Mimic of malignancy: delineating IgG4-related disease and lymphoma.

Here, we describe the case of a 74-year-old man who was incidentally found to have a hepatic lesion during routine screening. Additional diagnostic studies demonstrated elevated IgG4 levels, IgG4 plasma cell-predominant lymphadenopathy and an inflammatory retroperitoneal mass encasing the bilateral ureters and the aorta. Given the concurrence of a lymphomatous process and IgG4-related disease (IgG4-RD), a multidisciplinary approach was required to determine whether targeting the lymphoma or IgG4-RD would be most efficacious. Discussions led to the decision to target treatment against IgG4-RD with systemic glucocorticoids, and subsequent imaging showed resolution of all lesions. To date, the patient remains symptom-free and has not experienced recurrence of his disease. This case highlights the importance of multidisciplinary care and the challenge inherent in targeting treatment between IgG4-RD and a concomitant lymphomatous process.