A case of giant retroperitoneal lymphangioma and IgG4-positive fibrosis: Causality or coincidence?

Several chronic inflammatory diseases have been found to be a subtype of IgG4-related disease, all of which have a typical clinical and histological change, which is based in particular on an overexpression of IgG4 and subsequent fibrosis. At least a part of the retroperitoneal fibrosis, which was originally classified as idiopathic, seems to be assigned to IgG4-related disease. Lymphangiomas are benign, cystic tumors that rarely occur in adults. However, there is no firm association with IgG4-related disease described in the literature to date. This report is about a patient suffering from acute renal failure due to a giant retroperitoneal cyst. Surgical resection remains incomplete in the iliac vessel area due to severe fibrosis and histology revealed features of both lymphangioma and IgG4 fibrosis. The case description is followed by a brief overview of IgG4-related disease and a consideration of whether lymphangiomas might be assigned to this topic.