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THYMIC TUMORS

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Secondary to neurogenic tumor in mediastinal tumor. Rare in children ... Brachytherapy with I-125 seed placed in gross residual disease at time of operation. ... – PowerPoint PPT presentation

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Title: THYMIC TUMORS


1
THYMIC TUMORS
  • GENERAL THORACIC SURGERY
  • CHAPTER 167

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Thymic tumor
  • Almost in the anterior mediastinum.
  • Secondary to neurogenic tumor in mediastinal
    tumor.
  • Rare in children younger than 16 y/o.

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Thymic tumor
  • Separated into three histologic categories
  • Thymoma.
  • Thymic carcinoma.
  • Neuroendocrine tumor.

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THYMOMA
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Location
  • 95 in anterior mediastinum.
  • Neck.
  • Left hilar region.
  • Within lung parenchynma.
  • Anterior cardiophrenic angle.

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Pathology
  • All thymoma derive from thymic epithelial cell.
  • Predominantly lymphocytic thymoma (more than 66
    lymphocyte).
  • Predominantly epithelial thymoma (more than 66
    epithelial cell).
  • Mixed lymphoepithelial thymoma.
  • Spindle cell tumor.

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Pathology
  • Most important gross feature The presence or
    absence of encapsulation of tumor and the gross
    invasion into adjacent structure.
  • The invasion present The thymoma must be
    considered malignant lesion regardless the
    microscopic appearance.
  • Extensive spread.
  • Incidence of distal metastasis is 3.
  • Stage.

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Another class
  • Cortical.
  • Medullary.
  • Mixed thymoma.
  • Immunohistochemistry.

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Clinical presentation
  • 50-60 y/o.
  • Sex distribution Equal.
  • s/s chest pain, SOB, cough, SVC syndrome,
    paralysis of hemidiaphragm, hoarseness, weight
    loss, fatigue, fever, night sweats.

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Parathymic syndrome
  • 40 with parathymic syndrome.
  • Myasthenia gravis.
  • Pure red cell aplasia.
  • Immunoglobulin deficiency.
  • Systemic lupus erythematosusinfrequently, 2.5,
    poor prognosis.
  • Nonthymic cancer17-21.
  • Inappropriate antidiuretic hormone
    secretion(SIADH)-- rarely, malignant thymoma and
    spindle cell thymoma.

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Myasthenia gravis
  • Most commonly associated disease.
  • 30 of patient with thymoma associate with MG.
  • Only 5-15 patient with MG have thymoma.
  • 10-15 older than patient with MG without tumor,
    younger than patient with thymoma without MG.
  • Any type of thymoma except spindle type, marked
    associated squamous elements in thymus.
  • Little affect on local presention, clinical
    behavior, prognosis.
  • Better prognosis than patient with thymoma
    without MG.

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Pure red cell aplasia
  • Anemia.
  • Suppression erythrogenesis in bone marrow.
  • Mechanism--Not clear, IgG antibodies inhibit
    erythropoietin or hemoglobin synthesis, cytotoxic
    to erythroblast, decrease B cell.
  • 50 patients with red cell aplasia have thymoma,
    5 thymoma with red cell aplasia.
  • Most (70)are non-invasive spindle cell.
  • 25-33 patient with red cell aplasia benefit from
    excision of the thymoma.

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Immunoglobulin deficiency
  • Spindle cell type.
  • Acquired hypogammaglobulinemia.
  • Suppressor T-cell inhibiting immunoglobulin
    synthesis.

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Diagnostic studies
  • Standard posteroanterior and lateral chest
    radiographies.
  • CXRSmooth or lobulated mas, right side the
    silhouette sign present, left side the sign
    abscent.
  • Calcification 10.
  • CTDelineate the extent of mass, cannot not
    differentiating benign and malignant, assessing
    intrathoracic spread of an invasive thymoma.

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Surgical biopsy
  • Unnecessary for a suspected locally symptomatic
    thymoma, because the capsule of tumor may be
    violated by invasive procedure.
  • Only distinguish the tumor from the other
    malignant tumor, or locally symptomatic, clearly
    nonresectable, biopsy is to establish the
    diagnosis before making decision of therapy.
  • Fine needle biopsy by CT or sono-guide.
  • Extend substernal mediastinoscopy.
  • Anterior mediastinotomy.
  • Lateral thoracotomy.
  • VATS.

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Treatment
  • Depend on clinical presentation.
  • Surgical resection thymoma is encapsulated and
    free from adjacent structure.
  • Radiation in atage II, III.
  • chemotherapy in locally nonresectable, presence
    distal metastasis, neoadjuvant therapy for
    initially advanced local diasease or in locally
    recurrent disease.

