Lipopeliosis. An immunohistochemical and clinicopathologic study of five cases

Sequential Protocol Biopsies Post-Liver Transplant From Donors With Moderate Macrosteatosis: What Happens to the Fat?

The number of steatotic deceased donor livers encountered has continued to rise as a result of the obesity epidemic. Little is known about the histological characteristics of moderately macrosteatotic livers over time in the recipient following liver transplantation (LT). All recipients undergoing LT at Mayo Clinic Florida with donor livers with moderate macrosteatosis (30%-60%) from 2000-2017 were identified (n = 96). Routine protocol liver biopsies were performed 1-week and 6-months following LT. All liver donor and protocol biopsies were read by an experienced liver pathologist. Of the 96 moderate macrosteatosis LTs, 70 recipients had post-LT protocol liver biopsies available and comprised the study cohort. Median donor allograft macrosteatosis at the time of transplant was 33% (IQR, 30%-40%) compared with 0% (IQR, 0%-2%) at 1-week (P < 0.001) and 0% (IQR, 0%-0%) at 6-months (P < 0.001) following LT. Biopsies at 1-week post-LT displayed pericentral necrosis in 57.1% of recipients and lipopeliosis in 34.3% of recipients. In the 6-month post-LT biopsies, cholestasis was seen in 3 (4.3%) of the recipients, whereas grade 2 fibrosis was seen in 6 recipients (8.6%). Graft survival at 5 years in the present cohort was 74.0%. Moderate macrosteatosis (30%-60%) in the donor allograft demonstrates complete reversal on liver biopsies performed as early as 7 days following LT and remains absent at 6-months following LT. Both pericentral necrosis and lipopeliosis are common features on day 7 biopsies. Despite these encouraging findings, the perioperative risks of using these livers (postreperfusion cardiac arrest and primary nonfunction) should not be understated. Long-term graft survival is acceptable in patients who are able to overcome the immediate perioperative risk of using moderately steatotic donor livers.

Acute Kidney Injury Patterns Following Transplantation of Steatotic Liver Allografts

Background: Steatotic grafts are increasingly being used for liver transplant (LT); however, the impact of graft steatosis on renal function has not been well described. Methods: A total of 511 allografts from Mayo Clinic Arizona and Minnesota were assessed. We evaluated post-LT acute kidney injury (AKI) patterns, perioperative variables and one-year outcomes for patients receiving moderately steatotic allografts (>30% macrovesicular steatosis, n = 40) and compared them to non-steatotic graft recipients. Results: Post-LT AKI occurred in 52.5% of steatotic graft recipients versus 16.7% in non-steatotic recipients (p < 0.001). Ten percent of steatotic graft recipients required new dialysis post-LT (p = 0.003). At five years, there were no differences for AKI vs. no AKI patient survival (HR 0.95, 95% CI 0.08–10.6, p = 0.95) or allograft survival (HR 1.73, 95% CI 0.23–13.23, p = 0.59) for those using steatotic grafts. Lipopeliosis on biopsy was common in those who developed AKI (61.0% vs. 31.6%, p = 0.04), particularly when the Model for End-Stage Liver Disease (MELD) was ≥20 (88.9%; p = 0.04). Lipopeliosis was a predictor of post-LT AKI (OR 6.0, 95% CI 1.1–34.6, p = 0.04). Conclusion: One-year outcomes for moderately steatotic grafts are satisfactory; however, a higher percentage of post-LT AKI and initiation of dialysis can be expected. Presence of lipopeliosis on biopsy appears to be predictive of post-LT AKI.

Fatal diffuse pulmonary fat microemboli following reperfusion in liver transplantation with the use of marginal steatotic allografts

Organ shortage is a major cause of delayed liver transplantation and increased waitlist time. The level of donor steatosis is a significant determinant in organ selection. Scarcity of organs has led some programs to expand their acceptable criteria for the percentage of steatosis. We report two cases of liver transplantation of steatotic donor organs that resulted in mortality within hours from transplantation. Postmortem analysis showed evidence of diffuse pulmonary fat microemboli likely originating from the donor organ, with marked preservation reperfusion injury. The mechanism of diffuse fat microemboli in this setting and possible relationship to other perioperative syndromes (transfusion-related lung injury, acute kidney injury, and postreperfusion syndrome) is discussed.

Mechanisms of liver involvement in systemic disease

The liver may be injured during the course of many systemic diseases. The mechanisms of injury can be broadly divided into four pathways: vascular, toxic, immune, and hormonal. Vascular obstruction may be an early event but is also the late common pathway from all mechanisms. Despite the large number of possible initiating factors, the end results are few, including death of hepatocytes or cholangiocytes, leading to the stereotyped syndromes of acute liver failure, non-cirrhotic portal hypertension, or cirrhosis. This small number of outcomes is a reflection of the few anatomic patterns that can be generated by microvascular obstruction. Vascular obstruction may occur by thrombosis, inflammation, or congestive injury. The innate immunity pathway is activated by endotoxin and other agents, leading to inflammatory infiltration, release of cytokines and reactive oxygen species, and necrosis. The adaptive immune pathway involves the generation of antibodies and antigen-specific cell-mediated attack on hepatic cells. Hormonal effects are principally involved when overnutrition leads to hyperinsulinemia followed by hepatocellular necrosis.

Fat-containing lesions of the liver: cross-sectional imaging findings with emphasis on MRI

OBJECTIVE

The purpose of this pictorial essay is to identify different types of liver lesions that contain fat. Cross-sectional imaging findings of fat- or lipid-containing lesions can help in characterizing focal liver lesions. We searched our archive retrospectively and reviewed the literature for fat-containing liver lesions and identified 16 different types.

CONCLUSION

These lesions can contain macroscopic fat (i.e., angiomyolipoma, lipoma, liposarcoma, hydatid cyst, lipopeliosis, adrenal rest tumor, pseudolipoma, hepatic teratoma, pericaval fat, extramedullary hematopoiesis, and metastases) or intracellular lipid (i.e., focal steatosis, adenoma, focal nodular hyperplasia, regenerative nodules, and hepatocellular carcinoma). CT, MRI, and sonographic findings of these lesions can help in characterization by allowing specific diagnosis or narrowing the differential diagnosis of liver lesions.

Hepatic steatosis and its relationship to transplantation

Fatty infiltration of the liver is common in the brain-dead donor population and has a strong correlation with primary nonfunction after cold preservation, a condition that is catastrophic to liver transplant recipients. This literature review examines factors associated with the development, diagnosis, quantification, and clinical management of this difficult condition.