Idiopathic Hypophysitis

Abstract

Introduction: Hypophysitis is a heterogeneous condition that leads to inflammation of the sella / suprasellar region, potentially resulting in hormonal deficiencies or mass effects. Prevalence of hypophysitis ranges from 0.2% to 0.88%. Annual incidence of hypophysitis is 1 case per 9 million individuals. We present an interesting case of idiopathic hypophysitis. Clinical Case: A 52-year-old female was evaluated for secondary hypothyroidism. Patient complained of excess fatigue, weight gain, headaches, polyuria with nocturia and vision changes. She was seen by ophthalmology for formal visual field testing revealing right superior quadrantanopia. Labs significant for TSH 4 uIU/mL (ref range 0.27-4.2uIU/mL), FT4 0.72ng/dL (ref range 0.93-1.7 ng/dL), Anti TPO ab negative, AM cortisol 8.9UG/dL, ACTH 18pg/mL, IGF1 127ng/mL, prolactin 7ng/mL, FSH 102MIU/mL, LH 41 MIU/mL. MRI sella revealed homogenous enhancement of the pituitary with convex superior margin - 0.8*1*0.9cm concerning for hyperplasia. Due to the concern for hypophysitis, an extensive inflammatory workup was pursued which was negative. She was started on thyroid hormone replacement and DDAVP. An empiric trial of high dose steroids failed to provide any relief. During workup, patient complained of transient right sided face and arm tingling, diagnosed with TIA and started on aspirin. Due to worsening headaches, a pituitary biopsy was pursued. Pathology significant for glandular tissue ruling out inflammatory, neoplastic, and infectious etiologies. Neurology diagnosed the patient with hemicrania continua. Patient is currently maintained on thyroid hormone replacement and DDAVP with close follow-up. Discussion: The incidence of hypophysitis has recently increased due to increased awareness and also due to the use of medications like ICI. Primary hypophysitis is mostly due to autoimmune etiology. Secondary hypophysitis could result from infections, neoplastic conditions or an adverse effect of medications. Clinical presentations ranges from being asymptomatic to having features of hypopituitarism. Usually presents with mass effect, visual symptoms due to the upward expansion of the pituitary gland impinging the dura mater and optic chiasm. This is followed by symptoms of hormone deficiency, central DI and hyperprolactinemia. Central AI has been reported in 20%-75%, central hypogonadism in 15%-60%, central hypothyroidism in 25%-58%, GH deficiency in 5%-41%, and prolactin deficiency in 13%-25%. Typical MRI findings include, homogeneous pituitary contrast enhancement, pituitary stalk thickening and loss of posterior pituitary bright spot, ‘figure of 8’ appearance, ‘dural tail’. Treatment consists of surgery, anti-inflammatory medications, and radiotherapy. Glucocorticoid treatment is the cornerstone for medical management; however, the overall recurrence rate is high.