Metabolic Toxification of 1,2-Unsaturated Pyrrolizidine Alkaloids Causes Human Hepatic Sinusoidal Obstruction Syndrome: The Update.

Saturated and unsaturated pyrrolizidine alkaloids (PAs) are present in more than 6000 plant species growing in countries all over the world. They have a typical heterocyclic structure in common, but differ in their potential toxicity, depending on the presence or absence of a double bond between C1 and C2. Fortunately, most plants contain saturated PAs without this double bond and are therefore not toxic for consumption by humans or animals. In a minority of plants, however, PAs with this double bond between C1 and C2 exhibit strong hepatotoxic, genotoxic, cytotoxic, neurotoxic, and tumorigenic potentials. If consumed in error and in large emouns, plants with 1,2-unsaturated PAs induce metabolic breaking-off of the double bonds of the unsaturated PAs, generating PA radicals that may trigger severe liver injury through a process involving microsomal P450 (CYP), with preference of its isoforms CYP 2A6, CYP 3A4, and CYP 3A5. This toxifying CYP-dependent conversion occurs primarily in the endoplasmic reticulum of the hepatocytes equivalent to the microsomal fraction. Toxified PAs injure the protein membranes of hepatocytes, and after passing their plasma membranes, more so the liver sinusoidal endothelial cells (LSECs), leading to life-threatening hepatic sinusoidal obstruction syndrome (HSOS). This injury is easily diagnosed by blood pyrrolizidine protein adducts, which are perfect diagnostic biomarkers, supporting causality evaluation using the updated RUCAM (Roussel Uclaf Causality Assessment Method). HSOS is clinically characterized by weight gain due to fluid accumulation (ascites, pleural effusion, and edema), and may lead to acute liver failure, liver transplantation, or death. In conclusion, plant-derived PAs with a double bond between C1 and C2 are potentially hepatotoxic after metabolic removal of the double bond, and may cause PA-HSOS with a potential lethal outcome, even if PA consumption is stopped.

Sinusoidal Obstruction Syndrome and Postoperative Complications Resulting from Preoperative Chemotherapy for Colorectal Cancer Liver Metastasis.

BACKGROUND/AIM: The aim of this study was to investigate the effects of preoperative chemotherapy on the healthy, metastasis-free part of the liver in colorectal cancer patients with liver metastasis, and the relationship between chemotherapy and postoperative complications. PATIENTS AND METHODS: Our study included 90 cases of colorectal cancer liver metastasis resected after preoperative chemotherapy. The patients were divided into three groups according to the received chemotherapy regimen: 20 cases received mFOLFOX6, 54 cases a combination of mFOLFOX6 with bevacizumab, and 16 cases a combination of mFOLFOX6 and cetuximab or panitumumab. RESULTS: The mean numbers of sinusoidal injuries for each chemotherapy type were compared. The group treated with the combination of mFOLFOX6 and bevacizumab showed a lower extent of sinusoidal injury relative to other groups; this intergroup difference became increasingly remarkable as the number of chemotherapy cycles increased. Complications of various extents were found in all three groups, but no significant differences were observed between the three groups. CONCLUSION: In cases where preoperative chemotherapy was extended over a long period, combined use of bevacizumab was thought to be effective because of stabilization of disturbed liver hemodynamics resulting from sinusoidal injury suppression effects, allowing effective distribution of anti-cancer agents to tumors.

Optimizing hepatic venous outflow reconstruction for hepatic vein stenosis with indwelling stent in living donor liver retransplantation.

The patient was a boy of 7 years and 5 months of age, who underwent LDLT for acute liver failure at 10 months of age. HV stent placement was performed 8 months after LDLT because of intractable HV stenosis. At 7 years of age, his liver function deteriorated due to chronic rejection. The patient therefore underwent living donor liver retransplantation from his father. The HV was transected with the stent in situ. The IVC was resected due to stenosis. The pericardial cavity was opened and detached around the IVC to elongate the IVC. The divided ends of the IVC were joined by suturing to the posterior wall of the IVC. A new triangular orifice was made by adding an incision on the anterior wall of the IVC. The graft HV was then anastomosed to the new orifice with continuous sutures in the posterior wall and interrupted sutures in the anterior wall using 5-0 non-absorbable sutures. Doppler ultrasound showed a triphasic waveform. We successfully performed HV reconstruction without a vascular graft. This is a feasible procedure for overcoming HV stenosis in LDLT patients with an indwelling stent.

Chemotherapy-induced Sinusoidal Injury (CSI) score: a novel histologic assessment of chemotherapy-related hepatic sinusoidal injury in patients with colorectal liver metastasis.

