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Table 1 Pathological classification and clinical staging of thymoma

From: Association between thymoma and persistent hypothermia: a case report

WHO Thymoma classification 5-year survival rate (%)
Type A 100
Type AB 93
Type B1 89
Type B2 82
Type B3 71
Masaoka Clinical Stage Macroscopic or Microscopic Features
I Encapsulated tumour. No evidence of capsule invasion
IIa Macroscopic invasion into surrounding fatty tissue or mediastinal pleura
IIb Microscopic invasion into the capsule
III Macroscopic invasion into neighbouring organs including pericardium, major vessels or lung.
IVa Pleural or pericardial dissemination.
IVb Lymphogenous or haematogenous metastasis.