Pulmonary IgG4-related disease and colon adenocarcinoma: possible paraneoplastic syndrome.

Malignancy has a complicated association with immunoglobulin G4-related disease (IgG4-RD) both being an item in the differential diagnosis as well as malignancy occurring in the background of IgG4-RD in the same organ. However, recently there is evidence of higher rates of distant malignancy in patients with IgG4-RD. Here we report a case of pulmonary IgG4-RD potentially consistent with a paraneoplastic phenomenon which improved with treatment of the underlying colon adenocarcinoma.