Sternotomy and removal of the tumor

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2 Sternotomy and removal of the tumor

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6 All thymomas originate from epithelial thymic cells 4% of them consist of a pure population of epithelial cells Most have mixed populations of lymphoid cells to a varying extent

7 20% of all mediastinal neoplasms 50% of all primary tumors in the anterior compartment 90% of thymic tumors are thymomas

8 Slow-growing tumors Exhibit malignant potential: Local invasion Systemic metastasis without overt cytological features of malignancy More common between ages 40 to 60

9 ~50% - asymptomatic, discovered incidentally on CXR or at autopsy ~30% local symptoms related with pressure or local invasion: SVC sdr., cough, chest pain, dysphonia, dysphagia ~20%- 70% associated with an autoimmiune disease: Myasthenia gravis Pure red cell aplasia Polymyosistis hypogammaglobulnemia

10 Chest CT scan is the imaging procedure of choice Thymic enlargement should be determined because most enlarged thymus glands on CT scan represent a thymoma. CT scan with intravenous contrast dye is preferred to show the relationship between the thymoma and surrounding vascular structures, to define the degree of its vascularity, and to guide the surgeon in removal of a large tumor, possibly involving other mediastinal structures

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14 Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. Positron emission tomography (PET) scan. In a PET scan, radioactive sugar molecules are injected into the body. Cancer cells absorb sugar more quickly than normal cells, so they light up on the PET scan. PET scans are often used to complement information gathered from CT scan, MRI, and physical examination. CT scanning reveals evidence of an anterior mediastinal mass, the PET scan shows a hypermetabolic mass consistent with this location, thereby raising suspicion of malignancy. PET scanning should be added to the armamentarium as an available diagnostic modality to aid in staging and excluding extramediastinal involvement

15 Biopsy: If a patient presents with atypical features or is found to have an invasive tumor and is under consideration for induction therapy, obtaining preoperative biopsy is indicated. The limited anterior mediastinotomy (Chamberlain approach) is the standard approach that typically is performed over the projection of the tumor. A thoracoscopic approach for biopsy also can be used

16 No clear histologic distinction between benign and malignant thymomas exists. The propensity of a thymoma to be malignant is determined by the invasiveness of the thymoma.

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18 The preferred approach is a median sternotomy providing adequate exposure of the mediastinal structures and allowing complete removal of the thymus, If the tumor is small and appears readily accessible, perform a total thymectomy with contiguous removal of mediastinal fat. If the tumor is invasive, perform a total thymectomy in addition to en bloc removal of involved pericardium, pleura, lung, phrenic nerve, innominate vein, or superior vena cava. Resect one phrenic nerve; however, if both phrenics are involved, do not resect either nerve, and debulk the area. Clip areas of close margins or residual disease to assist the radiation oncologist in treatment planning

19 Their morphologic heterogeneity has caused much confusion regarding their classification. Several classifications have been proposed to correlate histology and clinical course. Previous studies have shown that the mediastinal invasion as reflected by the staging system of Masaoka negatively affects survival

20 Tumor extent but also grading the tumor could be required to predict prognosis and recurrence pattern which might help to define more precisely the role of adjuvant and neoadjuvant treatments. Therefore, not only staging, the several histologic classifications have been assessed, but they did not help to predict the evolution of thymic tumors after resection

21 WHO Histologic Description Free Survival at 10 years, % A Medullary thymoma 100 AB Mixed thymoma 100 B1 Predominantly cortical thymoma 83 B2 Cortical thymoma 83 B3 Well-differentiated thymic carcinoma 35 C Thymic carcinoma 28 Series of 100 thymomas resected in Japan between 1973 and 2001 using the WHO classification.

22 The prognosis of a person with a thymoma is based on the tumor's gross characteristics at operation, not the histological appearance. Benign tumors are noninvasive and encapsulated. Conversely, malignant tumors are defined by local invasion into the thymic capsule or surrounding tissue. The Masaoka staging system of thymomas is the most commonly accepted system. Preponderance of evidence indicates that all thymomas, except completely encapsulated stage 1 tumors, benefit from adjuvant radiation therapy

23 Relapse after primary therapy for a thymoma may occur after years. Therefore, long-term follow-up probably should continue to be performed throughout the patient's life.