BACKGROUND: Preoperative neoadjuvant therapy for colorectal liver metastases (CRLM) is increasing in use and can lead to chemotherapy-induced damage to sinusoidal integrity, namely sinusoidal obstruction syndrome (SOS). SOS has been associated with an increased need for intraoperative blood transfusions, increased length of hospitalization post-surgery, decreased tumor response, and a shorter overall survival after resection due to liver insufficiency. It is critical for clinicians and pathologists to be aware of this type of liver injury, and for pathologists to include the status of the background, non-neoplastic liver parenchyma in their pathology reports. In this study, expression of CD34 by sinusoidal endothelial cells (SECs), increased expression of smooth muscle actin (SMA) by hepatic stellate cells (HSCs), and aberrant expression of glutamine synthetase (GS) by noncentrizonal hepatocytes were semiquantitatively evaluated in liver resection or biopsy specimens from patients with CRLM to determine their diagnostic value for assessing chemotherapy-induced sinusoidal injury (CSI). METHODS: The expression of each marker was compared among 22 patients with CRLM with histologically evident SOS (SOS+) and 8 patients with CRLM who had not undergone chemotherapy. Each case was given a histologic grade using the sinusoidal obstruction syndrome index score (SOS-I) to assess the likelihood of SOS. Cases were also given an immunohistochemical grade using the total CSI score calculated as the sum of CD34, SMA, and GS scores. RESULTS: Abnormal staining patterns for CD34 and SMA were significantly more frequent and extensive in SOS+ cases than in the controls (81.8% vs. 25%, P < 0.01; 72.7% vs. 25%, P = 0.03). Aberrant GS expression in midzonal and periportal hepatocytes was only observed in SOS+ cases (31.8% vs. 0%), but this difference did not reach statistical significance. The CSI score was significantly higher in the SOS+ cases when compared to controls (P < 0.01), and was associated with a higher SOS histologic grade (P = 0.02). CONCLUSIONS: The CSI score, calculated using an immunohistochemical panel consisting of CD34, SMA, and GS, may serve as an objective marker of chemotherapy-induced sinusoidal injury and could help diagnose this peculiar form of liver injury.

Sinusoidal obstruction syndrome in the animal model: influence on liver surgery.

PURPOSE: In recent years, multimodal treatment approaches have led to an increased median survival time of patients with colorectal liver metastases. In particular, this results from new perioperative chemotherapy regimens, which in turn are accompanied by an increased risk of perioperative bleeding and/or liver failure due to the hepatotoxic side effects. Nineteen to 58 % of patients treated with oxaliplatin develop sinusoidal obstruction syndrome (SOS). The influence of preexisting SOS on liver surgery remains controversial. METHODS: Animals were operated 4 days after SOS induction with monocrotaline and received either vascular occlusion in the form of Pringle maneuver (PM) or hepatectomy (LR; 70 %) or a combination of both (LR + PM). Postoperative liver function was assessed by determination of liver enzyme levels, bile production, and tissue oxygen saturation. RESULTS: Preexisting SOS impaired morbidity after liver resection, reflected by elevated liver enzyme levels, reduced bile secretion, and low liver tissue oxygenation levels. Mortality was increased by up to 25 %. Additional ischemia in the form of PM showed no further impact in the LR ± PM group compared to LR alone. CONCLUSION: PM without LR results in high enzyme distribution in the SOS group. SOS significantly affects the outcome after liver resection in our experimental rat model only without PM and showed no protective effect in ischemia in the form of PM.

Sequential preoperative hepatic vein embolization after portal vein embolization for extended left hepatectomy in colorectal liver metastases.

BACKGROUND: The role of portal vein embolization to increase future liver remnant (FLR) is well-established in the treatment of colorectal liver metastases. However, the role of hepatic vein embolization is unclear. CASE REPORT: A patient with colorectal liver metastases received neoadjuvant chemotherapy prior to attempted resection. At the time of resection his tumor appeared to invade the left and middle hepatic vein, requiring an extended left hepatectomy including segments five and eight. Post-operatively, he underwent sequential left portal vein embolization followed by left hepatic vein embolization and finally, middle hepatic vein embolization. Hepatic vein embolization was performed to increase the FLR as well as to allow collateral drainage of the FLR to develop. A left trisectionectomy was then performed and no evidence of postoperative liver congestion or morbidity was found. CONCLUSION: Sequential portal vein embolization and hepatic vein embolization for extended left hepatectomy may be considered to increase FLR and may prevent right hepatic congestion after sacrificing the middle vein.

Results of a stepwise approach to extrahepatic portal vein obstruction in children.

