Ann Thorac Surg 2006;82:2266-2268
© 2006 The Society of Thoracic Surgeons
Case Reports
Thymic Small Cell Carcinoma Associated With Pulmonary Squamous Cell Carcinoma
Takashi Iwata, MDa,*,
Kiyotoshi Inoue, MDa,
Shinjiro Mizuguchi, MDa,
Ryuhei Morita, MDa,
Takuma Tsukioka, MDa,
Shigefumi Suehiro, MDb
a Department of Thoracic Surgery, Osaka City University Hospital, Osaka, Japan
b Department of Cardiovascular Surgery, Osaka City University Hospital, Osaka, Japan
Accepted for publication May 3, 2006.
* Address correspondence to Dr Iwata, Department of Thoracic Surgery, Osaka City University Hospital, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan. (Email: taiwata{at}med.osaka-cu.ac.jp).
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Abstract
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A 63-year-old man presented with dyspnea on effort. Chest computed tomography showed an anterior mediastinal mass and a lung mass in the right lower lobe. Thallium scintigraphy revealed accumulation in the mediastinal mass. Therefore, under diagnosis of invasive thymoma or thymic carcinoma associated with suspected lung cancer, exploratory right thoracotomy was undertaken through a median sternotomy with video-assisted thoracoscopic support. The lung mass was intraoperatively diagnosed as squamous cell carcinoma. Right lower lobectomy and total thymectomy were then carried out without additional incision. Thymic small cell carcinoma was diagnosed; therefore the patient received 50 Gy of irradiation to the mediastinum. Ten months after surgery the patient is alive without recurrence.
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Introduction
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To develop strategy of surgical treatment is sometimes problematic in patients with thymic tumor associated with lung cancer. The unusual association of a thymic neoplasm (ie, a small cell carcinoma) with other thoracic neoplasms, although rare, has been reported. We report a patient with an encapsulated tumor in the thymus that was composed of small cell carcinoma synchronously associated with squamous cell carcinoma in the lung; both were successfully resected in a single operation through a median sternotomy with video-assisted thoracoscopic support.
A 63-year-old man who was diabetic for 2 years presented with dyspnea on effort at a local clinic in March 2005. The patient was transferred to our hospital’s outpatient clinic for further evaluation and treatment on May 2. He did not complain of muscle weakness and had no neuroendocrine symptoms. Chest roentgenogram revealed right mediastinal bulging and a chest computed tomographic scan showed an anterior mediastinal mass of approximately 5 cm diameter, just anterior to the trunk of the right pulmonary artery (Fig 1A). The outer rim of the mass was enhanced by contrast media in the late phase. In addition, another mass lesion was detected in the right lower lobe of the lung. The lung mass was approximately 1 cm in diameter and showed pleural indentation (Fig 1B). Thallium scintigraphy revealed accumulation of the isotope in the mediastinal mass. Invasive thymoma or thymic carcinoma was suspected. Diagnosis of the lung mass was needed to determine the best treatment option; however it was too small to take samples by either bronchoscopic or percutaneous needle biopsy. Every tumor marker was normal. We then diagnosed this patient with thymoma or thymic carcinoma associated with suspected lung cancer. Therefore, exploratory right thoracotomy was undertaken through a median sternotomy with video-assisted thoracoscopic support on June 1. An elastic hard mass (5 cm in size) was found in the anterior mediastinum and was easily removed from the left pulmonary artery trunk and surrounding tissue. Extended thymectomy seemed possible. The 1 cm diameter lung mass was detected in the right lower lobe, resected, and the specimen was sent for intraoperative frozen sectioning. Pathology showed the resected lung mass to be squamous cell carcinoma. Right lower lobectomy of the lung and dissection of mediastinal lymph nodes were then carried out. Video-assisted thoracoscopic maneuvers were useful in this procedure, and an extended thymectomy was performed next. Pathology postoperatively confirmed the lung cancer as poorly differentiated squamous cell carcinoma without mediastinal lymph node metastasis or pleural invasion and was diagnosed as T1N0M0 stage IA according to the International Union Against Cancer staging system. The mediastinal mass was diagnosed as thymic small cell carcinoma, having a higher nucleocytoplasmic ratio than the lung cancer, and with a necrotic part seen in the specimen. The tumor was encapsulated and capsular invasion was demonstrated (stage II according to the Masaoka staging system). Because of the histologic results, the patient received 50 Gy of irradiation therapy at the dissected area in the anterior mediastinum postoperatively. Chemotherapy was not added because the patient did not wish to receive it. Ten months after surgery the patient is surviving without recurrence.
