal cavity in humans remains poorly consolidated. This review will synthesize contemporary evidence surrounding CSF clearance at the nose-brain interface, examining across species this anatomical pathway, and its possible significance to human neurodegenerative disease. Our discussion of a bidirectional nasal pathway includes examination of the immune surveillance in the olfactory region protecting the brain. Overall, we expect that an expanded discussion of the brain-nose pathway and interactions with the environment will contribute to an improved understanding of neurodegenerative and infectious diseases, and potentially to novel prevention and treatment considerations.