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In medicine (oncology), thymoma is a neoplasm of the thymus. It is a rare disease, best known for its enigmatic association with the neuromuscular disorder myasthenia gravis. There are benign and malignant forms, which present similarly. more...

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Signs and symptoms

  • 33%-50% is detected accidentally on routine X-rays of the chest.
  • 33% presents with complaints due to compression of surrounding structures by the expanding tumor:
    • Vena cava superior syndrome (compression of the upper caval vein)
    • Dysphagia (trouble swallowing)
    • Cough, chest pain
  • A final 33% has autoimmune symptoms; thymomas in these are usually benign. The best known is myasthenia gravis, of which 25-50% is associated with a thymoma. Some others are: pure red cell aplasia and Good's syndrome (thymoma with combined immunodeficiency and hypoimmunoglobulinemia G).
    • Rare associations that have been reported are: acute pericarditis, Addison's disease, agranulocytosis, alopecia areata, ulcerative colitis, Cushing's disease, hemolytic anemia, limbic encephalopathy, myocarditis, nephrotic syndrome, panhypopituitarism, pernicious anemia, polymyositis, rheumatoid arthritis, sarcoidosis, scleroderma, sensorimotor radiculopathy, stiff person syndrome, systemic lupus erythematosus and thyroiditis.

Malignant thymomas can metastasize, generally to pleura, kidney, bone, liver or brain.


When a thymic pass is identified, the diagnosis is achieved with histology (obtaining a tissue sample of the mass). When a thymoma is suspected, a CT/CAT scan is generally performed to estimate the size of the tumor, and can be biopsied with a CT-guided needle. Although there is a risk of pneumomediastinum, mediastinitis and the risk of damaging the heart or large blood vessels.

The tumor is generally located inside the thymus, and can be calcified. Increased vascular enhancement can be indicative of malignancy, as can be pleural deposits.

If the suspicion is real, some blood tests are often performed to gain an appreciation of associated problems or possible spread. These include: full blood count, protein electrophoresis, antibodies to the acetylcholine receptor (indicative of myasthenia), electrolytes, liver enzymes and renal function.

The final diagnosis is made by removing the thymus. Pathological investigation of the specimen will reveal if the tumor was benign or malignant.


Thymomas originate from the epithelial cell population in the thymus. Many subtypes are recognised, some of which have a better- or worse-than-general prognosis.


Men and women are equally affected. The main age for thymomas is 30-40, although cases have been described in every age group.


Surgery is the mainstay of treatment. If the tumor was benign and was removed in its entirety, no further therapy is necessary. Malignant tumors may need additional treatment with radiotherapy, or sometimes with chemotherapy (cyclophosphamide, doxorubicin and cisplatin).


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Videothoracoscopic resection of stage II thymoma : prospective comparison of the results between thoracoscopy and open methods
From CHEST, 10/1/05 by Yu-Jen Cheng

Study objectives: Although videothoracoscopic (VTS) resection of Masaoka stage I thymoma has been reported to be a less invasive method than open thoracotomy and to achieve a comparable surgical outcome, the usefulness of this method in the treatment of stage II thymoma has not yet been prospectively evaluated. We therefore compared the VTS and open (median sternotomy) methods to see whether VTS resection could be used as successfully to treat stage II thymoma disease.

Design, setting, and patients: Patients (11 women and 11 men) with stage II thymoma were prospectively enrolled between November 1999 and September 2004. Of these, 12 patients (the VTS group) underwent tumor resection using a three-port endoscopic technique, and 10 patients (the open group) underwent tumor excision using a standard sternotomy approach. The diagnosis of all resected thymoma lesions and their stage were confirmed by histopathogic examination.

Measurements and results: Neither group experienced mortality or any major morbidity. The difference in mean age ([+ or -] SD) between the VTS and open groups (40.2 [+ or -] 16.3 years and 47.7 [+ or -] 8.5 years, p = 0.202); mean operation lime (193.3 [+ or -] 79.6 min and 207.5 [+ or -] 85.8 min, p = 0.692); mean duration of pleural drainage (4.2 [+ or -] 2.1 days and 4.6 [+ or -] 2.1 days, p = 0.702); and mean duration of postoperative hospital stay (6.8 [+ or -] 2.3 days and 8.9 [+ or -] 4.4 days, respectively; p = 0.157) were not statistically significant. However, mean intraoperative blood loss amounts were statistically different (119.2 [+ or -] 70.6 mL and 238.5 [+ or -] 110.2 mL, respectively; p = 0.006). During the mean follow-up period of 33.9 [+ or -] 19.7 months, all patients survived without sign of recurrence, and the mean survival time was not statistically significant (32.3 [+ or -] 22.0 months and 35.8 [+ or -] 17.5 months, respectively; p = 0.686).

