"Periportal neoplasms"--a CT perspective: review article

Hypoattenuating periportal halo on CT in a patient population can occur in presence of a variety of diseases

Many pathologies can occur in the periportal space and manifest as fluid accumulation, visible in Computed tomography (CT) images as a circumferential region of low attenuation around the intrahepatic portal vessels, called periportal halo (PPH). This finding is associated with different types of hepatic and extra-hepatic disease in humans and remains a non-specific sign of unknown significance in veterinary literature. The aim of this study was to investigate the prevalence of PPH in a population of patients undergoing CT examination and to assess the presence of lesions related to hepatic and extra-hepatic disease in presence of PPH. CT studies including the cranial abdomen of dogs and cats performed over a 5-year period were retrospectively reviewed. The prevalence of PPH was 15% in dogs and 1% in cats. 143 animals were included and the halo was classified as mild, moderate and severe, respectively in 51%, 34% and 15% of animals. The halo distribution was generalized in 79 cases, localized along the second generation of portal branches in 63, and along the first generation only in one. Hepatic disease was present in 58/143 and extra-hepatic disease in 110/143 of the cases. Main cause of hepatic (36%) and extra-hepatic disease (68%) was neoplasia. Associations between halo grades and neoplasia revealed to be not statistically significant (p = 0.057). In 7% of animals the CT examination was otherwise unremarkable. PPH is a non-specific finding, occurring in presence of a variety of diseases in the examined patient population.

Extramedullary haematopoiesis presenting as a periportal mass

Extramedullary haematopoiesis (EMH) is defined as haematopoiesis occurring in organs outside the bone marrow. The liver is one of the rare sites of EMH, and to the best of our knowledge, a few cases of adult EMH of the liver have been reported in the last 20 years. Here, we reported the case of a 68-year-old man with a known history of myelofibrosis presented with vague abdominal pain. An abdominal CT scan showed a hypoattenuating periportal mass encasing the portal vein. The final diagnosis of EMH was made through the histopathological examination. This is a rare presentation of EMH, which may be easily mistaken for other pathologies such as metastases. Familiarity with this type of presentation aids in correctly diagnosing it in an appropriate clinical setting.

Imaging of pathology involving the space around the hepatic veins: "perivenous pattern"

We aimed to illustrate diseases involving the potential space around the hepatic veins. Perivenous halo sign can be seen in patients with congestive heart failure or fluid overload. Perivenous involvement can be observed in patients with alcoholic fatty liver disease, which can be focal or diffuse. Metastasis and primary liver tumor spread can also involve this space most likely due to involvement of lymphatics around hepatic veins.