hypophysitis is an inflammatory condition of the pituitary gland that is often mistaken for other pituitary mass lesions . granulomatous hypophysitis is a rare inflammatory disorder , accounting for < 1% of cases involving panhypopituitarism or visual field defects with headaches . granulomatous hypophysitis commonly presents with enlargement of the pituitary gland that mimics an adenoma , making it difficult to confirm the disease until the time of surgery . in korea , only one case has been previously reported . we herein report a 31-year - old woman who had normal brain magnetic resonance imaging ( mri ) findings 4 months prior to admission and was diagnosed with granulomatous hypophysitis at the time of surgery . a 31-year - old woman was admitted to our hospital with severe headache , nausea , and vomiting . four months before admission to our hospital , she had visited the department of neurology due to a bilateral temporal headache . neurologic examination and 1 ) , so she was treated pharmacologically with a nonsteroidal anti - inflammatory drug . due to nausea and vomiting for 2 weeks , she was brought to the emergency room . her blood pressure was 110/70 mmhg , pulse rate was 58 beat / min , respiratory rate was 16 breath / min , and body temperature was 36.6. a neurologic examination revealed bitemporal hemianopsia . initial complete blood analysis revealed a white blood cell count of 4,860/mm , a hemoglobin level of 12.4 g / dl , and a platelet count of 241,000/mm . the biochemical test results were as follows : protein , 7.2 g / dl ; albumin , 4.2 g / dl ; aspartate aminotransferase , 16 iu / l ; alanine aminotransferase , 6 iu / l ; blood urea nitrogen , 5.9 mg / dl ; and creatinine , 0.5 mg / dl . the electrolyte test results were as follows : sodium , 113 meq / l ; potassium , 4.3 meq / l ; and chloride , 82 meq / l . the thyroid function test results were as follows : serum thyroid - stimulating hormone ( tsh ) level , 0.56 iu / ml ( reference range , 0.27 to 4.2 ) ; free t4 , 0.91 ng / dl ( 0.93 to 1.7 ) ; and t3 , 0.89 ng / ml ( 0.8 to 2.0 ) . we performed a combined pituitary stimulation function test and rapid adrenocorticotropic hormone ( acth ) stimulation test for further assessment . we injected regular insulin ( 0.1 /kg ) , thyrotropin - releasing hormone ( 200 g ) , and luteinizing hormone ( lh)-releasing hormone ( 100 g ) ; 2 hours later , the patient 's blood glucose level fell to 60 mg / dl and she complained of hypoglycemic symptoms . the combined pituitary function stimulation test showed no increase in serum growth hormone , acth , or tsh level . serum levels of lh and follicle - stimulating hormone were normal over time , and mild hyperprolactinemia was present with normal increments over time ( table 2 ) . t1- and t2-weighted mri showed an 18  10-mm round mass with isosignal intensity in the sella . 2 ) . prednisolone and levothyroxine were prescribed and the mass was removed using a transsphenoidal approach . the acid - fast bacilli stain , tuberculosis polymerase chain reaction , angiotensinogen - converting enzyme , and venereal disease tests yielded no abnormal finding . the patient was finally diagnosed with idiopathic granulomatous hypophysitis , and estradiol and progesterone were added to the prednisolone and levothyroxine for maintenance therapy . inflammatory pituitary lesions are extremely rare and can be classified into three clinicopathologic entities : lymphocytic , xanthomatous , and granulomatous hypophysitis . granulomatous hypophysitis , a rare chronic inflammation of the pituitary gland that creates granulomas , has been reported in < 1% of sellar lesions based on surgical findings with the transsphenoidal approach . lymphocytic hypophysitis is distinguished from granulomatous hypophysitis by the absence of nodular aggregations of epithelioid histiocytes and multinucleated giant cells , but these two diseases show ultrastructural similarities . the two entities may have the same pathogenetic background or even represent different stages of the same disease , and some authors have suggested that they represent an autoimmune spectrum from a purely lymphocytic form , constituting the predominant early lesion , to a granulomatous form appearing later . granulomatous hypophysitis , however , differs from lymphocytic hypophysitis in certain epidemiological features , which are mostly associated with pregnancy and autoimmune diseases . imaging studies can help to distinguish granulomatous hypophysitis from pituitary adenoma . in patients with granulomatous hypophysitis , mri usually shows symmetric enlargement of the pituitary gland , pre - contrast homogeneity of the pituitary mass , an intact sellar floor , and rapid enhancement of the pituitary stalk after gadolinium administration . however , these findings are not specific and are quite indistinguishable from other neoplastic or inflammatory hypophyseal processes on imaging . patients may also present with progressive chiasmal compression , hypopituitarism , amenorrhea - galactorrhea , hyperprolactinemia , fatigue , diabetes insipidus , a sudden onset of aseptic meningitis , and/or blurred vision . granulomatous hypophysitis is difficult to differentiate from a simple adenoma on the basis of clinical manifestations or imaging findings . secondary causes of granulomatous hypophysitis include infections ( tuberculosis , syphilis , and fungal ) , systemic inflammation ( sarcoidosis , wegener 's granulomatosis , crohn 's disease , and histiocytosis x ) , and foreign body reactions ( ruptured rathke 's cysts ) . hypopituitarism resolves after surgery in some cases , but many patients remain on full hormone replacement therapy , as in our case . lymphocytic hypophysitis was first presumed in the present case because of the rapidly growing sellar lesion observed on mri and the patient 's history of delivery 6 months prior to admission . however , the postoperative biopsy revealed granulomatous hypophysitis , and other examinations ruled out secondary causes of hypophysitis . in summary , idiopathic granulomatous hypophysitis is a very rare pituitary condition that is difficult to diagnose preoperatively . the treatment of this disease is surgery , which helps in diagnosis and treatment , and hormone replacement .