Clinicopathologic features and outcomes of hepatic inflammatory pseudotumour (IPT) and hepatic IPT-like lesions

Hepatic inflammatory pseudotumours (IPTs) are nonneoplastic hepatic masses characterized by variably fibroblastic stroma and inflammatory infiltrate, hypothesized to arise as part of a response to infection or prior surgery. The aim of this study was to evaluate the clinicopathologic features and outcomes of biopsy-proven hepatic IPT as well as other cases with IPT-like histologic features. A database search at our institution identified cases with a pathologic diagnosis of hepatic IPT (n = 80) between 2000 and 2023. Histologic features (stromal quality, inflammatory cell components, granulomas, and necrosis) were evaluated. Past medical and surgical history, microbiologic studies, and outcomes were reviewed retrospectively. Patients frequently had a past medical history of malignancy (34%), biliary disease (15%), or prior intraabdominal surgery (24%), and often presented with multifocal hepatic lesions (36%). Variable inflammatory backgrounds were present, including histiocytic (36%), lymphoplasmacytic (34%), or neutrophilic (24%). Specific organisms were identified in 15% of cases, most commonly Klebsiella and Staphylococcus species. Most patients with available clinical follow-up demonstrated radiologic resolution and/or had repeat negative biopsy; a minority of patients (8%) were subsequently diagnosed with neoplastic hepatic lesions. No significant association was seen between histologic features and the subsequent clinical or pathologic diagnosis of hepatic neoplastic lesions. Hepatic IPT is a heterogeneous entity that can present in a variety of clinical scenarios and show a wide morphologic spectrum. These lesions often regress spontaneously or with antibiotics. A subset of cases with hepatic IPT-like histologic features were subsequently diagnosed with malignancy, emphasizing the need for continued follow-up and repeat biopsy depending on clinical and radiologic features.