Pituitary stalk thickening in pediatric patients: an underrecognized diagnosis?

Objective: Pituitary stalk thickening (PST) is a rare condition in pediatric patients. Data on PST in Latin American pediatric populations are scarce. The aim of this study was to characterize a comprehensive cohort of pediatric patients diagnosed with PST in Chile between 2020 and 2022. Subjects and methods: Retrospective review of medical records from 2020 to 2022 of patients under 18 years old diagnosed with PST, defined as a pituitary stalk width ≥ 3 mm at the pituitary insertion and/or ≥ 4 mm at the optic chiasm. A literature review was also performed to compare the identified cases with previously published ones. Results: Nine patients with PST were identified. Their mean age at diagnosis was 10.36 years (range 2.4-17 years). The patients' main manifestations were polydipsia and polyuria (100%) and poor growth (77.8%). Eight patients had germ cell tumors, while one patient had Langerhans cell histiocytosis. At the time of diagnosis, all patients had arginine vasopressin (AVP) deficiency, along with a deficiency in at least one anterior pituitary hormone. Germ cell tumor markers were negative in all patients. A biopsy-confirmed diagnosis was obtained in all cases. Four patients required a second biopsy. The frequency of PST due to germ cell tumors was four patients/year during the study period, which is twice the expected frequency in Chile. Conclusion: This study, characterizing the largest cohort of pediatric patients with PST in Latin America, found germ cell tumors to be the main etiology of this condition. It is important to focus diagnostic procedures on obtaining a correct diagnosis and promptly initiating appropriate treatment in patients with PST. Regional cooperation is essential for gathering data from larger cohorts to enhance our understanding of pediatric PST and improve patient outcomes.