Immunoglobulin G4-Related Disease (IgG4-RD) with Associated Sarcoidosis

Immunoglobulin G-4 related disease represents a collection of tumefactive entities associated with an abundance of infiltrating IgG4 positive plasma cells, which was described first in patients with chronic pancreatitis. Since then, IgG4 related disease has been described in multiple organ systems including the orbit. We describe here a patient with a history of sarcoidosis who was subsequently found to have IgG4 related disease of the orbits, diagnosed by histology and immunohistochemical staining for IgG and IgG4. Microscopic examination of the orbital biopsy demonstrated storiform fibrosis and obliterative phlebitis, as well as a specific IgG4 ratio > 40%. Six years prior, the patient was diagnosed with sarcoidosis clinically and histologically, which proposes the question of a relationship between the two entities. It is unclear from the literature whether IgG 4 related disease represents a diagnosis of its own, and therefore an incidental finding in our case; or whether it is associated with or a consequence of chronic inflammatory diseases in general or in specific cases such as long standing sarcoidosis. Chronic inflammatory processes are known to terminate in proliferative fibrosis at times, rich with IgG4 predominant plasma cells that are histologically identical to findings seen in IgG4 related disease.