Mediastinal Masses Flashcards
Masses of Anterior/Superior Mediastinal Compartment
- Thymic neoplasm (thymoma, thymic carcinoma, carinoid)
- Lymphoma
- Germ cell tumors (teratoma, seminoma, non-seminoma tumor)
- Thyroid adenoma
- Parathyroid adenoma
Masses of Middle Mediastinal Compartment
- Bronchogenic cyst
- Pericardial cyst
- Enteric cyst
- Lymphoma
Masses of Posterior Mediastinal Compartment
- Neurogenic tumors
- Esophageal/Enteric cyst
- Lymphoma
Clinical presentation of mediastinal masses
- Asymptomatic and incidental (MC)
- Chest pain
- Cough
- Dyspnea
- Pain and Neurologic deficit (neurogenic tumor)
Diagnostic study of choice for mediastinal tumors
CT scan
(location, morphology, relationship to other structures)
Diagnostic approach to small (<5cm) tumors with characteristic features (i.e. thymoma, teratoma, benign cyst)
Surgical resection
Diagnostic approach to large mediastinal tumors
- CT-guided percutaneous biopsy
- Open biopsy
- Cervical mediastinoscopy
- VATS
- Chamberlain mediastinoscopy
- Thoracotomy
Serum tumor markers that much be checked for mediastinal masses (anterior)
- Beta-HCG
- AFP
- LDH
Diagnostic algorithm for anterior mediastinal masses
- CXR
- Chest CT
- Tissue biopsy (percutaneous vs. open)
- Serum tumor markers (Beta-HCG, AFP, LDH)
Tumors are most common in what mediastinal compartment
Anterior compartment
95% of all anterior mediastinal compartment tumors include:
- Four “Ts”
- Thymoma (MC)
- Teratoma (germ cell tumor)
- “Terrible” lymphoma
- Thyroid goiter
MC anterior mediastinal tumor
Thymoma
Clinical presentation of thymoma
- M:F (1:1)
- 30-50 years old
- 50% = asymptomatic/incidental
- 50% = symptomatic (pain, dyspnea, cough, horseness)
Thymoma associated syndromes
- Myasthenia gravis
- Red cell hypoplasia
- Hypogammaglobulinemia
- SLE
- Rheumatoid arthritis
- UC
- Thyroiditis
CT characteristics of benign thymoma
- < 5 cm
- round
- well-circumscribed
CT characteristics of malignant thymoma
- > 5 cm
- Irregular shape
- Invade neighboring structures
Treatment of choice for all thymoma
- Complete excision
- En bloc resection
- Pleura
- Pericardium
- Innominate vein
- SVC
- Lung
- Can excise one phrenic nerve and dissect tumor off other
- En bloc resection
Thymoma
Definition of surgically resectable
Surgery is indicated as the initial treatment for patients in whom a complete, R0 resection is considered feasible, ie, those with
- Completely encapsulated tumors or
- those with tumors invading readily resectable structures, such as the mediastinal pleura, pericardium, or adjacent lung.
Treatment of Stage I and Stage II Thymoma
Treatment of stage I and stage II thymoma is surgery, which may be followed by radiation therapy.
Treatment of stage III and stage IV thymoma that may be completely removed by surgery
Surgery followed by radiation therapy.
Neoadjuvant chemotherapy followed by surgery and radiation therapy.
Treatment of stage III and stage IV thymoma that cannot be completely removed by surgery
Chemotherapy.
Chemotherapy followed by radiation therapy.
Neoadjuvant chemotherapy followed by surgery (if operable) and radiation therapy.
Thymoma
Indications for Postoperative radiation therapy
*Stage I thymoma (Masaoka stage I to II)
-For patients with no capsular invasion, we offer observation given the low risk of recurrence and lack of overall survival benefit with postoperative RT (PORT). Such patients should be followed with annual imaging of the chest (computed tomography [CT]/magnetic resonance imaging [MRI]) for a minimum of ten years due to the risk of late recurrences. (See ‘Surveillance after treatment’ below.)
-For patients with invasion into the mediastinal fat or pleura and microscopic or grossly positive surgical margins, we suggest the addition of PORT, as this approach reduces the risk of recurrence to that of patients with R0 resections and lower-risk features. However, observation is an appropriate alternative given limited data. (See ‘Surveillance after treatment’ below.)
*Stage II to III thymoma (Masaoka stage III) – PORT is indicated in such patients given a higher risk of local recurrence.
*Stage IV thymoma (Masaoka stage IV) – RT should be individualized to the needs of the patient. RT can be used for palliation and possibly as curative therapy in oligometastatic disease.
MC surgical exposure/approachs for thymectomy
Median sternotomy
Cervical
VATS
Thymoma Staging (5-Yr Survival)
Survival based on Stage
- Stage I (95%)
- completely encapsulated
- Stage II (85%)
