A case series of bilateral inferior petrosal sinus sampling using desmopressin for evaluation of ACTH-dependent cushing's syndrome in pediatric patients: insights from Iran.

Background: Pediatric Cushing Syndrome (CS) is rare and difficult to diagnose, especially when distinguishing ACTH-dependent subtypes. Bilateral inferior petrosal sinus sampling (BIPSS) is an essential but technically challenging procedure for this purpose. Because corticotropin-releasing hormone (CRH), the standard stimulant, has limitations, desmopressin is being explored as an alternative. This study assesses desmopressin-stimulated BIPSS for its diagnostic accuracy and tumor localization in pediatric CS within an Iranian cohort, addressing a gap in pediatric-specific diagnostic strategies and offering insights into the applicability of desmopressin in this context.

Methods: Four pediatric patients with inconclusive pituitary imaging and suspected Cushing's disease (CD) underwent BIPSS with desmopressin at Taleghani Hospital, Tehran, Iran, between August 2015 and March 2019. Sensitivity of BIPSS for CD diagnosis was assessed, and tumor localization accuracy was evaluated during surgery.

Results: Bilateral IPSS demonstrated a sensitivity of 100% for diagnosing CD in pediatric patients. However, accuracy for tumor lateralization was moderate, with only 50% concordance between BIPSS lateralization and surgical findings. Specifically, two out of four patients had correct lateralization confirmed during surgery, while one patient with left lateralization was consistent with hypophysectomy findings. These discrepancies highlight challenges such as anatomical and drainage variations that can lead to mislocalization.

Conclusion: Desmopressin enhances the sensitivity of BIPSS for diagnosing pediatric CD, presenting as a viable alternative to CRH stimulation. Despite high sensitivity, caution is advised when interpreting BIPSS results for tumor localization. Further research is needed to optimize diagnostic strategies for pediatric CS management.