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.