- IIa: mediastinal fat/pleura
- IIb: through capsule
- Stage III (70%)
- direct invasion of adjacent organ
- Stage IV (50%)
- IVa: pleura/pericardium mets
- IVb: distant mets
Thymoma
Indications for neoadjuvant/adjuvant therapy
Stage III-IV disease
Chemotherapy is offered in the neoadjuvant setting for those with potentially resectable thymoma or thymic carcinoma, or as primary therapy (with or without RT) for those with unresectable thymoma or thymic carcinoma.
Thymoma
Neoadjuvant/Adjuvant therapy regimen
Cisplatin-based chemotherapy + XRT
Mechanism of action of Myasthenia Gravis
Autoantibodies to ACh receptor
(decreased transmission of AP at the NM junction)
Demographics of Myasthenia Gravis
- 2x MC in women
- 2-3rd decade of life
Myasthenia Gravis Symptoms Grades
- Grade I: focal disease-ocular muscle weakness
- Grade II: Mild-moderate generalized disease
- Grade III: Severe generalized disease
- Grade IV: life-threatening weakness - respiratory failure
Confirmatory tests for Myasthenia Gravis
Endrophonium (short acting anticholinesterase ) test
ACh Receptor assay
Medical treatment for Myasthenia Gravis
Pryidostigmine (long-acting anticholinesterase)
Plasmapheresis and IVIg
Preop Mgmt for the patient with myasthenia gravis: Anticholinesterase agent
- We suggest continuing anticholinesterase agents (ie, pyridostigmine or neostigmine) up to and including the morning of surgery.
*
Preop Mgmt for the patient with myasthenia gravis: Immunomodulating therapy
- In the occasional patient with persistent mild residual respiratory impairment or dysphagia despite treatment with pyridostigmine and immunotherapy (eg, glucocorticoids), we administer a course of IVIG (2 grams/kg over two to five days) or plasmapheresis (three to five exchanges over 7 to 14 days) preoperatively.
- This practice is empiric, with a goal of reducing the risk of a postoperative flare evolving quickly into myasthenic crisis.
*** Treatment should be timed to end the week prior to surgery so that the effects of the rapid therapy peak and persist through the perioperative period. **
Myasthenia Gravis
Induction and maintenance of anesthesia
- NMBAs should be avoided when possible.
- If NMBAs are necessary, we suggest the use of rocuronium or vecuronium, and then reversal with sugammadex.
Myasthenia Gravis
Response to Depolarizing neuromuscular blocking agents
Patients with MG are resistant to neuromuscular blockade with depolarizing NMBAs (eg, succinylcholine), possibly because they have a decreased number of acetylcholine receptors [27,28]. T
Myasthenia Gravis
Response to Nondepolarizing neuromuscular blocking agents
Patients with MG are extremely sensitive to nondepolarizing NMBAs (eg, rocuronium, vecuronium, cisatracurium). Very small doses and residual drug effect may result in respiratory distress or loss of airway protection after emergence from anesthesia.
Indications for thymectomy for Myasthenia Gravis
- Presence of thymic hyperplasia or thymoma
- 30-50% of patients with thymoma have MG
- 10-15% of patients with MG have a thymoma
- Grade II-III MG
When should thymemctomy NOT be performed for Myasthenia Gravis
Myasthenic crisis
Grade IV disease
Prevelence of primary mediastinal lymphoma
Rare (5-10% of anterior mediastinal masses)
Most common lymphoma subtype presenting as mediastinal mass
T-cell Non-Hodgkin’s lymphoma
(Hodgkins and lymphoblastic lymphoma also present in mediastinum)
Diagnostic w/u for suspected mediastinal lymphoma
- H&P
- CXR
- Chest CT
- Tissue biopsy (percutaneous vs. open)
Survival for lymphoma based on __
Tumor grade
Treatment of lymphoma presenting in mediastinum
Chemotherapy and XRT
(Role of surgery: histologic diagnosis)
Role of surgery for lymphoma presenting in mediastinum
Histologic diagnosis
Prevelence of germ cell tumors among mediastinal masses
10-15% of mediastinal masses
Most common germ cell tumor in mediastinum
Teratoma
- Assymptomatic (MC)
- M:F (1:1)
Characteristics of tertaoma
- Assymptomatic (MC)
- May present with infection or rupture into pleura or airway (coughing of hair or sebum)
- M:F (1:1)
- Serum tumor markers negative
- Bx: well differentiated tissue from more than one cell line
Treatment of Choice for teratoma
Surgical excision
Most common malignant germ cell tumor of mediastinum
Seminoma
(males in 3rd decade)
Most common patient population with mediastinal Seminoma
Males in 3rd decade of life
Diagnostic features of Seminoma
- Slightly elevated Beta-HCG
