Immunoglobulin G4 (IgG4)-Related Hypophysitis.

We report two different cases of IgG4-related hypophysitis. In the first case, a pituitary lesion was accompanied by lymphocytic meningitis possibly mimicking tuberculous meningitis. The second case was unassociated with involvement of other organs. No histologic differences were noted between the two cases indicating that the morphologic features of the hypophysial lesion do not depend on the presence of other lesions. The pathogenesis of IgG4 hypophysitis is not known, and further study is necessary to explore the cause, progression, and influencing factors of this disease.