Surgery for thymic tumors

Myasthenia gravis and thymoma. Evaluation of 41 patients

We evaluated the epidemiological, clinical, laboratory and therapeutical aspects of 41 patients with thymomatous myasthenia gravis. Thirty five patients (85.36%) were submitted to thymectomy. Follow-up ranged from two to 18 years. Diagnosis of thymoma was based upon clinical investigations and CT scan of the anterior mediastinum and in 11 patients supported by immunological tests of anti-striated muscle antibodies with a positive result in more than 80% of cases. Histopathologic examination of all thymomectomized patients confirmed the diagnosis of thymoma. There was a significant predominance of benign over malignant thymoma. Occurred higher prevalence of male patients and of patients over 40 years of age. The therapeutical strategy to control myasthenic clinical findings was the same as that for non-thymomatous myasthenia gravis. The corticosteroids associated to cytotoxic drugs were less often used. Radiotherapy of the anterior mediastinum was more often used in patients having invasive tumors submitted to surgery or not. With regard to survival and control of myasthenia gravis, especially in younger patients and in those submitted to early surgery, results of treatment were surprisingly favorable.

Combination chemotherapy with cyclophosphamide, adriamycin, and vincristine in malignant thymoma and myasthenia gravis

Malignant thymoma (MT) is a rare tumor that is often associated with myasthenia gravis (MG). This tumor is considered resistant to chemotherapy. We had the opportunity to treat five patients with MT with cyclophosphamide 800 mg/m2, Adriamycin 50 mg/m2, and vincristine 1.4 mg/m2 (CAV) in cycles of 21 days. Two patients with MG that was resistant to antimyasthenic drugs immediately responded to this combination. One patient with only MT had a complete response, and two patients with only MT had a partial response. Two out of the five patients are still alive and free of disease. Two patients died of disease, and one died from a neutropenia-induced respiratory tract infection. It is concluded that this combination chemotherapy is active in MT and MG and deserves additional trials.

Thymoma. The most common anterior mediastinal mass

Thymomas may be discovered during routine evaluation, through reported symptoms, or increasingly, during evaluation for myasthenia gravis. Histologic details of these tumors have little bearing on prognosis or evaluation of malignant potential. Malignancy is determined by evidence of invasion through the tumor capsule at surgery or of distant spread. Complete surgical excision is the mainstay of therapy for both benign and malignant thymoma. Biopsy of anterior mediastinal masses via mediastinoscopy should be avoided because of the risk of violating the thymoma capsule. If the capsule is surgically violated or extracapsular invasion is present, postoperative radiation therapy is indicated.

Recurrence of thymoma: clinicopathological features, therapy, and prognosis

Factors influencing the recurrence or persistence of thymoma after therapy were investigated in 127 patients with thymoma, including 75 with thymoma and myasthenia gravis. The rate of recurrence or persistence was 19% (24 of 127 patients) overall, 11% (8 of 75 patients) in myasthenic thymoma, and 31% (16 of 52 patients) in nonmyasthenic thymoma. The more advanced the clinical stage, the higher the rate of recurrence or persistence. The recurrence/persistence rate for patients with the same clinical stage was higher in those with nonmyasthenic thymoma (8% in Stage I, 11% in Stage II, 36% in Stage III, and 75% in Stage IV) than in those with myasthenic thymoma (0 in Stage I, 13% in Stage II, 18% in Stage III, and 20% in Stage IV). The prognosis for patients having subtotal resection of tumor was good in myasthenic thymoma (recurrence/persistence rate, 17%) in contrast with nonmyasthenic thymoma (recurrence/persistence rate, 78%). These results suggest that nonmyasthenic thymoma is more malignant than myasthenic thymoma. Postoperative radiotherapy was effective in preventing the recurrence or persistence of thymoma after therapy.

