2. Anatomy
▪ The region of the body located between the two pleural spaces
▪ It is derived from the Latin words medius (middle) and stare (to stand)
and means literally "standing in the middle.“
▪ The mediastinum is a complex and tightly knit package of structures
immediately vital to the life of the individua-the central airways, the
heart, and the great vessels.
▪ Also contained within the mediastinum are glands, and organs,
including the esophagus, thymus, thoracic duct, vagus and phrenic
nerves, and lymphatics.
3. Cont’d
▪ The mediastinum extends from the diaphragm to the thoracic inlet
and is divided by anatomists into four regions that are defined by
their relationship to the pericardium:
– superior,
– anterior,
– middle,
– posterior.
▪ Thoracic surgeons generally divide the mediastinum into just three
compartments:
– anterior,
– middle,
– posterior
4. Cont’d
▪ The mediastinum contains a compact arrangement of vital
structures and other tissues abnormalities such as
infection, trauma, and neoplasm can have a profound
impact and can present with dramatic symptoms
▪ Because the mediastinum is relatively inaccessible to
physical examination, imaging studies such as computed
tomography (CT) play a particularly important role in the
evaluation of suspected pathology.
5.
6. Mediastinal Lesion
▪ The wide variety and diverse origins of tissues normally found within
the mediastinum account for the extraordinary assortment of tumors
and cysts that arise from them primary mediastinal lesions
▪ Secondary lesions of the mediastinum are derived from
extramediastinal tissues, such as thyroid, bone, or lung, and either
migrate into or metastasize to the mediastinum.
▪ Many benign lesions are asymptomatic and are discovered
incidentally, whereas malignant lesions are more likely to produce
symptoms from compression and invasion of adjacent structures.
12. Clinical Presentation
▪ Mediastinal lesions are symptomatic in 50%-75% of patients
▪ Symptoms can be caused by local mass effects, systemic effects of
tumorderived hormones and peptides, or infection.
▪ Local effects are dependent on the size and location of the lesion and
result from compression of adjacent structures
– Examples: cough, stridor, dyspnea, chest pain, and dysphagia
▪ Symptoms are also more common with malignant tumors are more
likely to fix, encase, and invade adjacent structures.
– Examples: Superior vena cava syndrome, back pain, and neurological deficits
such as Homer's syndrome or phrenic nerve palsy
13.
14. Diagnostic Evaluation
▪ RADIOLOGY
– Plain chest x-ray taken in two planes, posteroanterior and left lateral basic
information about the location of the mass within the mediastinum
– Diaphragm fluoroscopy, or sniff test to evaluate paradoxical motion of the
diaphragm on rapid inspiration indicative of phrenic nerve paralysis
– CT of the chest has replaced plain chest radiography as the diagnostic procedure
of choice for mediastinal masses
– MRI may enhance the diagnostic abilities of chest CT
– Echocardiography and FDG-PET have been commonly used High FDG
invasion in thymic carcinomas and invasive thymomas
15. Cont’d
▪ Histologic
– FNA or needle biopsy with CT guidance of a mediastinal mass may
provide sufficient tissue for diagnosis of thymic carcinoma or other
defined neoplasms
– Core needle biopsy, mediastinoscopy, or intrathoracic biopsy may
be considered for lymphomas in particular, and thymomas and
neural tumors
– Electron microscopy may be required for confirmation of specific
histologies
16. Thymoma
▪ The most common neoplasm of the anterosuperior compartment
▪ Peak incidence is in the third through fifth decades
▪ Radiograph: small, well-circumscribed mass or as a bulky lobulated
mass confluent with adjacent mediastinal structures
▪ Symptoms:
– chest pain,
– dyspnea,
– hemoptysis,
– cough,
– superior vena cava syndrome
– systemic syndromes caused by immunologic mechanisms
17.
18. A, CT Chest in a patient with myasthenia gravis and thymoma.The thymoma is small with a
plane of separation between the tumor and the pericardium.
