Cystic lesion of the thymus. An occasionally malignant cervical and/or anterior mediastinal mass.

Between 1965 and 1982, we treated 46 patients with cystic lesions of the thymus. Thirty patients had anterior mediastinal cysts, nine had cysts which were large enough to be both cervical and mediastinal, and seven had cervical cysts. The majority (40/46) presented with asymptomatic masses. Six patients presented with distinct complaints: dysphagia (four patients), hoarseness owing to vocal cord paralysis (one patient), and cervical pain (one patient). All six had benign thymic cysts. The diagnosis of a cystic mass was established prior to operation by ultrasonography and computed axial tomography in our last three patients. These two techniques delineated the capsule and the central fluid in those three cases. All 46 patients had the mass resected without mortality or significant morbidity, except for resection of the phrenic nerve in one patient with malignant cystic thymoma. Cervical cysts were excised through cervical incisions. Cysts located in the anterior mediastinum and cervical-mediastinal cysts required median sternotomy or right thoracotomy for successful resection. Pathological examination showed that 39 patients had benign thymic cysts, three had benign cystic thymoma, two had malignant thymoma, one had a seminoma arising in the thymus, and one had a lymphoblastoma. We believe that a cystic thymic mass which can be detected by ultrasonography and computed tomography, although usually benign, does not eliminate the possibility of malignancy, and resection, therefore, is indicated.

Management of patients with malignant thymoma.

This report documents the results of therapy in 23 patients treated for malignant thymoma between 1944 and 1979. Of the group, 22 patients had neoplasms which invaded mediastinal structures; six had distant metastases. Four patients had myasthenia gravis and one had erythroid hypoplasia associated with collagen vascular disease. No deaths were associated with primary therapy, which included an operative procedure in all cases. Follow-up ranged from 4 months to 18 years (mean 5.63 +/- 1.03 years, SEM). Fifteen patients died, with postoperative survival times ranging from 4 months to 18 years (mean 3.8 +/- 1.27 years). Five patients were alive without recurrence from 3 to 11 years postoperatively (mean 6.8 +/- 1.36 years), and three patients were alive with recurrence or distant metastases from 4 to 17 years postoperatively (mean 10.75 +/- 2.66 years). Differences in survival on the basis of tumor cell type were not statistically significant. Therapeutic groups were analyzed for 5 year survivors, tumor deaths within 5 years of therapy, deaths due to other causes, deaths due to tumor after 5 years, those presently alive, and longest known survivor. The data suggest that complete surgical excision offers the best chance of long-term survival when compared to partial resection plus irradiation (p less than 0.05). No statistical significance could be demonstrated between the groups who had complete resection with versus without postoperative irradiation. There also was no statistically significant difference between the group of patients receiving irradiation following partial excision of most of their tumor and the group receiving irradiation following only biopsy of the lesion. This observation suggests there is no value in so-called "debulking procedures" and suggests that irradiation may be of value in local control of thymoma. Perpetual surveillance is necessary since late recurrence is common.