Incidentally diagnosed superior vena cava narrowing prompted by screening mammography.

An adult woman with a prior history of treated non-Hodgkin's lymphoma presented for screening mammography, which incidentally demonstrated dilated veins throughout the bilateral breasts. Concern for a superior vena cava stenosis or obstruction was raised despite the patient being asymptomatic; the patient underwent further imaging with chest CT, which revealed focal stenosis of the superior vena cava, attributed to fibrosis secondary to prior radiation therapy. Superior vena cava syndrome (SVCS), the spectrum of disease caused by superior vena cava narrowing or obstruction, requires prompt investigation given its association with intrathoracic malignancy, primary lung cancer and poor outcomes. This report explores the benign and malignant causes, signs and symptoms, preferred investigations, and treatment of SVCS. This case highlights the potential importance of screening mammography in revealing unexpected ancillary diagnoses, especially in high-risk patients.