Endocrine Abstracts

Introduction: Immune checkpoint inhibitors (ICIs), are widely used as therapeutic option in oncological patients. However, ICIs treatment is often complicated by endocrinological adverse events, such as hypophysitis. Although diagnostical approach of hypophysitis is standardized, imaging features have not been characterized yet.

Methods: Pituitary gland magnetic resonance imaging (MRI) findings were retrospectively recorded in 59 oncological patients with ICI-induced hypophysitis. Patients with cerebral or pituitary metastases were excluded. 59% of patients were treated with PD-1/PDL-1, 8% with CTLA-4, and 33% with combined PDL-1/PD-1 and CTLA-4 therapy.

Results: First MRI assessment was performed at a median time of 12 months from ICI initiation. Pituitary MRI abnormalities were described in 29 (49%) patients. Abnormal MRI findings included microadenoma (n=8/59, 14%), increased dimensions with heterogeneous enhancement of the pituitary gland (n=7/59, 12%), partially empty sellar (n=8/59, 14%), cyst at the adeno-neuropituitary border (n=2/59, 3%), reduced size of the pituitary gland (n=1/29, 2%), slight deviation of the pituitary peduncle with submergence in the sellar (n=1/59, 2%), thickening of the lower peduncle of the pituitary gland (n=1/59, 2%) and pathological tissue in sellar (possibly inflammation) (n=1/59,2%). Seven patients had a second MRI performed at a 17 months median time from the first MRI. Four patients presented with stable MRI findings. From the remaining patients, one with a microadenoma showed a partially empty sellar turcica, another one with a normal initial MRI also had a partially empty sellar turcica, and the last one with thickening of the pedicle, showed increased dimensions of the gland. Twenty patients out of 29 with an abnormal MRI presented an affected corticotrophin axis. 69% (n=6/19) of them represented mostly pituitary microadenomas. Five patients out of 29 presented with corticotropin and thyrotrophic axis deficiency and the last 4 patients had 3 axis insufficiency (corticotrophin, thyrotropin and gonadotrope). Although hypophysitis was biochemically reversible in 6 out of 59 patients, MRI pathological findings persisted in 5 of them even after pituitary-axes restoration after a median follow-up 37 months.

Conclusion: An abnormal MRI was found in 49 % (29/59) of patients with ICI-induced hypophysitis. Microadenoma and empty sella were the commonest findings (28% of the cases). In some cases, MRI abnormalities persisted even after restoration of the pituitary axes.