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Thymoma Is it really a rare disease?


The thymus is a butterfly shaped organ located in the mediastinum of the thoracic cavity anterior and superior to the heart and posterior to the sternum. It is closely associated with the immune system and the endocrine system. The thymus serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. After puberty, the thymus starts to slowly shrink and become replaced by fat.


Thymoma is the most common neoplasm of the anterior mediastinum. Its peak incidence occurs in the fourth and fifth decades of life. No sexual predilection exists. Of patients with a thymoma, one third are asymptomatic. Thymoma is often detected incidentally. Sometimes it is discovered through a chest x-ray or chest CT-scan. One third of cases also have myasthenia gravis (MG). Patients with MG usually present with drooping of eyelids in the afternoon and weakness in arms and legs. In severe cases, the muscles that control breathing become too weak to do their jobs. Emergency treatment is needed to provide mechanical assistance with breathing. In addition, one third of thymoma cases present with local symptoms related to the tumor's encroachment on surrounding structures. These patients may present with cough, chest pain, superior vena cava (SVC) syndrome, dysphagia, and hoarseness.

เนื้องอกต่อมไทมัส (THYMOMA)

The Masaoka system is the most commonly accepted staging system for thymomas.

  1. Macroscopically and microscopically completely encapsulated
  2. The cancer has spread into the outer layer of the thymus
    a. Microscopic transcapsular invasion
    b. Macroscopic invasion into surrounding fatty tissue or grossly adherent to but not through mediastinal pleura or pericardium
  3. Macroscopic invasion into neighboring organs e.g. pericardium, great vessels, or lungs
  4. Metastasis
    a. Pleural or pericardial dissemination
    b. Lymphogenous or hematogenour metastasis

In most cases of thymoma, initial management is surgical.

  • Stage 1: surgical excision
  • Stage 2, 3: surgical excision and post-operative radiotherapy
  • Stage 4: surgical debulking, radiotherapy, and chemotherapy

VATS Thymectomy

 Video Assisted Thoracic Surgery (VATS) Thymectomy 
Conventionally, a total thymectomy is performed by splitting the sternum. With technological advancement, video-assisted thoracic surgery (VATS) is a minimally invasive surgical technique that can be performed instead of median sternotomy. During a video-assisted thoracic surgery procedure, a tiny camera (thoracoscope) and surgical instruments are inserted into your chest through small incisions in your chest wall. The thoracoscope transmits images of the inside of your chest onto a video monitor, guiding the surgeon in performing the procedure.

With this advanced technique, the patient will have less post-operative pain, smaller incision, and shorter recovery time. The hospital stay is only 1-3 days compared to 5-7 days for patients who undergo open surgery.

There are many clinical studies comparing this new surgical technique with open surgery in patients with stage 1-2 thymoma that has less than 4-5 centimeter tumor. The result shows that this new technique is feasible and comparable to sternotomy for the treatment of patients with thymoma with regard to morbidity, incomplete resection rate, and prognosis.

“Currently, thymectomy can be done by video-assisted thoracic surgery (VATS) which is a minimally invasive surgical technique. The outcome is comparable to the open surgery with less pain, shorter hospital stay and recovery time” said Dr. Padungkiat.

นพ.ผดุงเกียรติ ตั้งพิรุฬห์ธรรม

References: Dr. Padungkiat Tangpiroontham, a cardiothoracic surgeon specialized in minimally invasive thoracic surgery, Bangkok heart hospital and Wattanosoth hospital

2. Gu Z et al, Video-assisted thoracoscopic surgery versus open surgery for Stage I thymic epithelial tumours: a propensity score-matched study. Eur J Cardiothorac Surg. 2018 Jul 16.
3. Qian L et al, A comparison of three approaches for the treatment of early-stage thymomas: robot-assisted thoracic surgery, video-assisted thoracic surgery, and median sternotomy. J Thorac Dis. 2017 Jul;9(7):1997-2005. doi: 10.21037/jtd.2017.06.09.
4. Agatsuma H et al. Video-Assisted Thoracic Surgery Thymectomy Versus Sternotomy Thymectomy in Patients With Thymoma. Ann Thorac Surg. 2017 Sep;104(3):1047-1053
5. Siwachat S et al. Asian J Surg. 2018 Jan;41(1):77-85Comparative clinical outcomes after thymectomy for myasthenia gravis: Thoracoscopic versus trans-sternal approach.
6. Maniscalco P et al. Thorac Cardiovasc Surg. 2015 Apr;63(3):201-5Long-term outcome for early stage thymoma: comparison between thoracoscopic and open approaches.