Inflammatory Pseudotumors (Inflammatory Myofibroblastic Tumors) are benign fibroinflammatory hepatic masses that can mimic malignancy radiographically and clinically. They are often associated with infection, trauma, or biliary intervention, and may be linked to IgG4-related disease.  - Definition = Localized mass of myofibroblasts, collagen, and inflammatory infiltrate without true neoplastic potential. Pathogenesis is thought to be reactive or autoimmune.  - Imaging characteristics = Appears as a solid mass with variable arterial enhancement and delayed progressive enhancement reflecting fibrous content; may show ill-defined margins and capsular retraction, mimicking malignancy. MRI typically demonstrates T1 hypointensity and heterogeneous T2 signal (often relatively hypointense compared with malignancy due to fibrosis). May show restricted diffusion and delayed enhancement, with no hepatobiliary phase uptake. Imaging may regress on follow-up with treatment of underlying inflammation.  Subtypes =  - Classic inflammatory pseudotumor – postinfectious or idiopathic.  - IgG4-related sclerosing pseudotumor – autoimmune variant, often steroid-responsive.  Treatment & Surveillance =  - Diagnosis often requires biopsy to exclude cholangiocarcinoma or metastasis.  - Management is typically conservative with observation, antibiotics, or steroids for confirmed benign disease.  - Surgical resection reserved for diagnostic uncertainty or symptomatic, enlarging lesions.  - Follow with multiphasic CT or MRI every 3-6 months until resolution. Stop imaging once lesion resolves or remains stable for >1 year.