- CT: characteristic large, homogenous mass with smooth boarders
- Slow growth
TOC of Seminoma
Chemo/XRT
XRT sensitive (primary treatment)
Cisplatin-based chemotherapy (metastatic disease)
(Surgical resection reserved to residual disease, manifested as local growth of residual mass)
Role of surgery for Seminoma
Residual disease manifested as local growth of a residual mass
(after XRT/chemotherapy)
Characteristics of Non-seminomatous germ cell tumors of mediastinum
- Young men (20-30 years old)
- Elevated B-HCG, AFP, LDH
- Rapid growth
- Compress neighboring structures (symptomatic)
- Metastatic disease common at presentation
- Overall prognosis poor
Three main subtypes of non-seminomatous GC tumors
(In order of frequency)
- Yolk sac carcinoma
- Embryonal carcinoma
- Choriocarcinoma
1st line treatment of non-seminomatous GC tumors
Cisplatin-based chemotherapy
(Surgical resection of residual tumor, regardless of response in tumor markers)
Surgical approach for removal of most intrathoracic goiters
Cervical incision (upper sternal split may be required)
MC middle mediastinal mass
Cysts
(bronchogenic, pericardial, enteric)
MC cyst in middle mediastinum
Bronchogenic cysts (60%)
Characteristics of bronchogenic cysts
- Associated with airway
- MC location = posterior to carina (subcarinal)
- Symptoms of airway/esophageal compression; infection of the cyst
Treatment of choice for bronchogenic cysts
Complete transthoracic surgical resection; even if asymptomatic to avoid future complications.
Definition of pericardial cysts
Rare, benign cysts occuring at cardiophrenic angle (most often on right)
Most common location for pericardial cysts
Right cardiophrenic angle
Characteristics of pericardial cysts
- CT imaging of thin, non-enhancing wall
- Content has density similar to water
TOC: pericardial cysts
Aspirate:
Surgical resection (symptomatic)
(Some argue for surgical resection of all pericardial cysts to avoid potential for rupture, erosion, or compression of heart or great vessels)
Prevalence of neurogenic mediastinal tumors
15-20% of all mediastinal tumors
Classic presentaiton and Cell of Origin of neurogenic mediastinal tumors
Presentation: Pain or neurologic dysfunction
Cell of origin: Neural Crest Cell
3 major subtypes of Neurogenic tumors
- Nerve sheath tumors
- Ganglion cell tumors
- Paraganglionic tumors
MC neurogenic tumors
Nerve sheath tumors (40-70%)
Most common location of nerve sheath tumors
Costovertebral/paravertebral sulcus
Characteristics of nerve sheath tumors
- Usually benign
- neurofibrosarcoma (malignant variant)
- increased mitotic activity
- lack of encapsulation
- neurofibrosarcoma (malignant variant)
- 2 MC histologic types (schwannoma and neurofibroma)
Neurogenic tumor that arises from sympathetic chain and adrenal medulla
Ganglion cell tumor
Benign and Malignant subtypes of Ganglion cell tumor
Benign: ganglioneuroma (secrete VIP)
Malignant: Ganglioneuroblastoma
Neurogenic tumors that secretes VIP
Ganglioneuroma (benign ganglion cell tumor)
Ganglioneuroblastoma (malignant ganglion cell tumor)
MC extracranial malignancy in children and most aggressive ganglion cell tumor
Neuroblastoma
(secrete VIP and catacholamines)
TOC for neuroblastoma
Surgical resection (localized disease) + adjuvant chemoradiation for residual diseaes
Factors associated with poor prognosis for neuroblastoma
- Metastatic disease
- Age < 18 months
- Histolgic differentiation
- DNA ploidy
- Presence of residual disease
- N-myc amplification
- High levels of neuron-specific enolase and LDH
Tumors that arise from paraganglionic tissues in costovertebral area
Paraganglionic tumors
Subtypes of paraganglionic tumors
Pheochromocytomas (catacholamine secretion_
Chemodectomas (hormonally inactive)
TOC for paraganglionic tumor
Surgical resection (tumor capsule should be left intact)
(Chemodectomas respond to XRT)
Name the Mass

Thymoma
Name that mass

Well-differentiated teratoma
Name that mass?

mediastinal lymphoma
Name that Mass?

Mediastinal seminoma
Name that mass?

Mediastinal Non-seminoma
Name that Mass?

Bronchogenic cyst
Masaoka staging
- I
- IIa
- IIb
- III
- IVa
- IVb

Thymoma: treatment based on masaoka stage:
I
IIa
IIb
III
IVa
IVb

Venous and arterial blood supply of the thymus.
Blood supply to the thymus comes from the internal thoracic artery as well as the superior and inferior thyroid arteries.
Drainage is to the left innominate vein as well as the superior, middle and inferior thyroid veins.
Thymoma: “Recommended follow-up protocols by ITMIG”