B, CT Chest in a patient with a larger mediastinal mass.The location, character, and size are
noted.Transthoracic core needle biopsy was performed. Germ cell tumor markers were
normal. Pathology demonstrated thymoma. Subsequently, a 6.5 cm thymoma was
resected.There was no invasion of the pericardium. A complete resection (R0) was
accomplished.
19. Cont’d
▪ Systemic syndromes accompanies thymoma:
– Myasthenia Gravis most common
– pure red blood cell aplasia,
– pure white blood cell aplasia,
– aplastic anemia,
– Cushing’s syndrome,
– hypogammaglobulinemia,
– hypergammaglobulinemia,
– dermatomyositis,
– systemic lupus erythematosus,
– progressive systemic sclerosis,
– hypercoagulopathy with thrombosis,
– rheumatoid arthritis,
– megaesophagus,
– granulomatous myocarditis
22. Treatmentof Thymoma
▪ Surgery
– Complete surgical resection
– Median sternotomy with a vertical or submammary incision is most commonly
used
– bilateral anterolateral thoracotomies with transverse sternotomy, or “clam-shell
procedure”, preferred with advanced or laterally displaced large tumors
– Patients with MG and thymoma have a 56% to 78% 10-year survival rate and a
3% recurrence rate with 4.8% (1.7% since 1980) operative mortality after
extended thymectomy
▪ Radiation
– In stage II and III invasive disease, adjuvant radiation can decrease recurrence
rates after complete surgical resection from 28% to 5%
– Radiation therapy has proven beneficial in the treatment of extensive disease
23. Cont’d
▪ SystemicTherapy
– Steroids have been shown to be active in the management of thymomas
– Both single-agent and combination therapy have demonstrated activity in the
adjuvant and neoadjuvant settings
– Doxorubicin, cisplatin, ifosfamide, corticosteroids, and cyclophosphamide all
have been used as single-agent therapy
▪ MolecularlyTargetedTherapy
– Overexpression of c-kit is common in thymic carcinoma
– Coamplification of the HER-2/neu topoisomerase 2-alpha gene may correlate
with response to the CAP chemotherapy regimen
– antitumor activity has been reported with dasatinib, a small molecule oral,
multitargeted kinase inhibitor of Bcr-Abl and src kinases, ephrin receptor
kinases, platelet-derived growth factor receptor, and c-kit, in thymoma
24.
25.
26. Branches of the internal thoracic arteries are divided to permit the en bloc specimen to be
rotated upward, exposing the undersurface of the gland and the draining veins.The exposed
brachiocephalic and thymic veins are isolated and divided between ligatures or clips (inset).
27. Preoperative
▪ Initial workup:
– careful history and physical examination the neck and particularly the thyroid
gland require careful palpation
▪ Investigation:
– complete blood count,
– serum electrolytes,
– thyroid function tests,
– acetylcholine-receptor antibody assay,
– pulmonary function tests,
– electromyographic studies,
– immunoglobulin assay,
– bone marrow biopsy,
– cervical lymph node biopsy
28. Cont’d
▪ Radiographic Investigation:
– PlainChest X Ray 2 plane: posteroanterior and left lateral view
– CT Scan
– MRI
▪ Patient's strength and respiratory status should be optimized with
the use of pyridostigmine and immunosuppressive agents when
indicated
▪ Preoperative plasmapharesis or IV immunoglobulin therapy may be
beneficial in patients with a vital capacity of less than 2 L
29. Postoperative
▪ Usually are extubated in the OR within 30 minutes of the conclusion
of the operation
▪ Kept in a monitored setting overnight
▪ If the patient does not have an epidural catheter in place, parenteral
analgesia can be administered in small intermittent doses of
hydromorphone or morphine
