Endocrine Abstracts

Introduction: Double and multiple pituitary adenomas (PAs) are rare in patients with Cushing’s disease. If two PAs are found, MRI cannot assess secretory activity. The claimed diagnostic effectiveness of inferior petrosal sinus sampling (IPSS) ranges from 82 to 100% across various studies. Yet, this procedure has limitations in everyday clinical practice. Thus, more clinical data on these lesions and possible advanced yet simpler diagnostical procedures are needed, as treatment options are dependent on precise clinical diagnoses.

Case report: We present a 27-year-old patient who was referred to the endocrinology clinic for obesity treatment and elevated values of serum cortisol (589 nmol/l (ref. 171-536)) and urine cortisol (687 nmol/dU (ref. 100-379)). He noticed the roundness of his face, an increase in anxiety requiring therapy, purple stretch marks around the navel, and gained about 6-7 kg, despite regular physical activity. Due to excessive body mass (BMI 31.46 kg/m²), liraglutide was introduced and an endocrinological workup was performed. In the overnight and low-dose dexamethasone suppression test no suppression occurred and ACTH values of 9.8 pmol/l were recorded indicating Cushing disease. The initial MRI of the pituitary gland was performed and showed no abnormalities, as well as the CT of the thorax and pelvis excluding visible ACTH-producing tumors. In addition, mildly increased values of IGF-1 were recorded with no clinical implication since mildly elevated IGF-1 in Cushing’s disease does not imply pathological growth hormone (GH) excess. To distinguish between ectopic ACTH and Cushing disease IPSS was performed, revealing the ACTH ratio of the right petrous sinus and periphery significantly greater than 2, while on the left side, it was below 1 confirming the diagnosis of Cushing’s disease. To control hypercortisolemia, ketoconazole was introduced into therapy. A control MRI of the pituitary gland was performed after 3 months, now exposing two potential pituitary lesions (in the caudolateral part diameter of 2.5 mm and the posterolateral part a diameter of 3 mm), which could indicate ACTH secreting microadenomas. Therefore; ¹⁸F-FET PET is planned to localize corticotroph microadenoma.

Conclusion: The diagnostical challenges in differentiating Cushing syndrome never cease to exist. In this case report we intended to increase awareness of the need to explore the possibility of the presence of two distinct corticotroph tumours. Initial studies using ¹⁸F-FET-PET/MR suggest a high predictive value for localizing corticotroph microadenomas posing a promising method in the differentiation of Cushing’s disease.