Conclusion: Using careful and skillful technique, the VTS method is an effective treatment of stage II thymoma.

Key words: mediastinal neoplasms; minimally invasive surgery; thoracoscopy; thymoma; thymomectomy

Abbreviations: VATS = video-assisted thoracoscopic surgery; VTS = videothoracoscopy/videothorascopic


The occurrence rate of stage II thymoma ranges from 18 to 23% in all thymoma groups. (1,2) The surgical options are medial sternotomy, thoracotomy, and video-assisted thoracoscopic surgery (VATS). The sternotomy method is the preferred standard treatment. In some situations, thoracotomy is considered for ectopic thymoma. In recent years, VATS with or without a utility thoracotomy to excise the mediastinal thymic lesions has been reported as an effective treatment. (3-9) However, there is still no prospective comparison of thoracoscopy with open methods of treating Masaoka stage II thymoma. Therefore, VATS without a utility thoracotomy (videothoracoscopy [VTS]) was compared with open resection using medial sternotomy. We wanted to determine whether this VTS approach was an effective treatment for stage II thymoma.


Between November 1999 and September 2004, 73 cases of primary mediastinal lesions were resected with curative intent. Of these, 22 patients (11 women and 11 men) with Masaoka stage II thymoma were prospectively enrolled. Twelve of these patients underwent complete thymoma resection using a three-port endoscopic technique (VTS group). The other 10 patients underwent standard medial sternotomy to excise the thymoma (open group). Diagnoses of all resected lesions and their stage were confirmed by histopathologic examination.

All patients with suspected thymoma who were eligible for surgery were interviewed and informed about the VTS and open-surgery procedures. For the VTS method, three thoracoports were created for thoracoscopic inspection and instrument manipulation. The tumor was first dissected from the pericardial area and then upward toward the neck base. Injury to the phrenic nerve was strictly avoided. The thymic vein and other large vessels were clamped with endoclippers. Local lung invasion was wedge resected using an stapling device (Endo-GIA; US Surgical; Norwalk, CT) stapling device. If the freed mass was too large to be removed with a retrieval bag, removal would be accomplished by cutting the mass piece-by-piece in a double-layered bag. One chest tube (32F) was routinely retained after the operation. The procedure in the sternotomy group was conventional. All patients received adjuvant radiation therapy after the operation. The results were compared using the Student t test (independent samples) to determine the level of significant difference between the two groups.


There were no deaths or major complications in both groups and no conversion to thoracotomy in the VTS group. The mean age ([+ or -] SD) in the VTS and open groups (40.2 [+ or -] 16.3 years and 47.7 [+ or -] 8.5 years, respectively) was not statistically different (p = 0.202). Mean intraoperative blood loss amounts were significantly different in the VTS and open groups (119.2 [+ or -] 70.6 mL and 238.5 [+ or -] 110.2 mL, respectively; p = 0.006). The VTS and open groups also did not have significantly different mean operation times (193.3 [+ or -] 79.6 min and 207.5 [+ or -] 85.8 min, p = 0.692); mean duration of pleural drainage (4.2 [+ or -] 2.1 days and 4.6 [+ or -] 2.1 days, p = 0.702); and mean duration of postoperative hospital stay (6.8 [+ or -] 2.3 days and 8.9 [+ or -] 4.4 days, respectively; p = 0.157). During the mean follow-up period (33.9 [+ or -] 19.7 months; range, 5.2 to 63.5 months), all patients in both groups survived without sign of recurrence, and the mean survival time in the VTS and open groups (32.3 [+ or -] 22.0 months and 35.8 [+ or -] 17.5 months, respectively; p = 0.686) was not significantly different. Myasthenia gravis was present in six patients (50%) in the VTS group and six patients (60%) in the open group. In the VTS group, six patients had Masaoka thymoma stage IIa and six patients had stage IIb. In the open group, six patients had stage IIa and four patients had stage IIb. The difference in stage distribution between these two groups was not statistically significant (p = 0.658, one-way analysis of variance). The patient profile is summarized in Table 1.


VTS surgery with the advantages of small incision and rapid recovery offers a better-tolerated approach to treat mediastinal lesions. The objective of VTS and open surgical treatment of thymoma, with or without myasthenia gravis, is the complete removal of the tumor and all involved structures. (9,10) The resection extent is almost the same for both the VTS and transsternal approaches. (11) With the benefit of minimal invasiveness and acceptable resection extent, we consider that resection of thymoma by VTS meets both the anatomic and surgical requirements of successful treatment. The right thoracic approach is preferred, except in cases of obvious left-sided thymoma. (12)

The existence of thymoma is best detected by chest CT, with 85% sensitivity, 98.7% specificity, and 95.8% accuracy rate. (13) If the CT fails to detect great-vessel involvement or other intrathoracic metastasis, thoracoscopic resection of the entire lesion may be undertaken. Therefore, VTS resection of Masaoka stage II is not contraindicated when the entire tumor and the locally involved tissue can be removed. The careful manipulation of tumor tissue to avoid intrathoracic spreading is also important, and a two-layered retrieval bag is needed for piece-by-piece removal of a large mass.

