Interact CardioVasc Thorac Surg 2008;7:1196-1198. doi:10.1510/icvts.2008.177162
© 2008 European Association of Cardio-Thoracic Surgery
Case report - Thoracic general |
Huge thymoma: role of preoperative WHO histological classification
Shin-ichi Takedaa,*,
Masaru Komaa and
Hajime Maedab
a Department of General Thoracic Surgery, Osaka General Medical Center, 3-1-56 Bandaihigashi, Sumiyoshi-Ku, Osaka, 558-8558, Japan
b Department of General Thoracic Surgery, Toneyama National Hospital, Toneyama 5-1-1 Toyonaka City, Osaka, 560-8552, Japan
Received 7 February 2008;
received in revised form 17 June 2008;
accepted 21 July 2008
Corresponding author. Tel.: +81-6-6692-1201; fax: +81-6-6606-7032.
E-mail address: stakeda{at}gh.pref.osaka.jp (S.-i. Takeda).
 |
Abstract
|
|---|
A 57-year-old woman was admitted to our hospital with complaints of recent onset of dyspnea on exertion. A chest computed tomography revealed a large mediastinal mass which extrinsically compressed the heart and mediastinal structures, occupying one half of the hemithorax. A needle biopsy was performed to find a thymoma with type AB according to the WHO classification. Based on the radiological and histological finding a surgery for the tumor was achieved by exploratory VATS thoracotomy followed by thymectomy through a median sternotomy with tumor extirpation of 910 g in weight. A definite diagnosis of thymoma (Masaoka I) without capsular invasion was obtained from the pathologic findings, including positive immunohistochemical staining for CD1a and cytokeratin.
Key Words: Huge thymoma; WHO classification; Masaoka stage
|
1. Introduction
|
|---|
Although thymomas are known to be the most common mediastinal tumors and to be located in the anterior mediastinum, Masaoka et al. [1] have proposed a staging system that was based on the extent of invasion into the mediastinal structures in thymomas. Surgery is a mainstay in the treatment for thymomas [2], even when they involve the adjacent organs, however, large tumor size (>15 cm) indicated higher death or recurrence rate in thymomas [3, 4], which indicated the necessity of neoadjuvant therapy that is performed for a locally advanced thymic carcinoma [5, 6]. On the other hand, a recently established WHO classification has shown that histologic classification subtype reflects oncologic behavior [7].
We herein report a case with a huge thymoma presenting with respiratory distress, that was primary resected based on the preoperative radiological and histological finding, and resulted in not performing unnecessarily neoadjuvant chemoradiotherapy.
|
2. Case report
|
|---|
A 57-year-old woman was admitted to our hospital with complaints of a recent onset of dyspnea on exertion. Her past and family history was not contributory. On physical examination, the patient appeared to be a well-nourished woman, without neurogenic symptoms of myasthenia gravis. A chest X-ray revealed a large mass occupying one half of the hemithorax (Fig. 1a). A chest computed tomography (CT) scan revealed a solid mass, 17 cm in size occupying the pleural space, which compressed and shifted the mediastinal structures (Fig. 1b). A bronchofiberscopy also revealed extrinsic stenosis of the left main and lower lobe bronchus due to the tumor. The laboratory data revealed no significant findings, including normal levels of serum tumor markers and anti-acetylcholine receptor antibody titer. Pulmonary function tests showed restrictive and obstructive impairment of %FVC of 47.1% and FEV1.0/FVC of 52.8%.
View larger version (90K):
[in this window]
[in a new window]
|
Fig. 1. A chest X-ray revealed a large mass occupying one half of the hemithorax (a). A chest computed tomography (CT) revealed a solid mass with a relatively sharp margin of 17 cm in size occupying the pleural space (b).
|
|
To establish the therapeutic strategy, a needle biopsy was performed, which revealed a mixture of a lymphocyte-poor type A and a more lymphocyte-rich type B component (Fig. 2a), namely type AB thymoma according to the WHO classification. Based on the radiological and histological finding, a primary surgery was scheduled. First, an exploratory video-assisted thoracic surgery (VATS) thoracotomy was performed which found no invasion of the tumor beyond parietal pleura, and then the huge thymoma was successfully resected with thymic tissue through a median sternotomy. Intraoperative bleeding was only 100 ml and the total operating time was 115 min which were less than we expected. Macroscopically, the resected tumor was an encapsulated elastic mass 17x13x13 cm in size, and 910 g in weight. The cut surface of the tumor revealed a yellow and white color without capsulation invasion (Fig. 2b), stage of I according to the Masaoka classification. Histologically, the tumor was diagnosed as type AB thymoma, and additional findings of immuno-histochemical staining for cytokeratin and CD1a confirmed the thymoma. The patient showed a fair recovery without any postoperative complication.
