Hepatic Vascular Involvement in Adenosine Deaminase 2 Deficiency (DADA2): Case Reports and Literature Review.

Background and Clinical Significance: Deficiency of Adenosine Deaminase 2 (DADA2) is a rare monogenic vasculopathy characterised by systemic inflammatory and immunodeficiency features. Although neurological and haematological manifestations are well-documented, hepatic vascular involvement remains underappreciated. This report aims to describe the clinical and imaging characteristics of hepatic vascular involvement in a patient with DADA2 and to illustrate the evolution of hepatic lesions during long-term Etanercept therapy. In addition, we provide a synthesis of the available evidence on hepatic manifestations in DADA2, emphasising vascular pathology, clinical presentation, and therapeutic implications. Case Presentation: We describe a girl with early-onset DADA2 presenting with recurrent systemic inflammation, hypogammaglobulinaemia, vasculopathy, and two childhood strokes, followed by the development of multiple FNH-like hepatic nodules on CEUS and MRI with persistently elevated GGT. Genetic testing confirmed biallelic ADA2 mutations, and treatment with Etanercept led to sustained clinical stabilisation and marked regression of liver lesions over a nine-year follow-up period. Her older sister, carrying the same mutations, showed a milder phenotype without hepatic involvement but experienced a mesenteric vascular event. Conclusions: Large regenerative nodules with an FNH-like appearance on CEUS or MRI have not been previously reported in this setting. In our patient, Etanercept therapy produced a favourable hepatic response, reflected by a significant reduction in both the number and size of the lesions. Our case contributes to the understanding of liver disease in DADA2 and the influence of imaging and treatment on the hepatic manifestations of the condition.