A corticotroph pituitary adenoma as the initial presentation of familial glucocorticoid deficiency

CONTEXT; Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive ACTH-resistance syndrome characterized by glucocorticoid deficiency in the absence of mineralocorticoid deficiency. Here, we report the case of a young woman with a corticotroph pituitary adenoma as the initial presentation of FGD.

A 15-year-old girl was referred to our institution for a 16 mm pituitary adenoma associated with glucocorticoid deficiency. Clinical and biological features were evocative of FGD. DNA sequencing did not identify mutations in either the melanocortin 2 receptor (MC2R) or the MC2R accessory protein genes, indicating type 3 FGD. Despite adequate glucocorticoid replacement, plasma ACTH levels remained increased and pituitary magnetic resonance imaging (MRI) showed a progression of the tumour size resulting in optic chiasm compression with intra-tumoural haemorrhaging. When the patient was 26 years old, it was decided that she would undergo transsphenoidal surgery. The histomorphological analysis identified a well-individualized pituitary adenoma immunoreactive for ACTH. The proband's sister also exhibited type 3 FGD associated with pituitary hyperplasia upon MRI.

This case highlights the relationship between FGD and hyperplasia of ACTH-producing cells, potentially leading to histologically proven pituitary corticotroph adenomas. This observation raises the question of the pituitary MRI's significance in the follow-up of FGD.