# Mometasone Furoate–Induced Iatrogenic Cushing's Syndrome and Secondary Adrenal Insufficiency: A Case Report

## TL;DR

A child developed Cushing's syndrome and adrenal insufficiency from long-term nasal steroid use, highlighting the need for pediatricians to monitor such treatments.

## Contribution

This case report highlights the rare but serious risk of iatrogenic Cushing's syndrome from prolonged intranasal corticosteroid use in children.

## Key findings

- An 8-year-old girl developed Cushingoid features and adrenal insufficiency after prolonged intranasal corticosteroid treatment.
- Endocrine testing showed undetectable cortisol levels, indicating adrenal suppression.
- Hydrocortisone replacement therapy was required, and close pediatric follow-up is recommended for long-term steroid users.

## Abstract

Intranasal corticosteroids (INCS) are widely used to treat allergic rhinitis and nasal obstruction. While their safety profile is generally well established, both local and systemic side effects can occur. While it is well-known that a chronic exposure to systemic glucocorticoid treatment could determine Cushing's syndrome (CS) and suppression of the hypothalamic–pituitary–adrenal (HPA) axis, there is less awareness when the administration is topical or intranasal. We report the case of an 8-year-old Caucasian girl who developed Cushingoid features following prolonged INCS treatment—initially with betamethasone and subsequently with mometasone furoate. Endocrine testing revealed undetectable baseline and after stimulation cortisol levels, suggesting a condition of adrenal insufficiency secondary to the prolonged glucocorticoid exogenous administration. Temporary hydrocortisone replacement therapy was required. Even if extremely rare, pediatricians should be aware that high-dose and long-term nasal steroid administration may cause iatrogenic CS, as well as systemic glucocorticoid treatment. Clinical features are characterized by the complications of glucocorticoid excess and by the potential life-threatening complications of adrenal insufficiency. Pediatric follow-up should be scheduled during the prolonged steroid treatment and at discontinuation, with prompt referral to a Pediatric Endocrinologist if signs and symptoms of CS (or adrenal insufficiency) are noticed.