BACKGROUND: The management of extrahepatic portal vein obstruction (EHPVO) in children is controversial. We report our experience with a prospective evaluation of a stepwise protocol based on severity of portal hypertension and feasibility of mesoportal bypass (MPB). METHODS: After diagnosis, children with EHPVO underwent surveillance endoscopies and received nonselective ß-blockers (NSBBs) or endoscopic variceal obliteration (EVO) when large varices were detected. In patients who failed NSBBs and EVO, we considered MPB as first-line and shunts or transjugular intrahepatic portosystemic shunt (TIPS) as second-line options. RESULTS: Sixty-five children, median age 12.5 (range 1.6-25.8), whose age at diagnosis was 3.5 (0.2-17.5) years, were referred to our unit. Forty-three (66%) had a neonatal illness, 36 (55%) an umbilical vein catheterisation. Thirty-two (49%) presented with bleeding at a median age of 3.8 years (0.5-15.5); during an 8.4-year follow-up period (1-16), 43 (66%) had a bleeding episode, 52 (80%) were started on NSBBs, 55 (85%) required EVO, and 33 (51%) required surgery or TIPS. The Rex recessus was patent in 24 of 54 (44%), negatively affected by a history of umbilical catheterisation (P = 0.01). Thirty-four (53%) patients underwent a major procedure: MPB (13), proximal splenorenal (13), distal splenorenal (2), mesocaval shunt (3), TIPS (2), and OLT (1). At the last follow-up, 2 patients died, 53 of 57 (93%) are alive with bleeding control, 27 of 33 (82%) have a patent conduit. CONCLUSIONS: Children with EHPVO have a high rate of bleeding episodes early in life. A stepwise approach comprising of medical, endoscopic, and surgical options provided excellent survival and bleeding control in this population.

Effect of preoperative chemotherapy on postoperative liver regeneration following hepatic resection as estimated by liver volume.

BACKGROUND: In order to analyze postoperative liver regeneration following hepatic resection after chemotherapy, we retrospectively investigated the differences in liver regeneration by comparing changes of residual liver volume in three groups: a living liver donor group and two groups of patients with colorectal liver metastases who did and did not undergo preoperative chemotherapy. METHODS: This study included 32 patients who had at least segmental anatomical hepatic resection. Residual liver volume, early postoperative liver volume, and late postoperative liver volume were calculated to study the changes over time. From the histopathological analysis of chemotherapy-induced liver disorders, the effect on liver regeneration according to the histopathology of noncancerous liver tissue was also compared between the two colorectal cancer groups using Kleiner's score for steatohepatitis grading {Hepatology, 41(6):1313-1321, 2005} and sinusoidal obstruction syndrome (SOS) grading for sinusoidal obstructions {Ann Oncol, 15(3):460-466, 2004}. RESULTS: Assuming a preoperative liver volume of 100%, mean late postoperative liver volumes in the three groups (the living liver donor group and the colorectal cancer groups with or without chemotherapy) were 91.1%, 80.8%, and 81.3%, respectively, with about the same rate of liver regeneration among the three groups. Histopathological analysis revealed no correlation between either the Kleiner's scores or the SOS grading and liver regeneration. CONCLUSIONS: As estimated by liver volume, the level of liver regeneration was the same in normal livers, tumor-bearing livers, and post-chemotherapy tumor-bearing livers. Liver regeneration was not adversely affected by the extent to which steatosis or sinusoidal dilatation was induced in noncancerous tissue by chemotherapy in patients scheduled for surgery.

Three-dimensional computed tomography image based endovascular treatment for hepatic vein.

Along with the expansion of living donor liver transplantation, whereby hepatic venous anastomosis is mandatory, the frequency of hepatic venous stenosis that need interventional treatment is increasing. Due to its anatomical features, there are several pitfalls in the process of endovascular intervention for hepatic vein. Insufficient information of and around the hepatic vein may lead to miss-diagnosis of target lesion. Simulation by using three-dimensional computed tomography images was useful in planning the direction of X-ray projection and, as a consequence, contributed to safe endovascular treatment for hepatic venous stenosis.

Successful cord blood transplantation in a patient with malignant infantile osteopetrosis and hemophilia.

