P1.17-004 Extrapleural Pneumonectomy for Patients with Stage IVa Thymoma: Pathological Evaluation of Disseminated Pleural Nodules

Abstract

The optimal treatment method for thymoma with pleural dissemination remains controversial. We have performed a multimodality treatment including extrapleural pneumonectomy (EPP) for patients with stage IVa thymoma and pleural dissemination. There are few literatures investigating malignant behavior of disseminated nodules at the parietal and visceral pleura. Therefore, whether complete resection can be accomplished by EPP is not known. Our treatment strategy for those patients was induction chemotherapy with cisplatin, doxorubicin, and methylprednisolone (CAMP therapy), followed by thymectomy combined with EPP. We pathologically investigated parietal and visceral pleural nodules obtained by EPP in 8 patients with thymoma and pleural dissemination. The median age was 49 (31 to 60) years old. Seven patients had stage IVa disease and 1 had recurrent disease. Preoperative CAMP therapy was performed in 5 patients. Macroscopic complete resection was archived in all patients. Parietal pleural invasions by disseminated nodules were found in 6 patients, invasions to the diaphragm in 6 and visceral pleural invasions in 7. Invasions into the muscle layer of the diaphragm were discovered in 4 patients. Pathological complete resection (R0) was archived in all patients, and the 5-year recurrence free survival rate was 80.0%. EPP could be a successful complete resection and might be beneficial for patients with stage IVa thymoma and pleural dissemination. In those some patients, resection of the muscle layer of the diaphragm is needed to obtain R0.