First reported case of IgG4-related hypophysitis without pituitary insufficiency

The authors report the first case of IgG4-related hypophysitis without pituitary insufficiency. The patient was a 55-year-old Japanese man with an enlarged pituitary gland and bitemporal hemianopsia.

Endocrine studies revealed normal pituitary function, although his serum IgG4 level was high. He underwent a transsphenoidal biopsy of the pituitary gland, and the pathological tissues were consistent with IgG4-related hypophysitis. 

Oral prednisolone was started and later tapered on the basis of changes in clinical manifestations, biochemical blood tests (including IgG4 level) and repeated imaging findings. After six months, his serum IgG4 level decreased, pituitary gland enlargement significantly ameliorated and visual field improved, with no signs of recurrence.

The patient fulfilled the suggested diagnostic criteria for IgG4-related hypophysitis but did not show hypopituitarism, although all previously reported cases of hypophysitis have been associated with pituitary insufficiency. The authors say that although they are uncertain as to why they observed normal pituitary function in their patient, a likely explanation is that since the patient underwent an annual brain scan due to suspected microvascular infarction, the pituitary lesion was detected before the onset of hypopituitarism.

They say this case suggests that when clinicians detect an enlarged pituitary, even if the patient has normal pituitary function, serum IgG4 measurement for early diagnosis of IgG4-related hypophysitis should be performed.