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Surgical excision
  • All patient with thymoma should undergo as
    complete resection as possible.
  • Pulmonary lesion should be excised at the same
    time.
  • Tumor encapsulated total thymectomy.
  • Simple enucleation is avoid except the unusual
    condition(excision through lateral thoracotomy
    with unknown preoperative diagnosis).

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Surgical excision
  • Preferred median sternotomy.
  • Posterolateral thoracotomy for large tumor in
    hemithorax or tumor from anterior cardiophrenic
    angle.
  • Bilateral anterior fourth intercostals
    incisionwith transverse section of sternum
    (clamshell) for large midline tumors.
  • The use of video-assisted thoracoscopic removal
    of thymoma is unacceptable even for stage I
    tumor.

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Surgical excision
  • Extend procedure the entire thymus and adjacent
    fat should be removed if possible.
  • Tumor fixation to nonvital adjacent structure
    should be resect(pleura, lung, pericardium, ).

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Surgical excision
  • One phrenic nerve involve could be resected if
    patient could tolerate loss of hemidiaphragm
    function.
  • If both phrenic are involved, only debulking is
    performed.

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Surgical excision
  • The wall of SVC involve if no SVC syndrome,
    lateral wall resection of SVC and replace graft.
  • When the aorta, major pulmonary vessels,
    recurrent nerve trachea, are involve, only
    debulking.
  • Operative mortality 3.1-7.7.

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Radiation therapy
  • For invasive thymoma.
  • In stage I is uncertain.
  • For resected stage II or completely or
    incompletely resected stage III disease.
  • 4500-5000 cGy for suspected microscopic residual
    disease.
  • 6000 cGy for known residual disease.
  • Brachytherapy with I-125 seed placed in gross
    residual disease at time of operation.

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Chemotherapy
  • For stage III and IV.
  • Cisplatin, doxorubucin, vincristine,
    cyclophosphamide, neoadjuvant.

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Treatment of recurrent local disease or distant
metastases
  • Recurrent I 0-5, II 10, III 30, IVa
    33.
  • Second resection if possible.
  • 5-year survival is 65.
  • For stage III recurrent irradiation or
    chemotherapy.

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Survival
  • Depend on stage, tumor size, histology, extent
    of resection.
  • Better in patient with thymoma associated with
    MG.
  • Poor in patient with red cell aplasia,
    hypogammaglobulinemia, SLE.

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Thymic carcinoma
  • Low and high grade.
  • Malignant cytologic and architectural feature.
  • Staging not standardized.

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Squamous cell carcinoma
  • Most common.
  • Men predominant.
  • 60 y/o.
  • Partially encapsulated.
  • s/s weight loss, chest pain, cough, hemoptysis.
  • TreatmentSurgical resection, sensitive to
    radiation, combination chemotherapy.
  • Prognosis excellent in well-differentiated
    squamous cell carcnoma.

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Lymphoepitheliomalike carcinoma
  • Epstein-Barr virus.
  • Treatmentirradiation therapy, chemotherapy.

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Tumor of neuroendocrine cell origin
  • Thymic carcinoid tumor.
  • Small cell carcinoma.

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Thymic carcinoid tumor
  • Large.
  • One-half lesion infiltrative into adjacent
    structures.
  • Associated Cushings syndrome.
  • 3/4 are men.
  • Mean age 42 y/o.
  • s/s asymptomatic, chest pain, cough dyspnea,
    SVC syndrome, fatigue fever, night sweat.

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Thymic carcinoid tumor
  • 1/3 have feature of Cushing sundrome ectopic
    ACTH production.
  • 15-18 with multiple endocrine neoplasia(MEN)syndr
    ome.
  • Most MEN I.
  • Few MEN II.
  • Thymic carcinoid associated with MEN syndrome is
    more malignant in behavior.
  • 1/3 with bone metastases.

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Multiple endocrine neoplasia(MEN)
  • MEN I(Werner syndrome) Single or multiple
    parathyroid adenoma, islet cell tumor of
    pancrease, adrenal neoplasm, thyroid adenoma,
    multiple lipoma.
  • MEN II(Sipple syndrome)Thyroid medullary
    carcinoma, pheochronocytoma, parathyroid
    neoplasia.

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Thymic carcinoid tumor
  • Treatmentcomplete surgical resction or debulking
    tumor, radiation therapy.
  • 73 local recurrence or metastases.
  • Overall cure rate is low 13.
  • Mean survival of metastases disease is 3 years.

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Small (Oat)cell carcinoma
  • Aggressive and metastases extensively,
  • Associated with MEN I.
  • Treatmentradiation therapy and chemotherapy.
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