21st February 2025

Investigation of mediastinal masses

Investigations depend on the likely differentials, for example:

• Suspected lymphoma: full blood count, blood film and flow cytometry
• Suspected thoracic thyroid tissue: thyroid function tests
• Suspected germ cell tumour: tumour markers including LDH, alpha fetoprotein, beta-HCG. beta-HCG and LDH may be raised in either seminomatous or non-seminomatous tumours, whereas AFP will only be raised in non-seminomatous tumours
• Suspected thymic mass: anti-acetylcholine receptor (AChR) antibodies to evaluate for myasthenia gravis

CT can give information as to the location and composition of a mediastinal mass and may also be helpful in planning for a biopsy.

Ultrasound of the testes should be considered in men presenting with a mediastinal mass to look for evidence of a germ cell tumour.