Although CT is widely accepted as the primary modality for detecting mediastinal lymphadenopathy, chest radiography is generally the initial radiographic investigation performed. On a normal lateral chest radiograph (Fig. 10A), the aortic arch and right and left pulmonary arteries are visualized in an “inverted horseshoe” configuration.³⁴ In the presence of subcarinal lymphadenopathy (Figs. 10B, C), the inferior portion of the “horseshoe” fills in.³⁴ The lymphadenopathy appears as a mass posterior to the bronchus intermedius and inferior to the tracheal bifurcation, completing the rounded hilar “doughnut” density.^34,35