Category: Pituitary Disorders/Neuroendocrinology
Granulomatous hypophysitis(GH) is a rare inflammatory disease of the pituitary gland. The incidence of this disease is 1 in 10 million per year. We report a rare case of Hypophysitis due to Giant cell arteritis (GCA).
A 54-year-old female with a history of hyperparathyroidism s/p 3 gland parathyroidectomy, primary hypothyroidism presented with symptoms of polyuria, polydipsia. She has a history of GCA diagnosed in 2016 when she presented with recurrent strokes and is currently being treated with steroids and methotrexate. She had dilute urine with urine osmolality of 73 mosm/kg in the setting of elevated serum osmolality of 300 mosm/kg consistent with a diagnosis of Diabetes Insipidus (DI). Her renal functions, calcium, and glucose were normal. MRI sella showed new finding of homogenous enlarged pituitary gland measuring 1.6cm with thickening of the infundibulum. Further testing showed normal prolactin, normal IGF-1 and elevated gonadotrophins consistent with her postmenopausal state. Adrenal axis was not tested as she was already on steroids.
For her DI, she was treated with desmopressin 0.1 mg twice daily with symptomatic improvement. We discussed high dose steroid treatment for her hypophysitis, but the patient was concerned about the side effects and hence was treated with prednisone 20mg daily tapered over two months to her maintenance dose. Repeat MRI sella 3 months later showed a decrease in the size of the pituitary gland as well as infundibular stalk thickening.
Hypophysitis is divided into 4 types with GH being one of them. Patients present with variable symptoms depending on the extent of pituitary involvement and hormonal axis affected. Our patient presented with DI 2 years after she was diagnosed with GCA and imaging findings were suggestive of hypophysitis. The pathogenesis of GH is due to infiltration with multinucleated giant cells, some forming granulomas, and variable amounts of lymphocytic infiltration and fibrosis. High-dose pulse steroids have been shown to reduce the mass effect in a small number of patients with hypophysitis, but there is no consensus on the duration and dosage of steroids. Data on use of immunosuppressive medications in GH is limited, with few case reports showing improvement with the use of Azathioprine, Rituximab in patients with progressive disease.
Granulomatous hypophysitis is a rare inflammatory condition that mimics pituitary adenoma and should be considered in the differential diagnosis of pituitary mass. High dose glucocorticoid therapy may be considered, and patients need frequent monitoring of pituitary functions as well as imaging.
Clinical instructor, Division of Diabetes Endocrine and Metabolism, University of Nebraska Medical Center