View larger version (99K):
[in this window]
[in a new window]
|
Fig. 2. A needle biopsy specimen revealed a mixture of a lymphocyte-poor type A and a more lymphocyte-rich type B component (a), namely type AB thymoma according to the WHO classification (a). Gross finding of the tumor: an encapsulated elastic mass 17x13x13 cm in size (b).
|
|
|
3. Discussion
|
|---|
Thymoma is the most common primary neoplasm in the anterior mediastinum with non-invasive and invasive character. As to the therapeutic strategy, a primary surgery is a mainstay of treatment for thymoma [2] when complete resection can be achieved. Poor prognostic factors included presence of tumor-related symptoms, large tumor size, and local invasion or metastasis in initial operation [3, 4]. However, large tumor size (>15 cm) is regarded as higher death or recurrence rate of 48.2% [4] in the early series. Thus, neoadjuvant therapy to aim at complete resection has been performed recently, which was applied for a locally advanced thymic carcinoma [5, 6]. As for the radiological diagnosis, obliteration of the fatty plane may aid to diagnose the invasion, however, Tomiyama et al. [7] showed that this finding was not helpful in distinguishing between a non-invasive and invasive thymoma. Thus, more information regarding biological behavior in the case of a borderline resectable case is required in terms of tumor size and local invasion.
By analysis of the recent reports by Okumura and colleagues [8, 9], WHO histological classification reflected the oncological behavior in terms of local invasion, which can-not be judged by radiological finding. A collective study by Kondo et al. [10] disclosed that type A and AB thymomas can be treated as benign tumors regardless of the tumor size, thus we attempted a primary resection without neoadjuvant therapy following VATS observation of the thoracic cavity to exclude the invasion beyond the extrapleural extension or dissemination.
Our experience has confirmed the importance of WHO histological classification, in particular before surgery, for a large tumor to determine the therapeutic yield.
|
References
|
|---|
- Masaoka A, Monden Y, Nakahara K, Tanioka T. Follow-up study of thymomas with special reference to their clinical stages. Cancer 1981;48:2485–2492.[CrossRef][Medline]
- Okumura M, Miyoshi M, Takeuchi Y, Yoon HE, Minami M, Takeda S, Fujii Y, Nakahara K, Matsuda H. Results of surgical treatment of thymomas with special reference to the involved organs. J Thorac Cardiovasc Surg 1999;117:605–613.[Abstract/Free Full Text]
- Blumberg D, Burt ME, Bains MS, Downey RJ, Martini N, Rusch V, Ginsberg RJ. Thymic carcinoma: current staging does not predict prognosis. J Thorac Cardiovasc Surg 1998;115:303–309.[Abstract/Free Full Text]
- Lewis JE, Wick MR, Scheithauer BW, Bernatz PE, Taylor WF. Thymoma. A clinicopathologic review. Cancer 1987;60:2727–2743.[CrossRef][Medline]
- Takeda S, Sawabata N, Inoue M, Koma M, Maeda H, Hirano H. Thymic carcinoma: clinical institutional experience with 15 patients. Eur J Cardiothorac Surg 2004;26:401–406.[Abstract/Free Full Text]
- Loehrer PJ, Jiroutek M, Aisner S, Aisner J, Green M, Thomas CR Jr, Livingston R, Johnson DH. Combined etoposide , ifosfamide, and cisplatin in the treatment of patients with advanced thymoma and thymic carcinoma. An intergroup trial. Cancer 2001;91:2010–2015.[CrossRef][Medline]
- Tomiyama N, Muller NL, Ellis S, Cleverley JR, Okumura M, Miyoshi S, Kusumoto M, Johkoh T, Yoshida S, Mihara N, Honda O, Kozuka T, Hamada S, Nakamura H. Invasive and noninvasive thymoma: distinctive CT features. J Comput Assist Tomo 2001;25:388–393.[CrossRef]
- Okumura M, Miyoshi S, Fujii Y, Takeuchi Y, Shiono H, Inoue M, Fukuhara K, Kadota Y, Tateyama H, Eimoto T, Matsuda H. Clinical and functional significance of WHO classification on human thymic epithelium neoplasms. A study of 146 consecutive patients. Am J Surg Pathol 2001;20:1469–1480.
- Okumura M, Miyoshi S, Fujii Y, Takeuchi Y, Shiono H, Inoue M, Fukuhara K, Kadota Y, Tateyama H, Eimoto T, Matsuda H. The World Health Organization histologic classification system reflects the oncologic behavior of thymoma: a clinical study of 273 patients. Cancer 2002;94:624–632.[CrossRef][Medline]
- Kondo K, Yoshizawa K, Tsuyuguchi M, Kimura S, Sumimoto M, Morita J, Miyoshi T, Sakiyama S, Mukai K, Monden Y. WHO histologic classification is a prognostic indicator in thymoma. Ann Thorac Surg 2004;77:1183–1188.[Abstract/Free Full Text]
|
|
Top
Abstract
1. Introduction