Endocrine Abstracts

IgG4 related hypophysitis is a recently described entity belonging to the IgG4 related diseases. It is characterised by markedly elevated serum IGG4 levels and tissue infiltration by IgG4 positive plasma cells. To date, 34 cases of IgG4 related hypophysitis have been described but only a handful were in women or biopsy proven. We describe a case of a 58 year old woman who presented with transient headache. She also complained of polyuria and nocturia. She had a thyroidectomy for treatment of hyperthyroidism 10 years previously. MRI pituitary revealed a pituitary mass with marked diffuse stalk thickening. Dynamic evaluation of her anterior pituitary function revealed raised prolactin and severe GH deficiency. An 8-h water deprivation test showed partial diabetes insipidus. Ferritin, serum ACE, β-HCG, alphafetoprotein, autoimmune screen and ANCA were negative. Chest and abdominal imaging and breast mammography showed no malignancy. A transsphenoidal pituitary biopsy showed evidence of hypophysitis with fibrosis and increased number of histologically benign plasma cells and >10 positive cells per HPF on IgG4 immunocytochemistry, which is highly characteristic of IGG-4 related hypophysitis. Her plasma IgG4 level was normal. She was determined to have IgG4 related hypophysitis as per the criteria proposed by Leporati et al. in 2011. She was commenced on glucocorticoids and is due for a follow up MRI in 6 months. IgG4 related hypophysitis is a rare disorder, which was first described in 2004 based on clinical data. Of the 34 cases recorded in the literature, 29 were men and five were women. The majority of documented cases have been from Japan. While initial case reports were of more severe disease, more recently there have been case reports of patients with milder variants, with one patient reported with normal pituitary function. Accurate diagnosis is essential, as previous reported cases have shown improvement with glucocorticoid therapy. This case illustrates that when an enlarged pituitary gland/stalk is detected, IgG4 hypophysitis should be considered in the differential diagnosis regardless of pituitary function and serum IgG4 level.