RESUMO
OBJECTIVE: To investigate the association of expression of Cat V with the clinicopathologic variables of myasthenia gravis (MG) in patients with thymoma. METHODS: Seventy-eight patients with thymomas were involved. Immunohistochemical method was adopted in investigating the protein expression of Cat V in the thymomas and thymic tissues adjacent to thymomas. RESULTS: The protein of Cat V could be detected in both thymomas and thymic tissues. And the cortex was the main expressive domain of Cat V in thymus. The positive ratio of Cat V expression in thymoma was significantly increased in patients with MG, compared with that in patients without MG (82.50% vs 26.33%, P < 0.01), and similar results were observed in thymic tissues adjacent to tumors (77.50% vs 31.58%, P < 0.01). Analysis on the relationship of the clinical subtypes of MG with expression of Cat V revealed that the positive ratio in type II (92.00%) and type III (83.33%) was much higher than that in type I (55.56%) (P < 0.05). The expression of Cat V was significantly raised in the epithelial-rich and mixed cell thymomas when compared with that in the lymphocyte-rich ones. No statistically significant difference was found on the variables such as perioperative myasthenic crisis, sex or age of patient, duraton of sickness and expression of Cat V. CONCLUSION: The overexpression of Cat V in thymomas may be associated with MG.