24 Multivariate analysis showed age, gender, myasthenia gravis, and postoperative adjuvant therapy not to be significant predictors of survival after complete resection, whereas the Muller-Hermelink and Masaoka classifications were independent significant predictors for overall (p < 0.05)

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27 Uncommon and lethal cancer. Currently no standard treatment. Asbestos exposure is major risk factors.

28 Asbestos belongs to the family of silicate fiber. Include two mineralogical groups: Amphibole and Serpentine.

29 Narrow and straight fibers. Migrate through the lymphatics of pulmonary parenchyma and accumulate in interstitial space and subpleural region. Crocidolite asbestos(blue asbestos)-- The most associate with malignant mesothelioma.

30 Large, curly shaped fiber. do Not travel beyond the major airways. Chrysotile(white asbestos, the only member of Serpentin) -- More associate with lung cancer.

31 Nonspecific, Chest pain, dyspnea, pleural effusion, pericardial effusion, weight loss, cough, anorexia, weakness, fever, hemoptysis. Horner s syndrome. Spontaneous pneumothorax.

32 Abnormal ECG Sinus tachycardia (42%). Echocardiographic findings. No specific tumor marker. Rise serum hyaluronan. CA-125 (20%).

33 Chest-x ray Variable and related to stage of tumor. Large pleural effusion, pleural thickening, pleural-based mass. Encasement of lung and obliteration of pleural space. Involve pericardium and pericardial effusion. Chest wall invasion, invasion through diaphragm. CT Most accurate noninvasive way to stage. PET scan.

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37 Thoracentesis, cytology(positive rate 30-50%). Percutaneous pleural biopsy. Thoracoscopy. Open pleural biopsy. AVOID Exploratory thoracotomy. Bronchoscopy. Meidastinoscopy. Bone scans.

38 An accurate staging system is needed to guide the choice of therapy for patients with mesothelioma and ultimately to assess the results of treatment with different modalities Staging systems The most widely used staging system is the tumor (T), node (N), metastasis (M) staging system that has been adopted by both the International Union Against Cancer (UICC) and the American Joint Committee on Cancer

39 Clinical staging of malignant mesothelioma is performed radiographically in patients with potentially resectable malignant mesothelioma. Although radiographic staging evaluation is warranted, accurate staging is only possible at the time of operation

40 Patient with malignant mesothelioma face a dual problem Control of the locoregional tumor throughout the course of their disease, prevention of distant metastases as late manifestation of their cancer. Choice of treatment Location and extent of he tumor, the general medical condition of patient. Surgery, radiation, chemotherapy, immunotherapy, supportive care.

41 Still the mainstay of treatment. Three operation (1). Extrapleural pneumonectomy. (pleuropneumonectomy) (2). Pleurectomy-decortication. (3). Palliative limited pleurectomy.

42 En bloc resection of pleura, lung, ipsilateral hemidiaphragm, pericardium, Value Controversial. Operative mortality 6-30%. Preoperative CT, lung function, ventilationperfusion scan, cardiac function evaluate.

43 Remove all gross pleural disease, without removing underlying lung. Also remove hemidiaphragm and pericardium.

44 Resection parietal pleura to control pleural effusion. Thoracoscopy and talc poudrage High effective in controlling effusion.

45 The choice of a specific procedure EPP versus P/D is a function of the extent of disease within the thorax and the surgeon s judgement on the ability to achieve a MCR while preserving lung parenchyma. There are no randomized trials that compare EPP versus P/D.

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47 Patients with malignant pleural mesothelioma typically present with pulmonary symptoms. Chest imaging typically shows unilateral pleural thickening and pleural effusion. Paraneoplastic syndromes can be associated with pleural mesothelioma, but rarely are the initial manifestation of disease. The diagnosis of malignant mesothelioma requires a tissue sample. The differential diagnosis of malignant pleural mesothelioma includes inflammatory reactions, which can mimic pleural mesothelioma, as well as metastases from other malignancies. Thoracentesis and closed pleural biopsy are the initial procedures in most cases. If this is not diagnostic, surgical intervention is required to obtain an adequate tissue sample.

48 Clinical staging primarily relies upon imaging studies to assess the extent of disease and determine whether or not the patient is a candidate for surgical resection. However, clinical staging often underestimates the extent of disease, and intraoperative staging provides a more reliable assessment of whether or not the patient is a candidate for surgical resection.

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