Commonest mass in the middle mediastinum is –

"Lymphadenopathy is by for the most common middle mediastinal mass". "The most common middle mediastinal mass is adenopathy". "Lymphadenopathy is the most common middle mediastinum mass".                   You should keep in mind that, though, the most common middle mediastinal mass is lymph nodes enlargement, duplication congenital cysts (Bronchogenic cysts, esophageal duplication cysts) are the most common middle mediastinal masses in children. Most common anterior mediastinal mass                  →              Thymoma Most common middle mediastinal mass                   →               Lymphadenopathy Most common middle mediastinal mass in children   →               Congenital duplication cysts  Most common posterior mediastinal mass                →               Neurogenic tumors  Overall most common mediastinal mass                  →               Neurogenic tumors    Note - Neurogenic tumors constitute 20% and thymomas constitute 19% of all the mediastinal masses.