Endocrine Abstracts

Background

Lymphocytic hypophysitis is an unusual inflammation of the pituitary gland affecting mostly women. Its pathogenesis is still poorly understood and the presentation and clinical course vary largely. Serum prolactin levels may be low, normal, or elevated. Unlike what is observed in clinically nonfunctioning pituitary adenomas, there is not a clear hierarchy of anterior pituitary hormone deficiencies. Hypophysitismay resolve spontaneously, may relapse, and in some cases may be refractory to treatment.

Case presentation

A 47-year-old woman with history of sudden secondary amenorrhea at the age of 46 andsubsequent hot flashes, discovered galactorrhea incidentally after 6 months. Her initial evaluation revealed mild hyperprolactinemia 1532 uIU/ml (127–637), significantly low FT4 5.7 pmol/l (12–22), T4, FT3 and T3 0.8 nmol/l (1.3–3.1), mildly increased TSH 5.61 uIU/mLand increased TPOAb. Levothyroxine (LT4) 50 µg was introduced, but T4 and T3 remained low despite normal TSH, indicating central hypothyroidism, interestingly without any clinical signs. Gonadotrophic insufficiency was documented: FSH 5.4 uUI/l, LH 0.92 IU/L, E2 < 5 pg/ml. MR imaging revealed aninhomogeneous, hypodense, contrast enhancing 1.1 cm sellar mass in contact with the optic chiasm, and left deviation of pituitary stalk. Cabergoline (CAB) 0.5 mg/week was added, with rapid PRL decrease to subnormal values, but amenorrhea persisted. At presentation in our clinic, the patient had only amenorrhea with nogalactorrhea, headaches, visual impairment orpolyuria. On LT4 35 µg/day and CAB 0.25 mg/week, TSH: 4 uIU/ml, FT4 10.5 pmol/l (9–19), T3: 72.8 ng/dl (80–200), morning cortisol 12.33 µg/dl (6–22), low PRL, IGF1 83.15 ng/ml (60–240), low FSH, LH and estradiol (2.74 IU/l, 0.92 IU/l, 20.52 g/ml, respectively). A rapid GnRH test showed partialresponse of LH (4.66 IU/l), with an estradiol increase to 110.7 pg/ml. Repeated imaging (at 3 months) showed a significant shrinkage of the more inhomogenousand hypodense pituitary mass. This rapidly decreasing infiltrative-like pituitary mass associated with partial pituitary failure, possibly due to pituitary stalk compression (gonadotrophic&thyrotrophic insufficiency and mild hyperprolactinemia) suggests a possible lymphocytic hypophysitis. Confirmation could be obtained only by pituitary biopsy or surgery, which were not recommended yet.

Conclusions

Lymphocytic hypophysitis is a rare inflammatory disease of the pituitary gland which is frequently a diagnosis of exclusion. It can be associated with atypical pituitary insufficiency and with spontaneous remission of the pituitary mass. Of note, central hypothyroidism may present with low FT4/T4 and low, normal or even mildly elevated TSH.