▪ On the morning after the operation, oral medication and a clear
liquid diet are begun and advanced as tolerated
▪ The chest tubes are removed when no air leak or significant output is
present and the lungs are fully expanded on chest x-ray 2nd
postoperative day
30. Cont’d
▪ Antibiotics and the continuous epidural infusion are discontinued,
and oral narcotic analgesics are started once the chest tubes are
removed
▪ Patients with MG are discharged when their symptoms are
adequately controlled with oral medication and they are well able to
tolerate a regular diet
▪ Most patients are able to return to normal activity and work within 2–
3 weeks after transsternal thymectomy
▪ Tapering of medications in patients with MG begins at various times
after operation depending on the judgment of the neurologist
31. Substernal Goiter
▪ Goiters usually are considered substernal (also referred to as
mediastinal, intrathoracic, or retrosternal) when more than 50% of the
thyroid parenchyma is located below the sternal notch
▪ Mediastinal goiters are classified as primary or secondary
▪ Primary mediastinal goiters, also referred to as ectopic or aberrant
goiters, uncommon, 1% of all surgically excised goiters
▪ Secondary mediastinal goiters are a much more common, 5–15% of
all goiters demonstrate some extension into the mediastinum
34. Consideration for Thoracotomy
▪ Atypical anatomy
▪ Extramediastinal extension with known malignancy
▪ Posterior location or extension of tumor
▪ Goiters that extend to the tracheal carina
▪ Adherence to visceral or intrathoracic parietal pleura
35. Consideration for Median Sternotomy
▪ Primary retrosternal/ectopic
goiter
▪ Atypical anatomy
▪ Dense adhesions from prior
surgery
▪ Inability to deliver the gland
into the neck
▪ Extracapsular extension or
known mediastinal malignancy
▪ Recurrent intrathoracic goiter
▪ Prior thyroid surgery, especially
for cancer
▪ Goiters that extend to the
tracheal carina
▪ Goiters that cause life-
threatening compression of
mediastinal structures
▪ Significant intraoperative
mediastinal bleeding
▪ Adherence to mediastinal
pleura
36.
37. Goiters usually can be removed via cervical incision with the use of careful blunt
finger dissection to mobilize the gland from its attachment to mediastinal
structures. Most large goiters can be removed through a 2-cm collar incision.
38.
39.
40. Preoperative
▪ Radiographic:
– Chest x-ray mediastinal mass, superior mediastinal widening, tracheal
deviation or compression
– Chest CT scans define the full extent and anatomic relationships of the
substernal thyroid to surrounding structures and to facilitate preoperative
planning
▪ serum thyroid-stimulating hormone measurement If
hyperthyroidism is present antithyroid medications and beta
blockade should be undertaken before elective resection
▪ Pulmonary functiong testing is useful
▪ discuss these patients with the anesthesiologist in advance of
surgery
41. Postoperative
▪ Length of stay for an uncomplicated procedure is overnight
▪ patients can be discharged uneventfully with calcium or calcitriol
supplementation
▪ If a thoracotomy or sternotomy is required, length of stay is
increased
▪ major complications injury to the trachea, parathyroid glands, or
recurrent laryngeal nerves
▪ The need for tracheostomy is rare
42. Germ Cell Tumors
▪ Arise from primordial germ cells that fail to complete the migration
from the urogenital ridge and rest in the mediastinum
▪ Anterosuperior mediastinum is the most common extragonadal
primary site
▪ The current recommendations for evaluating the testes of a patient
with mediastinal germ cell tumor are:
– careful physical examination
– ultrasonography of the testes.