MIOP is a congenital disorder of osteoclast differentiation or dysfunction. Inadequate bone resorption by osteoclasts results in a spectrum of complications including hypocalcemia, osteosclerosis, marrow failure, extramedullary hematopoiesis, hydrocephalus, visual deficits, and eventual mortality. Early diagnosis and timely HCT is a recommended treatment approach for select patients prior to the development of end-organ damage. A comorbid bleeding disorder presents a unique challenge in the setting of MIOP and cord blood HCT given the additional risk factors for bleeding including delayed engraftment, a high risk of developing sinusoidal obstruction syndrome, and potential need for emergent invasive procedures. To our knowledge, this is the first report of a patient with an autosomal recessive form of MIOP who successfully underwent a cord blood HCT complicated by the presence of mild hemophilia A and HCT-related complications including delayed engraftment, sinusoidal obstruction syndrome, and need for multiple invasive procedures (e.g., ventriculostomy, tracheostomy) without clinically significant bleeding. Given the underlying diagnosis of MIOP and need for HCT, the challenge of mitigating the significant risk of bleeding in a patient with a comorbid bleeding disorder is discussed.

Transjugular intrahepatic portosystemic shunt for the treatment of sinusoidal obstruction syndrome in a liver transplant recipient and review of the literature.

Sinusoidal obstruction syndrome (SOS) is a rare, life-threatening clinical syndrome resulting from sinusoidal congestion, and it is characterized by hepatomegaly, ascites, weight gain, and jaundice. The frequency of this condition after liver transplantation (LT) is low, but when SOS is severe and refractory to medical therapy, the ultimate solution is retransplantation. We describe a patient with SOS after LT who was successfully treated by the placement of a transjugular intrahepatic portosystemic shunt (TIPS). Although information on this approach is scarce because of the low incidence of SOS in LT patients, we review the available literature on treating this condition with a TIPS. On the basis of the reported information and our patient's outcome, we suggest that prompt TIPS placement can be considered for SOS when medical treatment fails. Nonetheless, a formal assessment and prospective studies are needed to confidently indicate TIPS placement in this situation.

Experience with duplex sonographic evaluation of meso-rex bypass in extrahepatic portal vein obstruction.

Meso-Rex bypass is a surgical procedure for managing extrahepatic portal vein obstruction in children. Although duplex sonography has been used for assessing the patency of the bypass graft and the changes in the intrahepatic portal venous system after the surgery, there was little sonographic description of functioning and dysfunctioning bypass grafts found in the literature. In this case series, we retrospectively evaluated duplex sonography of functioning and dysfunctioning bypass grafts in 5 pediatric patients who received meso-Rex bypass grafts. Sonography was performed preoperatively and postoperatively within 48 hours, 1 to 2 weeks later, and at follow-up 1 month and up to 3 years later. Changes in the direction and velocity of the flow in the intrahepatic portal veins and bypass grafts and diameters of the grafts and the left portal veins were analyzed. Preoperative sonography revealed varied extension of extrahepatic portal vein occlusion with cavernous transformation and diminished intrahepatic portal venous flow, whereas postoperative studies showed a rapid increase of the intrahepatic portal flow via the meso-Rex bypass graft in all cases. A patent graft with reversed flow in the left portal vein was a predominant feature of a functioning graft. In contrast, absent flow in the graft with diminished flow or an altered flow direction in the left portal vein indicated graft failure. It is believed that duplex sonography provides a valuable tool for monitoring the hemodynamic changes in the portal venous system and detecting graft malfunction.

Significance of isolated hepatic veno-occlusive disease/sinusoidal obstruction syndrome after liver transplantation.

After liver transplantation (LT), hepatic veno-occlusive disease (VOD), which is also known as sinusoidal obstruction syndrome (SOS), has been reported initially in relation to azathioprine use and subsequently in relation to acute rejection (AR). Isolated veno-occlusive disease (iVOD)/SOS raises some questions about its significance and especially its treatment. From the post-LT biopsy samples of 1364 patients (2000-2008), 31 patients with index biopsy samples showing VOD/SOS (2.3%) were identified. After a review of the index biopsy samples and previous biopsy samples, those patients not exposed to azathioprine therapy were subdivided into 2 groups according to the absence or presence of AR. Fifteen of the 31 patients had no previous evidence of AR, whereas 16 experienced episodes of AR (before or concurrently with VOD). The 2 groups were similar in terms of demographic and clinical data and the range of histological centrilobular changes. AR episodes were characterized by an endothelial predilection. iVOD/SOS occurred later than acute rejection-related veno-occlusive disease (AR-VOD)/SOS (mean times of 65 and 4.4 months, respectively, P = 0.0098). There was a tendency for iVOD/SOS to progress less frequently to chronic rejection in comparison with AR-VOD/SOS (3/15 versus 9/15, P = 0.06). The histological resolution of iVOD/SOS was significantly more frequent in patients who benefited from increased immunosuppression in comparison with those who did not (5/7 versus 2/8, P = 0.05). When the groups were considered together, the same result was obtained (14/18 versus 4/12, P = 0.024). In conclusion, despite a constant overall prevalence of VOD/SOS, the proportion of iVOD/SOS has increased. The histological resolution of iVOD/SOS after increase in immunosuppression suggests an immune-mediated origin. Better optimization of immunosuppression may be a curative treatment.

