Endocrine Abstracts

JOINT169

Introduction: Rathke’s cleft cyst (RCC) is a benign, non-neoplastic lesion located in the sellar and suprasellar region of the brain, with a prevalence of 12-33% of cases. It constitutes a remnant of Rathke’s pouch - an embryonic precursor of the pituitary gland. While most RCCs appear asymptomatic, headaches, visual disturbances, mass effect-related hypopituitarism, and hyperprolactinemia due to the "stalk effect" phenomenon may occur. Arginine vasopressin deficiency (AVP-D), characterized by impaired hypothalamus/posterior pituitary vasopressinergic neurons, resulting in dysfunction in AVP synthesis, typically does not represent the clinical picture of an RCC patient.

Case report: A 25-year-old female with a history of severe headaches (NRS 5-9 points) was referred to the Department of Endocrinology for hormonal evaluation of a sellar lesion visualized in an outpatient head magnetic resonance imaging (MRI). She had a history of polyuria, polydipsia, and unintentional weight gain (10kg in 2-3 months). On physical examination, the patient was in general good condition, without features of endocrine stigmatization. Hormonal evaluation revealed normal prolactin levels (triplicate determinations), including after dilution, and preserved appropriate function of the pituitary tropic axes. Additional testing indicated decreased urine specific gravity (USG) and osmolality, increased plasma osmolality, which, along with polydipsia and polyuria (7700 mL/day), led to the suspicious of AVP-D. Other clinical causes and the drug effect have been excluded. Desmopressin (DDAVP) treatment was initiated, the dosage was set individually according to symptoms and plasma osmolality. A follow-up head MRI identified significant progression of the sellar mass dimensions - 14 (CC) × 12 (AP) × 17 (DB) mm, high-intensity in T1 and T2-weighted images, adhesion to the medial cavernous sinuses’ walls and modeling of the optic chiasm. On ophthalmological evaluation, the patient had no significant visual field abnormalities. She was consulted neurosurgically and, upon informed consent, qualified for surgery. In hydrocortisone protection, transsphenoidal endoscopic resection of the pituitary lesion was performed. The procedure was uncomplicated. A normal postoperative image with complete resection was confirmed in head computer tomography and MRI. Clinically, the patient did not develop cerebrospinal fluid leakage. Histopathological verification revealed RCC. In the postoperative evaluation (performed without DDAVP usage), the patient presented adequate urine output, with normal USG and plasma osmolality.

Conclusions: Given the concerns about determining the appropriate management of mildly symptomatic RCC, it seems crucial to consider AVP-D as a clinical manifestation.