Insights from a multicenter study on the outcomes of liver abscess after allogeneic hematopoietic stem cell transplantation

Abstract Introduction: Liver abscess (LA), a severe and potentially life-threatening infection, is characterized by the formation of purulent material within the liver parenchyma, often resulting from bacterial, fungal, or parasitic infections. In the context of hematopoietic stem cell transplantation (HSCT), liver abscess is rare but carries a high risk of mortality due to the immunocompromised state of transplant recipients. However, most existing studies on liver abscess after HSCT are case reports, and there is little information available on the risk factors and outcomes of patients with post-HSCT LA. This study aimed to systematically analyze the clinical manifestations, risk factors and outcomes of post-HSCT LA. Methods: This multicenter study reviewed data from patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) at 12 transplant centers between July 2010 and March 2025. A total of 44 patients with LA and 132 patients without LA following allo-HSCT were included in the study. Individual matching for each case was conducted by randomly selecting three individuals from the same cohort as controls according to the HSCT time (±3 months) and follow-up time (±6 months). The time intervals in this study were counted from the last day of stem cell infusion. Pearson's chi-square test, Fisher's exact test, and the Mann–Whitney U test were selected for intergroup comparisons, as appropriate. Overall survival (OS) and non-relapse mortality (NRM) were calculated and compared by the Kaplan–Meier method and log-rank test in the case and control cohorts. Univariate and multivariate Cox analyses were performed to identify risk factors associated with post-HSCT LA occurrence. Results: A total of 44 patients with post-HSCT LA were ultimately included in the case cohort, demonstrating a cumulative incidence of 0.075%. The two cohorts presented similar characteristics in terms of demographic features, post-HSCT infection, and follow-up time. Among the 44 patients in the case cohort, LA was diagnosed at a median of 61 days (IQR, 20–253). The most common symptoms were fever and abdominal discomfort, which were diagnosed in 37 (84.1%) and 26 (59.1%) of the patients, respectively. Among the 24 patients in whom pathogens were detected, the most common pathogen was Klebsiella pneumoniae (33.3%), followed by Pseudomonas aeruginosa (16.7%). The abscesses were observed by ultrasound and presented a maximum diameter of 25.0 (IQR, 15.0–34.0) millimeters. Most of the abscesses were multiple (29, 65.9%), and nearly half of the abscesses occurred only in the right lobe of the liver (20, 45.5%). Forty-two patients (89.3%) received antibiotic treatment. Thirty-eight patients (80.8%) received antifungal therapy. Seven patients (15.9%) underwent percutaneous catheter drainage because of the inefficiency of anti-infective therapy. Only 1 patient (2.3%) underwent laparoscopic drainage. This study revealed an OS rate of 68.2% and a NRM rate of 25.0% in the case cohort. By the end of the follow-up period, 14 patients (31.8%) in the case cohort had died at a median of 226 days (IQR, 93–381) after HSCT and at a median of 44 days (IQR, 15–113) after the diagnosis of LA. Three patients (6.8%) died of relapse of the underlying disease, 1 patient (2.3%) died of sudden cardiac arrest, and 1 patient (2.3%) died of intracranial hemorrhage. Only 1 patient (2.3%) died directly of LA. The remaining 8 patients (18.2%) died of severe lung infection and multiple organ dysfunction. In the control cohort, 14 patients (10.6%) died at a median of 155 days (IQR, 93–185). The log-rank test revealed a significant negative influence of post-HSCT LA on OS (P = .002) and NRM (P = .010) between the case and control cohorts. In the multivariate analysis, the white blood cell (WBC) engraftment time (P = .013), grade II to IV acute graft-versus-host disease (aGVHD) (P = .000), and CD34+ cell count at transfusion (P = .005) were identified as independent risk factors for the onset of post-HSCT LA. Conclusions: Post-HSCT LA had a significant negative influence on OS and NRM in allo-HSCT recipients. WBC engraftment time, grade II to IV aGVHD, and the CD34+ cell count were identified as independent risk factors for the occurrence of LA. To our knowledge, this is the first cohort study that thoroughly underlines the clinical features, outcomes and risk factors for post-HSCT LA.