When One Autoimmune Condition Predisposes You to Another!

Introduction: Lymphocytic hypophysitis (LYH) is an autoimmune condition in which pituitary gland is infiltrated by lymphocytes, plasma cells and macrophages. It is more common in pregnant and postpartum women, presenting with headache, visual field changes and one or more pituitary hormone impairment. Case Presentation: 32year-old female recently diagnosed with RA complicated by uveitis, presented to our facility with headache, shortness of breath, blurred vision and dysphagia. MRI head revealed a 1.9cm sellar mass with suprasellar extension displacing the optic chiasm. There was clear thickening of the pituitary stalk which raised suspicion for autoimmune hypophysitis. Exam in the ED revealed an anxious female wit hypertension, tachycardia and BMI 30. The rest of the physical exam was unremarkable. Her pituitary gonadal axis workup revealed panhypopituitarism with TSH 0.01uIU/ml, FSH <0.3Miu/ml, LH <0.3mIU/ml, ACTH <5pg/ml, IGF-1 31ng/ml and prolactin 14.4ng/ml. She was started on prednisone 50mg daily and on levothyroxine 150mcg daily. On day 2, she developed polyuria and the work up revealed a serum sodium of 146 meq/L, serum osmolality 315mOsm/kg, urine osmolality 281mOsm/kg and urine output 5.6L in 24hrs. The diagnosis of DI was made and she was started on desmopressin. On day 7, the serum sodium normalized and she did not require any other dose of desmopressin. On the day of discharge, a repeat MRI head was done which showed reduced enhancement of the pituitary which was reassuring. Discussion: LYH is a neuroendocrine disorder characterized by autoimmune inflammation of the pituitary gland with various degrees of pituitary dysfunction. Associated autoimmune diseases are seen in 18%– 50% of cases of AH. The most commonly-associated disease is autoimmune thyroid disease (15%–25%), while concurrent autoimmune conditions including RA are reported as well. Homogenous symmetrical enlargement of the pituitary gland, a thickened non deviated stalk, and a prompt, intense and homogenous enhancement of the mass after gadolinium contrast are the characteristic findings on MRI. Spontaneous resolution is the usual course and surgery is indicated only when the symptoms of sellar compression are serious and progressive. Conclusion: LYH is predominantly a disease of young females. We present this case in order to create awareness about the co-existence of LH with other autoimmune conditions and its usual course of regression with steroids.