POMC and thymoma: These results indicate that patients in the POMC group were more likely to have a more advanced MGFA stage (P = 0.003), POA (P = 0.016), a preoperative myasthenic crisis (P = 0.031), a thymoma (P = 0.006), an ectopic thymus (P = 0.028), use of a higher dose of PYR (P < 0.001), and postoperative pneumonia (P < 0.001).