Endocrine Abstracts

IgG4-related hypophysitis, a type of IgG4-related disease, is a rare condition. It appears to be sensitive to glucocorticoids in most patients, but its recurrence is likely.

Clinical case: A 17 year-old girl was referred for hypotonic polyuria and polydipsia of 1 month duration. Water deprivation test was suggestive of central diabetes insipidus. Basal and dynamic assessment of pituitary anterior function were unremarkable. Patient did suffer from autoimmune thyroiditis and autoimmune gastritis. Serum IgG4 were found high [269 mg/dl (49-66)] as well as serum IgE [2600 U/ml (50-120)]. Magnetic resonance imaging (MRI) of the sella turcica showed a clear enlargement of the pituitary stalk with an intense and homogeneous contrast enhancement, the neurohypophysis bright spot, on pre-contrast images, could not be identified. IgG4-related neuroinfundibulo-hypophysitis was suspected on clinical grounds. Imaging studies, such as total body positron emitted tomography and abdomen ultrasound, excluded other localization of disease.B-cell depletion therapy with Rituximab was administered (1 g iv for two doses in 14 days), preceeded by metilprednisolone pulse therapy. Oral therapy with metilprednisolone, started at 40 mg/d, was continued for 6 months. To control polyuria, desmopressin was started at 180 mcg/d.Three months after first treatment, control MRI showed a normal sized pituitary stalk with normal enhancement after gadolinum, serum IgG4 and IgE were reduced (60% and 30%, respectively) although still above normal range. After 6 months, at the end of metilprednisolone therapy, sellar MRI still showed a normal pituitary and stalk. IgG4 and IgE were decreased, pituitary anterior function was normal. Diabetes insipidus was still present, however the dose of desmopressin needed to control polyuria was lower than at diagnosis (60 mcg/d).

Conclusion: IgG4 related hypophysitis is a rare condition that may benefit from B-cell depletion therapy. Goal of treatment is remission of pituitary inflammation and ultimately of diabetes insipidus. Careful follow-up is needed in order to spot recurrence of the disease, in the pituitary or in other sites.