Case Presentation HPI. PMHx: HTN, BPH, psychiatric disorder, negative cardiac stress test 4/2010. Allergies: NKDA

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2 Case Presentation HPI 62 year-old male presents with several episodes of anterior chest pain. Full cardiac evaluation was negative for ischemia. CT scan revealed a 4cm anterior mediastinal mass. Pt denies cough or respiratory issues. No weakness or diplopia. PMHx: HTN, BPH, psychiatric disorder, negative cardiac stress test 4/2010 Allergies: NKDA Meds: Lutensin, Atenolol, Norvasc, Fomax, Zyprexa, ASA 81 Shx: non-smoker

3 Case Presentation Physical Exam Afebrile, VSS Pupils equal and reactive, no ptosis No bruits, no lymphadenopathy S1S2, RRR Labs Hb/Hct: 13/39 Electrolytes- wnl Coags- wnl AChR-AB: negative Lungs clear bilaterally Soft abd NT/ND, no inguinal LN s

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5 CT scan

6 CT Scan

7 OR Procedure: Partial sternotomy, excision of thymic mass, partial pericardectomy, partial excision of innominate vein with patch reconstruction Pathology: Thymus- invasive squamous cell Ca of thymic origin Margins- all negative, except posterior (pericardial)- positive Positive lymphovascular invasion 2/9 LN positive for carcinoma T3, N1, Mx

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16 Post-Operative Course Stable overnight stay in PACU on POD#0 Clears and OOB on POD#1 Chest tube output around 300 ml SSF Chest tubes removed on POD# 3 Discharged Home on POD#5

17 Mediastinum Midline region between the two lungs and their pleural coverings Occupied principally by heart, great vessels, trachea, bronchi, esophagus, and thymus Divided into Superior and Inferior (anterior, middle, and posterior)

18 Mediastinum Most common tumors of anterior superior mediastinum 4-T s- thymoma, terrible lymphoma, teratoma and thyroid lesions These represent more than 90% of all anterior mediastinal masses Posterior mediastinum DATES: Descending aorta, Azygous vein and hemiazygos vein, Thoracic duct, Esophagus, Sympathetic trunk/ganglia Thymoma is the most common mediastinal neoplasm in adults

19 Thymus A lymphoepithelial organ derived embryologically from 3 rd pair pharyngeal pouches that descend caudally and medially on the 7 th week of life By the 8 th week the gland has fused to form a four-lobed gland attached to the anterior pericardium Can be as cephalad as the hyoid bone or as far caudad as xiphoid process

20 Thymus Fully developed, it is a bilobed gland that sits in the anterior mediastinum It is separated from sternum by loose connective tissue, it lies anterior to pericardium and great vessels It can extend laterally to phrenic nerves and is partially covered by the pleural reflections It is in close contact to the left inomminate vein

21 Thymus Arterial supply Internal thoracic (mammary)- main Inferior thyroid Pericardiophrenic arteries Venous drainage From both lobes, veins ascend posteriorly into left brachiocephalic or rarely directly into SVC

22 Thymus Central lymphoid organ that transforms null lymphocytes into thymic or T-lymphocytes, which are responsible for cellular immunity Symptoms may arise from direct lesion compression or invasion, as well as from immunologic, hyperplastic or neoplastic manifestations

23 Thymoma Thymomas are epithelial tumors of the thymus 65% of thymomas are encapsulated (noninvasive) and 35% are invasive. Most common mediastinal neoplasm in adults, 40% of all anterior mediastinal masses Most pts between ages at diagnosis Indolent growth pattern, but malignant due to its potential for local invasion, pleural dissemination and systemic metastases 1/3 of pts with localized dz are symptomatic: cough or chest pain

24 Thymoma Locally advanced or disseminated dz may present with severe CP, SOB, phrenic n. paralysis, pleural effusions, and/or SVC syndrome MG- most common autoimmune disorder associated with thymomas-ocurring in 30-40% of pts; 10% of MG pts have thymomas Up to 30% of pts with thymoma present with other immune disorders- red cell aplasia and hypogammglobulinema

25 Diagnosis CT scan with IV contrast Defines size and relationship to intrathoracic structures Presence of droplet metastases- parietal pleural deposits that are unique to thymomas Differ from malignant nonseminomatous germ cell tumors Alpha feto protein (AFP) and B-HCG Thyroid lesions are contiguous with thyroid gland on CT scan; I-131 nuclear scans to confirm

26 Droplet Metastases

27 Diagnosis Two main DDx for anterior mediastinal mass Lymphoma and thymoma Thymomas- older pts, association with immune disorder, no constitutional symptoms and no lymphadenopathy Utility of PET scan for thymomas is being evaluated cannot differ between lymphoma and thymoma, but it can identify droplet metastases

28 Diagnosis En bloc thymectomy for clinically determined early-stage thymoma For larger lesions FNA-lacks sensitivity CT guided core bx - seeding Anterior mediastinostomy Cervical mediastinoscopy VATS ( seeding)

29 Staging WHO classification based on histology Morphology and lymphocyte-to-epithelial ratio Masaoka Anatomic classification Most accepted system on which management recommendations are based

