Immunoglobulin G4 (IgG4)-Related Hepatic Inflammatory Pseudotumour: The Disguised Malignancy Mimicker!

IgG4-related disease (IgG4-RD) is a complex systemic condition that can affect virtually every body organ. It has highly variable clinical presentation, indistinguishable from many inflammatory and neoplastic diseases. There are overlapping biochemical and imaging features making prospective diagnosis difficult without a high index of suspicion. One of the varied presentations of IgG4-RD is the formation of pseudotumours, which are benign masses composed of inflammatory cell infiltrates and fibrous components. It is relatively straightforward to suspect the occurrence of such pseudotumours in patients with known IgG4-RD disease or with multiorgan or systemic involvement. However, if present as an isolated initial manifestation of this disease, they may be underdiagnosed in the preoperative period, as biopsy may be complicated in every patient with a resectable tumour before surgery with imaging features consistent with a typical malignant mass for that particular organ. The present case describes the occurrence of IgG4-related inflammatory pseudotumours (IPT) in a patient who was diagnosed postoperatively due to the absence of any other manifestation of this disease elsewhere in the body.