Invasive thymoma with myasthenia gravis

In 261 surgically treated patients with myasthenia gravis (MG), 26 had an invasive thymoma and 49 had a noninvasive thymoma. Invasive thymoma was seen in 41% of thymomatous MG patients older than 40 years of age, and 28% in patients younger than 40 years of age. Of 19 patients who underwent total or subtotal thymothymomectomy accompanied by irradiation (4000 rad), 17 were still alive on an average 6.5 years after surgery. The deterioration of MG by the irradiation was observed in 7 of 20 irradiated cases. Thus, postoperative irradiation is effective but should be done with attention to the deterioration of MG. The prognosis of MG in patients with an invasive thymoma was poorer than that in patients with a noninvasive thymoma.

Transcervical thymectomy for thymoma in myasthenia gravis

The results of thymectomy performed through a transcervical approach in 37 myasthenic patients with thymomas is reported and compared with results in 97 patients who had thymomas removed through a transsternal approach. In 29 of the former patients the thymomas were unsuspected and found at the time of thymectomy, and in 8 a preoperative chest roentgenogram was suspicious for the presence of a tumor. In the transcervical group there were only 4 invasive thymomas, while in the transsternal group there were 32. In the transcervical group there was no evidence of recurrence in the patients with unsuspected thymomas, and one recurrence in the group with suspected thymomas. In the transsternal group eight patients had known recurrence or persistent disease. The transcervical approach seems appropriate for the removal of small thymomas discovered at the time of thymectomy or suspected from the preoperative work-up.

Thymoma: clinicopathologic features, therapy, and prognosis

We have treated 40 patients with thymoma. All the 18 with benign thymoma were treated with resection alone and none had a tumor recurrence or died from disease-related causes. Postoperative survival in this group ranged from 2 months to 14 years. Of the 22 patients with malignant thymoma, 2 underwent total resection, 10 partial resection and 10 were non-resectable. Fifteen of the 20 patients with non-resectable and partially excised thymomas were given radiotherapy. The cumulative 5- and 10-year survival rate of irradiation treated patients was 45.6%, and 34.4%, respectively. Of 6 non-irradiated patients, only one who underwent complete excision of tumors survived for more than 10 years, and 5 died within 3 years after treatment. Based on our findings we suggest that all patients with malignant thymoma, irrespective of the extent of surgical treatment, should be given postoperative irradiation.

Thymomas in patients with myasthenia gravis

The records of 141 patients with myasthenia gravis who had thymomas were reviewed. In this series there were 69 noninvasive tumors and 52 invasive tumors. The five year survival for all patients was 60%, with the invasive group demonstrating a poorer prognosis than the noninvasive. The remission rates for the whole group (both invasive and noninvasive) of myasthenics was quite low (7%). Although the overall survival of this series of patients was relatively high, it is felt that by earlier diagnosis and a more aggressive surgical approach their prognosis will be even better.

Cervico-mediastinal thymic cyst with vocal cord paralysis

An unusual case of congenital cervico-mediastinal thymic cyst with vocal cord paralysis is presented together with a brief history and classification of these cysts. A discussion of thymic cyst symptomatology and the surgical approach to these lesions is included. Simple thymic cysts should be considered in the differential diagnosis of cervico-mediastinal masses, particularly in children and young adults.

Chemotherapy of invasive thymoma

Despite conventional therapy, including surgery and radiation, 5-year survival for invasive thymoma remains poor. Chemotherapeutic agents, including cisdiamminedichloroplatinum, prednisone, adriamycin and nitrogen mustard-vincristine-vinblastine-procarbazine, and bleomycin-adriamycin-CCNU-vincristine have produced short-term remissions. In view of the small number of cases seen in any one institution, a cooperative study to evaluate chemotherapeutic efficacy in malignant thymoma would seem worthwhile.

A « Pseudo-rosette » Thymoma in a 81-year-old Man

A very rare unsuspected thymic tumor is reported in a 81-year-old man. The tumor located in the mediastinum, 5, 5×3×2 cm in size, disclosed a lobular and/or alveolar histologic pattern, consisting of ovoid or elongated cells, mimicking epithelial and/or reticular cells. But the most remarkable histologic feature was the presence of «pseudo-rosettes» with single-layered, radially arranged cells encircling a web of silver- stainable fibrils. The last finding classified the tumor as a «pseudo-rosette » thymoma according to Lattes. This is the first report of such a tumor beyond the age of 80.