The mean intraoperative blood loss amounts were statistically less in the VTS group, which means that the VTS approach is less invasive in treating stage II thymoma. The mean age, mean operation time, mean duration of pleural drainage, and mean duration of postoperative hospital stay were all not significantly different between these two groups. No significant decrease in the drainage time and hospital stay was found in the VTS group, but this may have been due to the small sample evaluated in this study. Operation time was similar in both groups, showing that an experienced thoracoscopist can perform the endoscopic procedure within an acceptable timeframe.

The adjuvant radiation therapy for stage II thymoma is widely advocated, but the evidence supporting it is controversial. (14) From the reports of Singhal et al (14) and Mangi et al, (15) adjuvant radiation therapy does not improve the prognosis of completely resected stage II thymoma. Therefore, the adjuvant radiation therapy used in our study is not considered to affect outcome.


This study has a limited number of cases because of its experimental intent, and follow-up duration is still not long enough. To our knowledge, this is the first prospective study on thoracoscopic resection of stage II thymoma. In careful and skillful hands, the thoracoscopic method can be performed in an effective way to treat stage II thymoma. The collection of more prospective data is needed to evaluate long-term effectiveness.

Manuscript received February 19, 2005; revision accepted March 9, 2005.


(1) Bergh NP, Gatzinsky P, Larsson S, et al. Tumors of the thymus and thymic region: I. Clinicopathological studies on thymomas. Ann Thorac Surg 1978; 25:91-98

(2) Nakahara K, Ohno K, Hashimoto J, et al. Thymoma: results with complete resection and adjuvant postoperative irradiation in 141 consecutive patients. J Thorac Cardiovasc Surg 1988; 95:1041-1047

(3) Landreneau RJ, Dowling RD, Castillo WM, et al. Thoracoscopic resection of an anterior mediastinal tumor. Ann Thorac Surg 1992; 54:142-144

(4) Peliukhovskii SV. Application of videothoracoscopy in surgical treatment of thymoma and histological characteristics of the tumor[in Japanese]. Klinicheskaia Khirurgiia 2001:54-55

(5) Roviaro G, Rebuffat C, Varoli F, et al. Videothoracoscopic excision of mediastinal masses: indications and technique. Ann Thorac Surg 1994; 58:1679-1683; discussion 1683-1674

(6) Roviaro G, Varoli F, Nucca O, et al. Videothoracoscopic approach to primary mediastinal pathology. Chest 2000; 117:1179-1183

(7) Roviaro GC, Rebuffat C, Varoli F, et al. Major thoracoscopic operations: pulmonary resection and mediastinal mass excision. Int Surg 1996; 81:354-358

(8) Tarrado X, Ribo JM, Sepulveda JA, et al. Thoracoscopic thymectomy. Cirugia Pediatrica 2004; 17:55-57

(9) Cheng YJ, Wu HH, Chou SH, et al. Video-assisted thoracoscopic management of mediastinal tumors. J Soc Laparoendosc Surg 2001; 5:241-244

(10) Mehran R, Ghosh R, Maziak D, et al. Surgical treatment of thymoma. Can J Surg 2002; 45:25-30

(11) Mack MJ, Scruggs G. Video-assisted thoracic surgery thymectomy for myasthenia gravis. Chest Surg Clin North Am 1998; 8:809-825, discussion 827-834

(12) Yim AP. Video-assisted thoracoscopic resection of anterior mediastinal masses. Int Surg 1996; 81:350-353

(13) Ellis K, Austin JH, Jaretzki A 3rd. Radiologic detection of thymoma in patients with myasthenia gravis. AJR Am J Roentgenol 1988; 151:873-881

(14) Singhal S, Shrager JB, Rosenthal DI, et al. Comparison of stages I-II thymoma treated by complete resection with or without adjuvant radiation. Ann Thorac Surg 2003; 76:1635-1641; discussion 1641-1632

(15) Mangi AA, Wright CD, Allan JS, et al. Adjuvant radiation therapy for stage II thymoma. Ann Thorac Surg 2002; 74:1033-1037

Yu-Jen Cheng, MD; Eing-Long Kao, MD; and Shah-Hwa Chou, MD

* From the Division of Thoracic Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.

Correspondence to: Yu-Jen Cheng, MD, Division of Thoracic Surgery, Department of Surgery, Kaohsiung Medical University Hospital, 100 Shih-Chuan First Rd, Kaohsiung 80708, Taiwan; e-mail:

COPYRIGHT 2005 American College of Chest Physicians
COPYRIGHT 2005 Gale Group

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