PMON157 Evidence For Locally Produced Cortisol in Pituitary Tissue

Double or multiple pituitary adenomas are rare and account for only 1.6-3.3% of all corticotroph tumors. We describe 2 distinct pituitary corticotroph adenomas in a 43-year-old female presenting with ACTH-dependent Cushing disease (CD). Although pre-operative pituitary MRI noted a single 8×6mm left sided pituitary microadenoma, which was confirmed at trans-nasal trans-sphenoidal surgery, she was found to an additional 7mm right sided microadenoma. Histopathology confirmed 2 separate corticotroph adenomas and she exhibited immediate remission of her CD with nadir cortisol of 1mcg/dL. Whole exome sequencing demonstrated a somatic mutation in the 21-alpha-hydroxylase (CYP21A2) gene in both tumors. CYP21A2 transcript and protein expression were absent in the index case but both CYP21A2 transcript and protein were demonstrated in a series of 9 other pituitary corticotroph adenomas and 12 normal pituitary tissues. This unusual case which prompted us to examine CYP21A2 expression in the pituitary allows us to describe for the first time evidence of locally generated pituitary-derived cortisol and indicate this could play a paracrine role on the corticotroph and may contribute to growth of ACTH pituitary adenomas in some instances. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.