Consequences of chemotherapy on resection of colorectal liver metastases.

The response rate of colorectal metastases to chemotherapy, ranging from 50 to 60%, has been shown to be a prognostic factor. Complete pathologic and radiological response rates are approximately 4 and 7%, respectively. Hepatotoxic effects of oxaliplatin and irinotecan on the non-tumoral liver parenchyma have been reported and are incriminated in vascular changes (sinusoidal obstruction syndrome [SOS]) and chemotherapy-associated steatohepatitis (CASH). Oxaliplatin-based regimens are associated with an increased risk of vascular lesions and irinotecan-based regimens are associated with increased risks of steatosis and steatohepatitis. SOS increases morbidity after major liver resection, mostly after administration of more than six cycles of neoadjuvant systemic chemotherapy. CASH increases morbidity and mortality rates after hepatectomy. Preliminary results have shown that the addition of targeted molecular therapy (bevacizumab or cetuximab) to conventional chemotherapy does not increase the postoperative morbidity or mortality rates after hepatectomy and does not create additional injury to the non-tumoral liver parenchyma. However, bevacizumab may impair regeneration of the future remnant. Chemotherapy may reduce the sensitivity of CT scan and PET scan in the detection of metastases.

Sinusoidal obstruction syndrome and nodular regenerative hyperplasia are frequent oxaliplatin-associated liver lesions and partially prevented by bevacizumab in patients with hepatic colorectal metastasis.

AIMS: Because of its efficacy, oxaliplatin (OX) is increasingly used as a chemotherapeutic agent in the treatment of colorectal liver metastases (CRLM). Oxaliplatin-associated liver toxicity has been reported and can affect clinical practice, but studies on its prevalence and a full pathological description are lacking. The aims of this study were to fill this gap by providing, from a pathologist's perspective, a detailed assessment of the spectrum of hepatic lesions associated with OX, to suggest a scoring system to quantify them, and to investigate the protective effect of bevacizumab against OX-associated damage. METHODS AND RESULTS: The spectrum of oxaliplatin-associated liver lesions was investigated in a multi-institutional series of surgically resected CRLM (n = 385). Among 274 patients treated by OX, 54% had moderate/severe sinusoidal obstruction syndrome (SOS). Peliosis, centrilobular perisinusoidal/venular fibrosis and nodular regenerative hyperplasia (NRH) developed in 10.6%, 47% and 24.5%, respectively. The 111 patients treated by surgery alone had no lesions. Hepatic lesions were less severe in patients treated with OX/bevacizumab (n = 70) compared with the group treated by OX alone (n = 204), with an incidence of moderate/severe SOS (31.4% versus 62.2%), peliosis (4.3% versus 14.6%), NRH (11.4% versus 28.9%, respectively) and centrilobular/venular fibrosis (31.4% versus 52%, respectively) (P < 0.001). CONCLUSIONS: Pathologists should be aware of the distinctive lesions associated with OX and of their high prevalence. OX-related lesions are less frequent in patients treated with bevacizumab, suggesting that this drug has a preventive effect. Uniform criteria for diagnosis and grading of OX-associated lesions should help to include histological data in the optimal multidisciplinary management of CRLM.

Hepatic regeneration is decreased in a rat model of sinusoidal obstruction syndrome.

BACKGROUND AND OBJECTIVES: Oxaliplatin is a chemotherapeutic drug for colorectal adenocarcinoma able to extend the indications for resection of colorectal liver metastases. However, the drug may severely injure hepatic sinusoids, inducing a sinusoidal obstruction syndrome in non-tumoral parenchyma with a risk of decreased regeneration in the remnant liver following partial hepatectomy. METHODS: We then investigated the evolution of hepatic functions and liver regeneration following partial hepatectomy in rats with sinusoidal obstruction syndrome. The sinusoidal obstruction syndrome was induced with a single intragastric administration of monocrotaline (MCT). RESULTS: MCT administration induced obstruction of the hepatic microcirculation and increased portal pressure, hepatic VEGF expression, and Ki67 positive hepatocytes. A mild cholestasis was present without modification of hepatic tests. Following a 70% hepatectomy, liver regeneration was significantly impaired by MCT administration and this impaired regeneration was associated with hepatocellular injury evidenced 1 week after hepatectomy. CONCLUSIONS: The presence of sinusoidal obstruction syndrome impairs hepatic regeneration in this rat model of sinusoidal obstruction syndrome.