P38: Reoperation for recurrent thymoma: a single-center experience from Nanchang

Background: To analyze causes for recurrence of thymoma after primary operation, explore the relation between thymoma and myasthenia gravis, and summarize surgical treatments for recurrent thymoma.

Methods: Five cases of recurrent thymoma were re-operated. At primary operation all patients were complicated with myasthenia gravis, including one type I, one type IIa, one type IIb and two type C thymoma according to Osserman classification. Upon reoperation, none of these patients manifested with myasthenia gravis; and pyridostigmine bromide was withdrawn after 1 to 6 years since symptoms of myasthenia gravis were totally relieved. Post-operatively histological diagnosis were made according to the WHO classification (primary operation: three type B2 case, one type B3 case and one type C case; reoperation: three type B2 case and two type C case) and the Masaoka system (three IIb case and two III case in both primary operations and reoperations). Among these recurrent cases, one case recurred diffusively in the left pleura, left lung and left ribs, with one positive lymph node (1/10); one case recurred in the right chest cavity and transferred to the left inferior lobe; one case recurred in the right chest cavity and the right inferior lobe; one case recurred in the mediastinum, left upper lobe and the pericardium; yet another case recurred in the mediastinum, the right chest cavity, right upper lobe, superior vena cava and brachiocephalic vein. Reoperation was carried out in all recurrent cases. Sternotomy was performed in one patient for resection of mediastinal tumor, pneumonectomy and replacement of brachiocephalic vein and superior vena cava with artificial blood vessel. Video-assisted thoracic surgery (VATS) was performed in two cases, namely, resection of mediastinal tumor, part of left upper lobe, pericardium and the left phrenic nerve and resection of part of right lower lobe and tumor in the right thoracic cavity. Left posterolateral thoracotomy for resection of part of left upper lobe, pleural tumor and invaded ribs was performed in one patient. Yet one patient was procedured for left lower lobectomy through posterolateral thoracotomy and resection of the recurrent thymoma via VATS in the right thorax.

Results: One patient died of respiratory failure in the 14^th postoperative day. Two patients died of multi-organ dysfunction in the 25^th and 36^th postoperative month, respectively. Two patients survived and pyridostigmine bromide was withdrawn after the symptoms of myasthenia gravis were totally relieved 1 to 6 years post-operatively.

Conclusions: (I) We proposed that thymoma recurs mainly in forms of recurrence in situ and seeding in the chest cavity, instead of metastasis via lymphatic pathway; (II) recurrence of thymoma is highly related to histological types and pathological characteristics; (III) symptoms of myasthenia gravis in recurrent patients are not highly related to the severity of the recurrent thymoma; (IV) reoperation must be performed thoroughly without tissue fragments reserved, thoracic irrigation in the end of procedure can help elimination of those fragments. Chemotherapy should be implemented in patients diagnosed with thymoma of pathological type B2 and C. Regular CT scan can help early diagnosis of recurrence, which should be reoperated without delay.

Keywords: Thymoma; recurrence; reoperation