1. Staff Members of Cardio-thoracic Surgery Departments Egypt
Mediastinum
Staff Members of Cardio-thoracic Surgery Departments
Egypt

2. ANATOMY
Mediastinum is the space between the thoracic inlet and the diaphragm, the right and left pleural surfaces, the sternum and the vertebral column.
It is divided into superior and inferior mediastinum by an arbitrary line extending from the manubrio-sternal angle to T4/T5 intervertebral space. Anterior + Superior >>> Anterosuperior. Middle. Posterior.

3. Contents
Anterior or anterosuperior: Contains the thymus, lymph nodes and fat.
Middle : Contains the heart and pericardium , superior and inferior venae cavae , ascending aorta , aortic arch and its branches , brachiocephalic vein , pulmonary arteries and veins , phrenic and vagus nerves , trachea and main bronchi , lymph nodes and fat.
Posterior: Contains the esophagus, descending aorta, azygous and hemiazygous veins, thoracic duct, sympathetic chain and lymph nodes.

4. Mediastinal Masses and Cysts
Differential diagnosis of a mediastinal mass
Anterosuperior mediastinum (4Ts)
Thymic tumor or cyst.
Thyroid (Retrosternal thyroid or neoplasm).
Teratoma (Germ-cell tumors).
T Lymphoma.

5. 2. Middle mediastinum
Lymphadenopathy.
Vascular: Aortic aneurysm, anomalies of great vessels.
Pericardial cyst or diverticulum.
Bronchogenic cyst.
Tracheal tumors.
Parathyroid tumors or cysts.
Neural tumors of the phrenic, vagus, sympathetic nerves.
Morgagni hernia.

6. Congenital diaphragmatic hernia Morgagni’s hernia

7. 3. Posterior mediastinum
Neurogenic tumors ( benign B and malignant M ) are the most common posterior mediastinal tumors . ~ 70% are benign.
Peripheral intercostal nerves: B neurofibroma, neurilemmoma (Schwannoma from nerve sheath). M neurofibrosarcoma.
Sympathetic ganglia : B ganglioneuroma, neuroblastoma.
Paraganglia: phaeochromocytoma, paraganglioma B or M.
Meningocele.
Esophageal tumors, diverticulae, duplication cysts.
Hiatus hernia.
Thoracic duct cysts, cystic hygroma (lymphangioma).
Extramedullary hematopoesis.
Vertebral chordoma.
Paravertebral abscess (tuberculous, Pott’s).

8. Differential diagnosis of mediastinal Cysts
Anterior Mediastinum:
Dermoid cyst.
Thymic cyst.
Cystic degeneration in retrosternal Goitre.
Lymphatogenic cyst.
Midle Mediastinum:
Bronchogenic cyst.
Pericardial cyst.
Posterior Mediastinum:
Foregut cyst.
Cystic degeneration in neurogenic cyst.
Cystic hygroma.

9. The most common primary mediastinal masses are:
Neurogenic tumors %
Lymphoma %
Bronchogenic and Pericardial cysts %
Germ-cell tumors %
Thymoma %
Thyroid lesions %
Others (infections and other inflammatory conditions and metastatic lung cancer) 20%

10. Clinical Picture
Half of patients are asymptomatic with normal physical examination.
Symptomatic lesions and lesions in children are more likely to be malignant.
1. Symptoms
Local: Pain (chest or back), dyspnea, cough, dysphagia,…
Systemic: Fever, malaise, weight loss, night sweats,…
2. Signs
Local: Cervical lymphadenopathy, facial and arm swelling, tracheal deviation.
General: Testicular masses, hepatosplenomegaly, muscle weakness.

11. Investigations 1. Laboratory
CBC: Anemia, leucocytosis, thrombocytopenia.
Lactate dehydrogenase: Elevated in lymphomas, seminomas.
ß-human chorionic gonadotrophin (β-HCG ): Elevated in non-seminomatous germ-cell tumors. Increased in only 10% of seminomas.
α-fetoprotein : Elevated in non-seminomatous germ-cell tumors. It is normal in pure seminoma.
Alkaline phosphatase and calcium: For parathyroid tumors.
Urine metanephrines: Vanilyl mandelic acid (VMA) increased in phaeochromocytoma.

12. 2. Radiological
CXR .
CT scan with IV contrast.
MRI for neurogenic and vascular lesions.
Angiography for vascular lesions.
Esophagogram for posterior mediastinal masses.
Radionuclide scintigraphy for thyroid or parathyroid masses.
Gallium scan in lymphoma.

13. Mediastinal mass will not contain air bronchograms.
The margins with the lung will be obtuse, while lung mass abuts the mediastinal surface and creates acute angles with the lung,
Mediastinal lines will be disrupted.
Associated spinal, costal or sternal abnormalities.