▪ Biopsy is reserved for positive findings
43. Teratomas
▪ The most common mediastinal germ cell neoplasms
▪ Usually located in the anterosuperior mediastinum
▪ Composed of multiple tissue elements derived from the three primitive
embryonic layers
▪ The peak incidence is in the second and third decades of life
▪ Radiographic evidence of normal tissue (e.g., well-formed teeth or globular
calcifications, a fatty mass) in an abnormal location can be considered
specific
▪ The teratodermoid (dermoid) cyst is the simplest form of a teratoma and
composed of derivatives of the epidermal layer, including dermal and
epidermal glands, hair, and sebaceous material
44. Cont’d
▪ Diagnosis and therapy rely on surgical excision
▪ For benign tumors that are so large or with involvement of adjacent
mediastinal structures so that complete resection is impossible
partial resection (debulking) can lead to the resolution of symptoms,
frequently without relapse
▪ Malignant teratomas chemotherapy and radiation therapy,
combined with surgical excision
▪ Overall prognosis is poor for malignant teratomas
45. Malignant Nonteratomatous Germ Cell
Tumors
▪ Occur predominantly in the anterosuperior mediastinum with a
marked male predominance
▪ Usually in the third and fourth decades of life
▪ Symptoms: chest pain, cough, dyspnea, and hemoptysis
▪ The superior vena cava syndrome occurs commonly
▪ Diagnostic imaging: A large anterior mediastinal mass
▪ CT and MRI are helpful to define the extent of disease and
involvement of mediastinal structures
46. Cont’d
▪ Serologic measurements (α-fetoprotein and β-hCG) useful for:
– differentiating seminomas from nonseminomas tumors,
– assessing response to therapy,
– diagnosing relapse or failure of therapy
▪ Seminomas rarely produce β-hCG and never produce α-fetoprotein
▪ More than 90% of nonseminomas secrete one or both of these
hormones
▪ seminomas are radiosensitive and nonseminomas are relatively
radiosensitive
47. Seminomas
▪ Constitute 50% of malignant germ cell tumors
▪ Usually remain intrathoracic
▪ Symptoms are related to the mechanical effects of the tumor on
adjacent mediastinal and pulmonary structures
▪ SuperiorVena Cava syndrome occurs in 10% to 20% of patients.
▪ Sensitive to irradiation and chemotherapy
▪ Treatment consists of systemic and local therapy:
– chemotherapy with salvage surgery
– combined chemoradiotherapy
48. Cont’d
▪ Radiation therapy may be considered for early-stage disease, but is
not recommended for regional disease
▪ Platinum-based chemotherapy is common
▪ Occasionally, excision is possible without injury to vital structures and
can be recommended
▪ When complete resection is possible, the use of adjuvant therapy is
unnecessary
49. Nonseminomatous Tumors
▪ Malignant nonseminomatous germ cell tumors include:
– choriocarcinomas,
– embryonal cell carcinomas,
– immature teratomas,
– teratomas with malignant components,
– endodermal cell (yolk sac) tumors
▪ Occur mostly in men in their third or fourth decade
▪ Diagnostic imaging: large anterior mediastinal mass with frequent
extension to the lung, chest wall, and mediastinal structures
50. Cont’d
▪ Mediastinal nonseminomas, but not testicular germ cell tumors, are
associated with the development of hematologic malignancies:
– acute megakaryocytic leukemia,
– systemic mast cell disease,
– malignant histiocytosis
– Myelodysplastic syndrome
– idiopathic thrombocytopenia refractory to treatment.
▪ Current treatment: cisplatin and etoposide-based regimens
▪ When tumor necrosis or a benign teratoma is found during surgical
exploration after chemotherapy excellent or intermediate
prognosis
51. Lymphomas
▪ Hodgkin’s and non-Hodgkin’s lymphoma are distinct clinical entities
with overlapping features
▪ Symptoms: chest pain, cough, dyspnea, hoarseness, and superior
vena caval syndrome
▪ Nonspecific systemic symptoms: fever and chills, weight loss, and
anorexia
▪ Symptoms characteristic of Hodgkin’s lymphoma chest pain after
consumption of alcohol and the cyclic fevers
52. Cont’d
▪ Surgeon’s primary role is to provide sufficient tissue for diagnosis
and to assist in pathologic staging.
▪ Thoracoscopy, mediastinoscopy, or mediastinotomy and, rarely,
thoracotomy or median sternotomy may be necessary to obtain
sufficient tissue
▪ Lymphoblastic lymphoma occurs predominantly in children,
adolescents, and young adults and represents 60% of cases of
mediastinal non-Hodgkin’s lymphoma.