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Fig 1. (A) Chest computed tomographic (CT) scan at the level of the ascending aorta, demonstrating a solid mass in the anterior mediastinum (arrow), in which the outer rim is enhanced by contrast media. (B) The CT scan at the level of the ninth thoracic vertebra shows a lung mass with pleural indentation (arrow).
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Comment
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Preoperative diagnosis of thymic malignancy is sometimes difficult. Thallium scintigraphy is useful to distinguish thymomas from thymic benign lesions [1] and is also useful to evaluate tumor viability of thymic carcinoma [2, 3]. The authors usually evaluate thymic tumors with thallium scintigraphy and single photon emission computed tomography to rule out malignant thymic tumors (ie, thymomas and thymic carcinomas) from benign thymic lesions. If positive accumulation is indicated by thallium scintigraphy and single photon emission computed tomography, we perform total thymectomy to avoid further multicentric occurrence of thymomas in the residual thymus. If not, benign lesion is highly suspected, and we will choose partial resection of the thymus through a video-assisted thoracoscopic procedure. We merely perform preoperative percutaneous needle biopsy to avoid tumor dissemination.
Small cell carcinoma in the mediastinum is sometimes problematic in diagnosis when associated with lung tumor. Because its origin is sometimes not distinguishable, a tumor may be just an enlarged metastatic lymph node in the mediastinum due to an undiagnosed pulmonary small cell carcinoma or lung cancer extending severely into the anterior mediastinum. Furthermore, small cell carcinoma that arises from the thymus is morphologically indistinguishable from a pulmonary small cell carcinoma. Treatment option is sometimes difficult to be arranged without exact clinical profile of each disease. In our case, the tumor in the thymus was well encapsulated and exact in the thymus. Therefore the anterior mediastinal tumor was easily defined as from an intraoperative thymic origin. Thus we could determine to treat thymic tumor and lung cancer separately but simultaneously by thymectomy and lobectomy.
In cases where both thymectomy and lobectomy are needed, an operative method would present another problem. Shimada and colleagues [4] reported a similar case. In that case, in which total thymectomy followed, left lower lobectomy was attempted through a median sternotomy; however, left intercostal thoracotomy was needed for a better view and an operative field. Through a median sternotomy, dissection of the posterior mediastinum can be difficult. In our case, we used a video-assisted thoracoscopic method to accomplish right lower lobectomy through a median sternotomy without making an extra-skin incision.
The operative method should be determined concerning prognosis of the both tumors. In our case, the lung cancer was peripheral squamous cell carcinoma, and good prognosis is predictable by lobectomy. Thymic small cell carcinoma is equivalent to poorly differentiated neuroendocrine carcinoma and grows rapidly as small cell carcinoma in lungs [5]. Even thymic carcinoma has a poor prognosis [6], the tumor was completely encapsulated and favorable prognosis was predicted by surgical resection. Thus preoperative and intraoperative evaluations are important. Video-assisted thoracoscopic method is useful to reduce invasiveness in such extended operation, and makes intraoperative evaluations easy and open to surgical option.
The optimal treatment of thymic carcinoma remains controversial. Both chemotherapy and radiotherapy are recommendable after resection of thymic carcinoma. However, Ogawa and colleagues [6] reported postoperative radiotherapy with or without chemotherapy is curative. In our case, the patient did not wish chemotherapy and was thus treated with irradiation alone.
In such cases, logical and balanced operative methods along with postoperative treatment need careful planning. Thoracoscopic resection of a thymoma is still an experimental alternative [7, 8]; however recent advances in both methodology and equipment seem helpful for planning a surgical strategy in these complicated cases.
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Acknowledgments
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We thank Hiroko Tanaka for her help in the preparation of the manuscript. The funding for this report was supported by Osaka City University Medical School, Osaka, Japan.
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References
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Abstract
Introduction