14. On the left there is a lesion that has an acute border with the mediastinum. This must be a lung mass (pancoast tumor). On the right shows a lesion with an obtuse angle to the mediastinum. This must be a mediastinal mass. 

15. CT & MRI

16. 3. Biopsy Needle: Endoscopy: Surgery: Fine-needle aspiration biopsy.
Core-tissue biopsy.
Endoscopy:
Mediastinoscopy.
Video-assisted thoracoscopic surgery (VATS).
Bronchoscopy and trans-bronchial lung biopsy.
Esophagoscopy.
Surgery:
Anterior mediastinotomy.
Thoracotomy.

17. Video-Assisted Mediastinoscopy

18. Treatment
The treatment used for mediastinal tumors depends on the type of tumor and its location:
Thymic tumors require surgical resection, may followed by radiation or chemotherapy.
Lymphomas are recommended to be treated with chemotherapy followed by radiation.
Neurogenic tumors found in the posterior mediastinum are treated by surgical excision.

19. THYMOMA Definition: Tumor originating from thymic epithelial cells.
Clinical picture:
Most common tumor of the anterior mediastinum.
10% of patients with myasthenia gravis have thymoma.
40% of patients with thymoma have myasthenia gravis.
Patients may be asymptomatic, or
Symptomatic with the previously mentioned symptoms of mediastinal masses especially muscle fatigue characteristic of myasthenia gravis.

20. Specific investigations :
Acetylcholine receptor antibody levels & Electromyography for suspected myasthenia gravis.
CT Chest.
Biopsy: needle, core, mediastinoscopy or open via mediastinotomy. Preoperative biopsy is recommended if the tumor invades mediastinal structures, appears unresectable, or associated with pleural or pericardial effusion.

21. CT scan of thymoma

22. Pathological cell type classification:
Epithelial predominant (most aggressive).
Lymphocytic.
Mixed.
Spindle cell.
N.B: Myasthenia Gravis occurs mostly with lymphocytic variety.

23. Staging
Stage I:
No invasion of capsule microscopically or macroscopically.
Stage II:
Microscopic or macroscopic invasion of capsule or invasion into mediastinal fat or pleura.
Stage III:
Invasion of lung, great vessels, pericardium.
Stage IVa:
Pleural or pericardial metastases.
Stage IVb:
Distant metastases.

24. Treatment Stage I Total thymectomy.
Stage II Total thymectomy+ postoperative radiation.
Stage III Total thymectomy &resection of all non-vital structures invaded by the tumor + postoperative radiation & chemotherapy.
If the tumor appeared unresectable give chemotherapy and radiation is followed by surgical debulking.
Stage IVa Chemotherapy followed by resection + postoperative irradiation.
StageIVb Chemotherapy.

25. Thymoma

26. Thymic tumour with myasthenic manifestations

27. Definition: MYASTHENIA GRAVIS
MG is an autoimmune disease caused by anti-acetylcholine receptor (anti-AChR) antibodies, characterized by muscle weakness and rapid fatigue of the voluntary muscles including ocular ones.

28. Pathiphysiology
Acetylcholine normally transmits nerve impulses to muscle fibers at the neuromuscular junction, causing the muscles to contract. Patients with MG form antibodies against the acetycholine receptors. The thymus gland appears to be involved as it produces acetylcholine receptor antibodies that interfere with neuromuscular transmission.

29. A neuromuscular junction
1. Axon 2. Muscle cell membrane (sarcolemma) 3. Synaptic vesicle 4. Nicotinic acetylcholine receptor 5. Mitochondrion

30. Physical examination
Muscle fatigability can be tested for many muscles. A thorough investigation includes:
looking upward and sideward for 30 seconds: ptosis and diplopia.
looking at the feet while lying on the back for 60 seconds
keeping the arms stretched forward for 60 seconds
ten deep knee bends
walking 30 steps on both the toes and the heels
five situps, lying down and sitting up completely
"peek sign" - after complete initial apposition of the lid margins, they quickly (within 30 seconds) start to separate and the sclera starts to show.

31. Osserman Clinical Classification
Grade I: ocular type
Grade II: generalized type
Grade III: severely generalized
Grade IV: Myasthenic Crisis.

32. Diagnosis
Diagnosis of MG requires a characteristic history & physical findings, as well as two positive diagnostic tests:
Electromyography (EMG):considered to be the most sensitive test for MG.
Antibodies against the acetylcholine receptor. The test has a reasonable sensitivity of 80–96%, but in ocular myasthenia, the sensitivity falls to 50%.
Edrophonium test (Tensilon test) . Patient response to anticholinesterase. Tensilon is most common used as it is rapid onset (30 seconds) and short duration (3minutes).

