Significance of high serum IgG4 in complete or non-full-fledged IgG4-related disease-a retrospective investigation of 845 patients and its clinical relevance.

Smoking may precipitate IgG4-RD. IgG4-RD with pancreato-hepatobiliary disease is closely related to allergy and neoplasm, and those with Mikulicz syndrome may result from atopy. Elderly IgG4-RD patients tend to develop CNS pathology parallel to advancing of age. The disease may probably be originated from an unknown mechanism that may sporadically evolve into malignancies.