The Histopathologic Features of Sickle Cell Hepatopathy: A Multi-Institutional Study

From early development to maturity: a phenotypic analysis of the Townes sickle cell disease mice

Well-characterised mouse models of disease may provide valuable insights into pathophysiology. This study characterises the Townes mouse model of sickle cell disease (SCD) and establishes a time window in which the disease is present but does not progress significantly in terms of severity. We examined Townes mice with the HbAA, HbAS, and HbSS genotypes from young (4 weeks) to mature (5 months) stages of life to assess the disease state at different ages and any progression. We conducted blood tests, histological organ damage evaluations, and metabolic assessments to identify a suitable time frame for study based on welfare considerations. Townes HbSS mice displayed key SCD features such as anaemia, haemolysis, thromboinflammation and organ pathology. Notably, these manifestations remained relatively stable over the study period, indicating a stable phase suitable for conducting intervention studies. Mice with HbAS and HbAA genotypes served as comparative controls, showing minimal to no pathology throughout. These findings are valuable for future research on SCD and may ultimately lead to the development of more effective treatments for this debilitating disease.

Portosinusoidal Vascular Disorder: A Heretofore Unrecognized Manifestation of Sickle Cell Disease?

Portosinusoidal vascular disorder (PSVD) is a recently proposed histopathologic entity that encompasses a spectrum of often subtle hepatic microvascular lesions and related microarchitectural abnormalities. Clinical manifestations may arise years after histologic diagnosis and include extrahepatic portal vein thrombosis and portal hypertension. While the histopathologic features of PSVD have been associated with numerous clinical conditions, most notably prothrombotic/vasculopathic disorders, PSVD has not yet been described in sickle cell disease. This gap is striking given the central role of microvascular dysfunction in sickle cell disease and well-described patterns of hepatic injury and dysfunction in this population. This case series is the first to explore the prevalence and pathogenesis of PSVD in sickle cell disease. Forty-one diagnostically adequate liver biopsies from patients with sickle cell disease were identified across the archives of 5 tertiary medical centers. All biopsies exhibited at least 1 histopathologic feature associated with PSVD (mean 3.8 features/case). Overall, 90.2% of patients met the criteria for a diagnosis of PSVD based on the presence of specific histopathologic and/or clinical findings. Immunohistochemical stains for von Willebrand factor, CD34, and glutamine synthetase were performed on 36 cases (87.8%). Aberrant (centrilobular sinusoidal) CD34 and von Willebrand factor staining was present in 97.2% and 86.1% of cases, respectively. Glutamine synthetase reactivity was at least mildly decreased in zone 3 hepatocytes in 52.8% of cases. We posit that chronic erythrocyte sickling results in dysfunction and remodeling of the portal microvasculature, culminating in regression of zone 3 hepatocytes. The presence of PSVD may explain, at least in part, the hepatic dysfunction observed in this patient population. These patients may also benefit from extended clinical surveillance for portal hypertension and other complications. While subtle and prone to overdiagnosis, the features of PSVD should be carefully considered when interpreting liver biopsies from patients with sickle cell disease.