33. Thymona with MG

34. Management
Anticholinesterase agents: (Neostigmine, pyridostigmine) strengthen neuromuscular transmission. They prolong the effect of acetylcholine that signals the muscles to act.
Steroids (prednisone/prednisolone): For more severe cases of MG to suppress the body's immune system. Other immunosuppressive drugs, such as, cyclosporin, mycophenolate, and azathioprine can be used.

35. Management Cont.
Plasmapheresis (Blood plasma exchange process): Removes from the blood antibodies and other substances that interfere with the transmission of nerve impulses. This is highly indicated in Myasthenic crisis.
Intravenous immunoglobulin therapy (IVIG): Injection of immunoglobulins. Patients receive between 3 and 12 infusions.
Thymectomy: Complete removal of the thymus through sternotomy approach (especially in thymomatous MG). Thymectomy is the optimal management for improvement in MG.

36. NEUROGENIC TUMORS Most common posterior mediastinal tumors.
Asymptomatic unless large, invasive, with extension through the intervertebral foramen into the spinal canal (dumbbell tumor).
10% are malignant
Malignant tumors occur more frequently in children.

37. Posterior Mediastinal Mass Benign neurogenic tumour

38. DUMBBELL TUMOUR

39. Treatment: Intrathoracic disease only: Thoracotomy.
I- Most of the tumors should be excised :
Intrathoracic disease only: Thoracotomy.
Dumbbell tumors: Laminectomy performed initially to prevent cord injury >>> Followed by thoracotomy.
Paragangliomas: Excision (may invade vascular structures e.g. aorta, heart).
Phaeochromocytoma: Preoperative α- and - receptors blockade + excision.
II- Neuroblastoma: Chemotherapy& radiation. Excision for residual masses.
Question? Mention 3 causes of surgically correctable hypertension? Phaeochromocytoma, Coarctation, Renal artery stenosis.

40. GERM-CELL TUMOR Germ cell tumor (GCT)
Is a neoplasm derived from germ cells.
Anterior mediastinum is the most common site of extragonadal GCT.
GCT can be cancerous or non-cancerous tumors. 50% of GCT are benign teratomas.
GCT 15% of primary mediastinal masses.
Males aged years are affected.
Examination should include testicular examination with ultrasound.
Tumour markers:
ß-human chorionic gonadotrophin (β-HCG ): Elevated in non-seminomatous germ-cell tumors. Increased in 10% of seminomas.
α-fetoprotein : Elevated in non-seminomatous germ-cell tumors. It is normal in pure seminoma.

41. Classification 1-Teratoma: Tumor markers are negative in pure forms.
Pathologically it contains all components of ectoderm (skin, hair and teeth), Endoderm (blood vessels) and Mesoderm (muscle).
Encapsulated tumors are excised.
Teratoma (B., M.)include mature teratoma, dermoid cyst, immature teratoma, teratoma with malignant transformation.
Teratocarcinoma refers to a germ cell tumor that is a mixture of teratoma with embryonal carcinoma, or with choriocarcinoma, or with both.

42. Anterior mediastinal mass - benign Dermoid Cyst

43. 2-Seminoma (synonyms germinoma, dysgerminoma): Malignant
2-Seminoma (synonyms germinoma, dysgerminoma): Malignant. Tumor marker (10% have elevated hCG). Seminomatous tumors tend to grow slower than nongerminomatous tumors, and have a higher 5 year survival rate. The survival rate for germinomatous tumors is higher in part because these tumors are very sensitive to radiation, and they also respond well to chemotherapy. The primary management involves combination chemotherapy (cisplatin, bleomycin, etoposide, and vinblastine) + large volume radiotherapy.

44. 3-Nonseminomatous:
Malignant
Include embryonal carcinoma, yolk sac tumour, choriocarcinoma and mixed tumor histology.
Compared to seminomatous tumors, nonseminomatous tumors tend to grow faster, have an earlier mean age at time of diagnosis, and have a lower 5 year survival rate.
The prognosis for nongerminomatous tumours has improved dramatically, however, due to the use of platinum-based chemotherapy regimens.
Tumor markers (β-HCG, α-fetoprotein) are elevated.
Tissue diagnosis is preferable but therapy may be initiated on the basis of elevated markers alone.
Management is primarily cisplatin-based chemotherapy.
Residual masses causing compressive symptoms require resection.

45. Lymphoma Lymphoma is a group of tumors that develop from lymphocytes.
There are two main types: Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL).
Multinucleated Reed–Sternberg cells (RS cells) are the characteristic histopathologic finding of Hodgkin's lymphoma.
 Mediastinal lymphoma is generally a part of widespread disease.

46. LYMPHOMA Cont. Imaging is done to determine spread.
Biopsy of lymph node (tissue core needle or surgical biopsy). Management depends on accurate tissue diagnosis.
Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy and surgery.
Chemotherapy is the mainstay of treatment, but radiotherapy or bone-marrow transplantation may be used.