53.
54. Neurogenic Tumors
▪ Usually located in the posterior mediastinum
▪ Originate from:
– The sympathetic ganglia (ganglioma, ganglioneuroblastoma, and
neuroblastoma)
– intercostal nerves (neurofibroma, neurilemoma, and neurosarcoma)
– paraganglia cells (paraganglioma)
▪ Peak incidence occurs in adults but it make up a proportionally
greater percentage of mediastinal masses in children
▪ Most neurogenic tumors in adults are benign but a greater
percentage of neurogenic tumors are malignant in children.
55. Schwannoma / Neurilimoma
▪ The most common neurogenic tumor
▪ Originates from perineural Schwann cells
▪ benign, slow-growing neoplasms, frequently arise from a spinal
nerve root, but can involve any thoracic nerve, well circumscribed
and have a defined capsule
▪ Peak incidence: third through fifth decades of life
▪ Many are asymptomatic
▪ Pain occur from compression or invasion of intercostal nerve, bone,
and chest wall
56. Cont’d
▪ cough and dyspnea are caused by compression of the
tracheobronchial tree
▪ Pancoast syndrome and Horner’s syndrome result from involvement
of t
▪ 10% of neurogenic tumors have extensions into the spinal columnhe
brachial and the cervical sympathetic chain dumbbell tumors
▪ MRI scan to evaluate the presence and extent of the tumor and its
relationship to the neural foramen and intraspinal space
▪ During resection, the intraspinal component should be removed first
via a posterior laminectomy minimizes the potential for spinal
column hematoma, cord ischemia, and paralysis
57. Magnetic resonance image of a neurogenic tumor with extension into the spinal canal
via the foramen, which gives a typical dumbbell appearance
58. Approach for dumbbell tumors.
A. Hemilaminectomy (black arrow).
B. Resection of intraspinal component
of tumor prior to thoracic approach
59. Neuroblastomas
▪ originate from the sympathetic nervous system
▪ most common location: retroperitoneum; however, 10% to 20%
occur primarily in the posterior mediastinum
▪ highly invasive neoplasms, frequently metastasized
▪ occur in children 4 years of age or younger.
▪ Therapy is determined by the stage of the disease
– stage I surgical excision
– stage II excision and radiation therapy
– stages III and IV multimodality therapy using surgical debulking, radiation
therapy, and multiagent chemotherapy
61. Ganglion Tumors
▪ Ganglioneuroblastomas composed of mature and immature ganglion cells
▪ Treatment from surgical excision alone to various chemotherapeutic strategies,
depending on:
– histologic characteristics,
– age at diagnosis,
– stage of disease
▪ Ganglioneuromas benign tumors originating from the sympathetic chain that are
composed of ganglion cells and nerve fibers
▪ typically present at an early age the most common neurogenic tumors occurring
during childhood
▪ usual location: paravertebral region; well encapsulated, cystic degeneration when
cross-sectioned
▪ Surgical excision is curative.
62. Preoperative
▪ Initial workup:
– physical examination and accurate history
▪ Imaging
– CT scan to define the morphology and location of the tumor, local invasion, bony or
airway involvement
– MRI to clarify the relationship of the tumor to the neural foramen and spinal canal
▪ Laboratory test:
– serum and urine free catecholamine levels
– Insulin and glucose levels
▪ Adjunctive workup:
– pulmonary function test
– cardiac risk stratification
63. Postoperative
▪ Patients are managed similarly to any patient who has undergone
thoracotomy or thoracoscopy
▪ Chest drains are removed early (i.e., on the day of surgery or
postoperative day 1) based on output and reexpansion of the lung
▪ extubated in the OR, and early mobilization is advocated
▪ Diet may be resumed in short order as tolerated
▪ patients with paragangliomas warrants special attention to heart
rate and blood pressure
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