ESTROGEN-RECEPTOR EXPRESSION IN HUMAN PITUITARY - CORRELATION WITH IMMUNOHISTOCHEMISTRY IN NORMAL TISSUE, AND IMMUNOHISTOCHEMISTRY AND MORPHOLOGY IN MACROADENOMAS

Forty-one human pituitary adenoma specimens were examined for the pres ence of estrogen receptor (ER) messenger ribonucleic acid and protein using a combination of ribonuclease protection assay, [H-3] estradiol ([H-3]E(2)) binding, and ER immunohistochemistry. ER messenger ribonuc leic acid prevalence was high in PRL-immunoreactive tumors (2 of 2), m oderate in GH/PRL tumors (2 of 5), and low or absent (0 of 4) in GH tu mors. In the GH/PRL-immunostaining tumors, the presence of the ER was uniformly associated with elevated serum PRL levels. Among the gonadot ropin-immunostaining tumors, 10 of 17 were ER positive; within this gr oup, those with gonadotroph adenoma characteristics were ER positive, whereas those with null cell/oncocytic characteristics were ER negativ e. Of the tumors that did not immunostain for any known anterior pitui tary hormones, 3 of 11 were ER positive. ER immunohistochemistry in 14 tumors revealed a 100% correlation with ribonuclease protection assay results, whereas [H-3]E(2) binding, determined in 9 tumors, showed an 87% correlation. In summary, it appears that PRL and a specific class of gonadotropin-immunostaining tumors (identifiable by specific chara cteristics on electron microscope) contain ER, whereas GH-immunostaini ng tumors are ER negative. ER expression in normal pituitary parallele d that in macroadenomas (GH, 2.3%; PRL, 50%; FSH, 70%; LH, 83%; TSH, 4 %; ACTH, 1%). The ER-positive tumors represent a subset whose growth a nd secretory profiles may be influenced by the gonadal steroidal milie u or by pharmacological agents that affect E(2) levels or ER function.