47. Bilateral Hilar Lymphadenopathy (BHL)
Question? What are the causes of BHL seen radiologically?
Lymphoma, Sarcoidosis, TB.

48. BHL
CT scan of the chest showing lymphadenopathy in the mediastinum due to sarcoidosis.
Chest X-ray showing Bilateral hilar lymph node enlargement

49. BRONCHOGENIC CYST
Located close to the main stem bronchus, trachea or carina (presents with airway obstruction) or in the pulmonary parenchyma especially lower lobes (presents with recurrent infection).
Often communicates with the bronchial lumen.
Lined by ciliated columnar or cuboidal epithelium, may contain cartilage and mucous glands.
Indications for surgical excision:
Enlargement of the cyst.
Development of symptoms.

50. BRONCHOGENIC CYST

51. ENTERIC CYST Along the esophagus, may be embedded within its wall.
Lined by any type of alimentary tract epithelium.
May compress the esophagus or respiratory tree and may ulcerate.
CXR and CT show cystic lesion of low density.
Treatment is surgical excision.

52. PERICARDIAL CYST Located near the cardiophrenic angles.
75% are on the right side.
10% communicate with the pericardial sac.
Diagnosis is accurate by CT scan, echocardiography or needle aspiration if possible (clear springwater fluid).
Exision Thoracotomy or VATS is required to obtain tissue diagnosis or if the patient is symptomatic.  

53. PERICARDIAL CYST

54. RETROSTERNAL GOITRE
More than 50% of the thyroid is below the thoracic inlet.
Indications for excision are: Respiratory distress (sudden or chronic with tracheomalacia), dysphagia, SVC obstruction and hyperthyroidism.
Retrosternal goiter is removed using a collar incision with or without sternotomy.
True ectopic goiter (has a thoracic vascular supply), goiter with posterior mediastinal extension or malignant retrosternal goiter are removed using thoracotomy.

55. RETROSTERNAL GOITRE

56. Mediastinitis Etiology:
Median sternotomy wound infection (following open heart surgery and sternal dehiscence).
Esophageal perforation.
Local spread of infection (from lung, pleura, subphrenic, ribs, vertebrae, head and neck or penetrating injury).
Hematogenous and lymphatic spread (from distant septic sources).
Idiopathic.

57. Clinical Picture: Pain, dyspnea, fever with high WBC count.
Sternal dehiscence (fullness and erythema of the wound, local tenderness, discharge, palpable separation of the sternal edges on coughing).

58. Investigations : 1. Laboratory: Leucocytosis, … 2. CXR, CT chest:
Broad mediastinum.
Mediastinal abscess with fluid level.
Evidence of sternal dehiscence.
Associated pathology. 

59. Treatment: Systemic antibiotics. Surgical debridement .
Irrigation of the mediastinum with Povidone iodine solution and antibiotics.
Drainage of any mediastinal collection.
Deal with underlying pathology.
Reclosure of the sternum in sternal dehiscence.

60. SUPERIOR VENA CAVA SYNDROME
Etiology :
Malignant diseases: Cancer lung (75%), lymphoma (10%), mediastinal tumors as germ- cell tumors, malignant thymoma and metastases (5%).
Benign diseases: Fibrosing mediastinitis, retrosternal goitre and aneurysms of great vessels (5%).
Iatrogenic causes: Thrombosis secondary to transvenous pacemakers or central venous lines as CVP, portcath, Denver & leVeen shunts and renal dialysis catheters (5%).

61. Clinical Picture:
Symptoms: Dyspnea, cough, face and/or arm swelling, chest pain, syncope, headache, confusion.
Signs: Edema and prominent veins of the head, neck, upper trunk and arms, cyanosis and plethora, papilledema, Horner’s syndrome, vocal cord paresis.

62. Investigations : CXR: Mediastinal mass.
CT scan chest with IV contrast: Level of SVC obstruction, extent of mediastinal disease and venous collaterals.
MRI: Mediastinal vascular anatomy.
Venography: Simultaneous bilateral arm venogram · Defines site of SVC obstruction, · Identifies thrombus obstruction,
. Pattern of collateral vessels.
Serum markers -HCG or -fetoprotein: Germ-cell tumor.
Biopsy: Percutaneous needle biopsy, bronchoscopy, mediastinoscopy, mediastinotomy, VATS, thoracotomy.

63. Treatment :
Medical: Elevation of the head, oxygen, diuretics, salt restriction, steroids for laryngeal edema or brain metastases, anticoagulants for venous thrombosis.
Radiotherapy: For thoracic malignancy.
Chemotherapy: For lymphoma or small cell lung cancer. May be combined with radiotherapy.
Intravascular stents.
Surgery
Bypass using venous autografts or synthetic tube grafts for patients with benign disease and selected patients with malignancy.
Resection and vascular reconstruction: For localized tumors