MON-473 Autoimmune Adrenalitis and an Adrenal Tumor in a 17-Year-Old Girl With Elevated 17-Hydroxyprogesterone and Secondary Amenorrhea

Abstract Disclosure: L. Walfish: None. L. Feldman: None. O. Ajise: None. J.A. Rivera: None. Background: Adrenal tumors can be seen in inadequately treated patients with congenital adrenal hyperplasia (CAH), thought to result from chronic adrenocorticotrophic hormone (ACTH) overstimulation. In patients with CAH, a characteristic finding of poor control is elevated 17-hydroxyprogesterone (17-OHP). Similarly, it has been documented that some non-secreting adrenal adenomas can be 21-hydroxylase deficient and, therefore, also produce 17-OHP under ACTH stimulation. Scarce data exists describing autoimmune adrenalitis associated with adrenal masses and elevated 17-OHP. Case Presentation: A previously healthy 17-year-old female presented to her primary care physician for a 1-year history of secondary amenorrhea after discontinuing oral contraceptives. Progesterone challenges were negative. Notable laboratory investigations included an elevated 17-OHP at 117 nmol/L (ref. 0.6-8.0nmol/L). An abdominal pelvic ultrasound revealed a 2.7 cm right adrenal tumor. Upon presentation to endocrinology, history and physical examinations showed no signs or symptoms of adrenal hormone overproduction. Further biochemical assessment of adrenal hyperfunction was also negative. Other than an elevated renin at 464.8 ng/L (ref. 3.3-6.1) with a low normal aldosterone, the rest of her hormonal work up showed no abnormalities. Genetic analysis showed no mutation in a 12-genes CAH panel. On further questioning, the patient admitted to salt craving, morning nausea, fatigue, and spontaneous skin darkening in comparison to her twin sister. A morning cortisol resulted at 76 nmol/L (ref.120-535), ACTH > 440pmol/L (ref. 1.6-13.9), with presence of adrenal autoantibodies. She was diagnosed with autoimmune primary adrenal insufficiency (AI) and started on hydrocortisone and fludrocortisone replacement. An abdominal MRI demonstrated a 2.5x1.4x1.8cm right adrenal, well-circumscribed tumour, isointense in T2, hypointense in T1, with no loss of signal on the out-of-phase T1 sequences, in keeping with a lipid-poor lesion. A PET scan demonstrated the mass to be FDG avid at 19.4 SUV. The patient is currently waiting for laparoscopic right adrenalectomy. Conclusion: This case highlights a potential relationship between adrenal masses and primary autoimmune adrenalitis that has not been described before. Most reported cases of this type of co-occurrence have been related to adrenal lymphoma or CAH. The elevated plasma 17-OHP in our case is unusual and is suspected to originate from the adrenal tumor’s expected decreased 21-hydroxylase expression. Such deficiency would otherwise go unnoticed but has become evident under strong ACTH stimulation from the primary AI. The strong ACTH stimulation may also explain the high FDG uptake, contrasting with surrounding ongoing adrenalitis. Nevertheless, surgical removal is indicated given the lipid-poor nature of the lesion. Presentation: Monday, July 14, 2025