# Ectopic Adrenocorticotropic Hormone (ACTH) Syndrome Caused by Mediastinal Carcinoma: A Report of a Rare Case

## TL;DR

A rare case of a mediastinal tumor causing Cushing's syndrome is reported, highlighting its difficulty in diagnosis and poor outcome.

## Contribution

This paper presents a rare clinical case of ectopic ACTH syndrome caused by a mediastinal carcinoma.

## Key findings

- A 37-year-old man presented with Cushingoid features and elevated ACTH due to a mediastinal neuroendocrine carcinoma.
- Despite treatment, the patient's prognosis was poor, with death occurring within months.
- The case emphasizes the rarity and diagnostic challenges of mediastinal ectopic ACTH syndrome.

## Abstract

Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a rare cause of ACTH-dependent Cushing's syndrome, exceptionally due to mediastinal carcinoma. We report a 37-year-old man with Cushingoid features, hypercortisolism, and elevated ACTH. Imaging revealed an unresectable anterior mediastinal mass; biopsy confirmed high-grade neuroendocrine carcinoma. Despite medical therapy and chemoradiotherapy, the outcome was fatal within months. This case highlights the rarity, diagnostic difficulty, and poor prognosis of mediastinal EAS.