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Table 1 Classification of thymomas according to Masaoka-Koga stage [14]

From: A single-center experience: management of patients with thymic epithelial tumors

Stage

Masaoka-Koga staging system

I

Grossly and microscopically completely encapsulated tumor

II a

Microscopic transcapsular invasion

II b

Macroscopic invasion into thymic or surrounding fatty tissue, or grossly adherent to but not breaking through mediastinal pleura or pericardium

III

Macroscopic invasion into a neighboring organ (i.e., pericardium, great vessel, or lung)

IV a

Pleural or pericardial metastases

IV b

Lymphogenous or hematogenous metastasis