Normotensive primary aldosteronism in a patient with myasthenia gravis: a localization diagnostic conundrum unraveled by Ga-pentixafor PET/CT - a case report with review of literature.

Purpose: While primary aldosteronism (PA) is typically screened in hypertensive patients, normotensive PA remains underrecognized, especially in complex cases where standard diagnostic approaches fail. We present a challenging case of normotensive PA complicated by myasthenia gravis (MG) requiring chronic glucocorticoids, which interfere with conventional cortisol-based adrenal venous sampling (AVS) interpretation. This case highlights the pivotal role of Ga-pentixafor PET/CT as an innovative alternative for subtype differentiation in such complex scenarios.

Methods: A 30-year-old normotensive woman with MG (on long-term glucocorticoids) was incidentally found to have a left adrenal adenoma. Biochemical testing confirmed PA (elevated ARR, positive captopril challenge test and saline infusion test). Due to glucocorticoid interference with AVS interpretation, Ga-pentixafor PET/CT was utilized for precise localization. We further reviewed literature on alternative diagnostic strategies for PA when conventional cortisol-based AVS interpretation is compromised.

Results: Ga-pentixafor PET/CT successfully localized the aldosterone-producing adenoma, guiding laparoscopic adrenalectomy. Postoperatively, the patient achieved complete biochemical remission (normalized ARR and potassium). To our knowledge, this is the first reported use of Ga-pentixafor PET/CT for PA subtype diagnosis in a glucocorticoid-dependent normotensive patient, offering a paradigm for similar challenging cases.

Conclusions: For PA patients with confounding factors affecting cortisol-based AVS interpretation (e.g., chronic glucocorticoid use), Ga-pentixafor PET/CT emerges as a robust non-invasive alternative for accurate subtype differentiation. This case provides a novel diagnostic framework for complex PA presentations, advocating for tailored imaging strategies to overcome traditional limitations.