A 63-year-old female patient was referred to our hospital in February 1994 for a
pituitary tumor. On a previous examination, in 1973, she had a
goiter, nonspecific symptoms and only an elevated serum T3. In 1984 she had become hypothyroid, her
goiter had increased, serum T4 was 69 nmol/L, TSH 34.4 mU/L, and TPO
antibodies were positive.
Hypothyroidism due to
autoimmune thyroiditis was diagnosed and she received L-T4 100 micrograms/day. In 1985 and 1986, serum TSH had decreased but remained slightly elevated, while T4 was at the upper limits of normal. From 1987 to 1989 her serum TSH rose from 9 to 20 mU/L and remained at that level for the ensuing 4 years in spite of increasing L-T4 up to 150 micrograms/day. In October 1993, after discontinuing L-T4 for 6 weeks, TSH was 23.7 mU/L, T4 170 nmol/L, 131I thyroid uptake 52%, and the CT scan showed a large
pituitary tumor with suprasellar extension. On preoperative investigation TSH was 40-51 mU/L with no response to TRH or
GnRH. The alpha-subunit was increased at 6.33 micrograms/L with the alpha-TSH/TSH molar ratio of 1.23.
Prolactin was elevated, but plasma
cortisol, FSH, and LH were low. At surgery, we found a large
chromophobe adenoma with few PAS-positive granules and with immunostaining positive for TSH and
prolactin. From the clinical and
biological data, we can conclude that the patient had probably a TSH-secreting
adenoma since the
goiter was first detected. The development, however, of
autoimmune thyroiditis with
hypothyroidism considerably modified the presentation of the disease and may have accelerated the growth of the
tumor.