21st February 2025

A 45-year-old woman presents with slurred speech, diplopia and generalised weakness.

A 45-year-old woman presents with slurred speech, diplopia and generalised weakness. On examination, she is noted to have bilateral ptosis and fatigable muscle weakness. She has a history of hypertension and polycystic ovaries. A chest X-ray is performed, which demonstrates a wide mediastinum, so a CT chest is requested, which demonstrates a mediastinal mass. 

What is the most likely diagnosis of the mediastinal mass?

Select the SINGLE most appropriate option from the list below. Select ONE option only.