Clinical Interrogation for Unveiling an Isolated Hypophysitis Mimicking Pituitary Adenoma

Hypophysitis is a rare disease entity mimicking a pituitary adenoma. Despite crucial disease involving a pituitary gland which is a main component of the hormonal axis, there have been minimal researches regarding the hypophysitis. In this study, we described the constellation of the preoperative findings including clinical, radiologic, and endocrinologic features, as well as postoperative outcomes of the hypophysitis.

The authors reviewed the data retrospectively of a total of 2814 patients who underwent microsurgery at our institution to treat a pituitary mass lesion. Among them, the patients proven as hypophysitis in histologic examination were enrolled, followed by stratification into tumor-associated hypophysitis and isolated hypophysitis depending on the existence of associated tumor lesion. As a result, a total 21 cases were enrolled consisting of the 13 cases of tumor-associated and the 8 cases of isolated hypophysitis. In this study, the isolated hypophysitis was focused on the analysis. All patients with isolated hypophysitis were evaluated the clinical, radiologic, and endocrinologic tests preoperatively. After microsurgery, all patients had a minimum follow up of 6 months (6∼72 months). The clinical symptoms, endocrinologic tests, and brain MRI were checked at every 6 months during first 2 year, since then, at every 12 months.

Among 2814 cases of pituitary mass lesion underwent microsurgery, the hypophysitis were found 21 cases (0.74 %). The 13 cases were the tumor-associated hypophysitis, consisting of rathke's cleft cyst (7 cases), craniopharyngioma (3 cases), pituitary adenoma (2 cases), and germinoma (1 case). The 8 cases were the isolated hypophysitis including lymphocytic (4 cases), granulomatous (3 cases), and IgG4-related (1 case) hypophysitis. The patients presented a wide range of clinical symptoms from general weakness to panhypopituitarism. In addition, the most remarkable radiologic features of the isolated hypophysitis were infundibular thickening and the low signal intensity in T1WI and T2WI. All 8 patients with isolated hypophysitis presented endocrinologic deficiency with various extent in a preoperative biochemistry. After surgery, the hormonal status were not changed in 4 patients (50%), however, aggravated in 4 patients (50%). The 3 patients (37.5%) complained visual field defects in preoperative ophthalmologic test, but improved all after surgery.

In this study, the preoperative clinical manifestations, radiologic and endocrinologic features of hypophysitis were described comprehensively. In addition, we also revealed the long-term outcomes of hypophysitis in the aspect of visual function and endocrinologic outcomes. Preexisting visual field defects were improved in all patients (3 cases). However, all patients presented endocrinologic deficiency in preoperative biochemistry, among them, the 4 patients (50 %) were unchanged and the 4 patients (50 %) were exacerbated after surgery. In conclusion, the visual outcomes were satisfactory, however, the endocrinologic outcomes were vice versa, because the preoperative endocrinologic deterioration was unchanged or even aggravated after surgery in some cases.