30 Staging Masaoka Anatomic classification Stage I: Macroscopically and microscopically encapsulated Stage II A- microscopic transcapsular invasion B- macroscopic invasion into surrounding fat or grossly adherent but not through pleura or pericardium Stage III: Invasion into neighboring organs A- without invasion into great vessels B- with invasion of great vessels Stage IV A- pleural or pericardial dissemination B- lymphogenous or hematogenous metastasis

31 Pre-op Assessment Anterior mediastinal mass (thymoma) H&P, AchR-AB assay, MuSKR-AB, EMG studies, TFTs, PFTs, CXR, CT scan, and MRI Pre-op optimization is crucial, especially when thymectomy is being done for MG Use pyridostigmine and immunosuppressive agents to optimize strength and respiratory status Plasmapheresis or IVIG may help in pts with VC < 2L 22% of pts with pre-op respiratory insufficiency will require long-term mechanical ventialation

32 Pre-op Assessment Major risk is weakness of oropharyngeal/respiratory muscles, leading to aspiration, inability to cough and respiratory failure Anticholinesterases (pyridostigmine) should be discontinued around 8hrs prior to surgery If stopped to early- myasthenic crisis If overmedicated- cholinergic crisis

33 Treatment Stage I/II: Complete en bloc thymectomy, and removal of all surrounding fat with avoidance of phrenic n. or intrapleural spread Median sternotomy provides excellent exposure and access VATS- being done, long term follow up is needed to compare with open approaches

34 Treatment Difficult to establish a stage III before surgery Unilateral phrenic n. resection can be done Potentially operable stage III dz Induction chemotx- cisplatin based with response rates of %, and resectability rates bet 35-70% Post op radiation after stage III resection for local control Stage IVa: induction chemotx, assess resectability; if not resectable- chemoradiation; steroids and octreotride as 2 nd line

35 Thymoma Prognosis at 5 and 10 yrs Stage I : 95%, 85% Stage II: 80%, 75% Stage III: 40-60%, 20-30% Stage IV a: 0-40%

36 Thymic Carcinoma This tumor is a rare variant of thymic lesions and is histologically and biologically different from invasive or malignant thymoma; these are malignant at microscopic level Incidence: <1% of thymic malignancies, 5 year survival is 30-50% Thymic carcinomas tend to be very invasive and difficult to resect completely Even in the setting of complete resection, recurrence is common both locally and at distant sites Typically, these are young men (< age 50 years) with an otherwise excellent performance status

37 Thymic Carcinoma PET scan better due to higher proliferative potential in thymic carcinoma. Aggressive combined-modality approach (induction chemotherapy, resection, and postoperative chemoradiotherapy) should be employed While a good response to induction therapy and complete resection will provide a significant disease-free interval, long-term survival is still unlikely

38 Conclusion Goal of thymectomy should be complete removal of all thymic tissue MC indications: thymic neoplasm or MG Thymoma should be resected because of its risk for invasive spread or morbidity due to mass effects Even advanced tumors with local invasion of resectable structures such as the pericardium, superior vena cava, or innominate vessels should be considered for resection with reconstruction

39 Surgery is the cornerstone for thymic malignancies Complete resection is the most constant and significant prognostic factor for progression-free and overall survival Radiotherapy Although thymomas are regarded as being moderately radiosensitive, controversy exists about its role as adjuvant therapy Chemotherapy

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41 Recommendations Stage I: Surgery to obtain microscopically complete resection Stage II-III (resectable): Surgery, post op RT controversial, but clearly recommended for incompletely resected tumors Increased Mediastinal recurrence-free survival from 0-79% vs 47% without adjuvant RT, No increase in overall survival

42 Recommendations Stage III-IV a (marginally resectable): Surgery and post-op radiation therapy, perioperative chemotherapy in incomplete resection (Level 2C evidence) Debulking surgery in debate, survival rates only 5-10% Stage III-IV a (initially unresectable) Upfront chemotherapy followed by surgery or radiation therapy depending on whether sufficient down-staging has been achieved. Stage IVB Chemotherapy is treatment of choice typically multiple agents.

43 Recommendations Local and Locoregional recurrences of thymoma Late recurrences 5-10 year are not uncommon In cases of recurrent thymoma, surgery remains the mainstay in therapy In nonresectable local recurrences, exclusive radiotherapy has been reported as an efficient treatment.

44 Key Points Tumors of the thymus represent a wide spectrum of diseases; Thymoma predominates Surgeon s role- knowledge of differential diagnoses, associated symptoms, palpable lymphadenopathy Pre-op management Surgery is the mainstay of therapy and obtaining complete resection is the most important prognostic factor Due to its rarity, further studies are warranted to evaluate and improve current therepeutic standards.

45 References Alavi A, Gupta N, Alberini JLPositron emission tomography imaging in nonmalignant thoracic disorders. Sem Nucl Med 2002; 22:293.and others Kelemen 3rd JJ, Naunheim KS: Minimally invasive approaches to mediastinal neoplasms. Sem Thorac Cardiovasc Surg 2000; 12:301. Kim ES, Putnam JB, Komaki R: Phase II study of a multidisciplinary approach with induction chemotherapy, followed by surgical resection, radiation therapy, and consolidation chemotherapy for unresectable malignant thymomas. Lung Cancer 2004; 44:369.and others Wright CD, Kessler KA: Surgical treatment of thymic tumors. Sem Thorac Cardiovasc Surg 2005; 17:20.

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