Mediastinum and Trachea Flashcards
Mediastinum and Trachea
Boders:
anterior?
posterior?
lateral?
floor?
sternum
vertebral column
lungs&pleura
diaphragm
Mediastinum and Trachea
What structures form the roof of the mediastinum?
thoracic outlet at the level of first vertebra (rib and manubrium)
Mediastinum and Trachea
What are the anatomic structures separating the anterior, middle, and posterior mediastinum?
None
Mediastinum and Trachea
Anterior vs. middle vs. posterior
trachea
middle
Mediastinum and Trachea
Anterior vs. middle vs. posterior
proximal great vessels
middle
Mediastinum and Trachea
Anterior vs. middle vs. posterior
thymus
anterior
Mediastinum and Trachea
Anterior vs. middle vs. posterior
lymph nodes
anterior and middle
Mediastinum and Trachea
Anterior vs. middle vs. posterior
esophagus
posterior
Mediastinum and Trachea
Anterior vs. middle vs. posterior
sympathetic chain ganglia, vagus nerve
posterior
Mediastinum and Trachea
Anterior vs. middle vs. posterior
thoracic duct
posterior
Mediastinum and Trachea
What is the most common type of mediastinal tumor that can arise in the anterior, middle, and posterior compartments?
What is the most common tumor of the anterior mediastinum?
Lymphoma
Thymoma
Mediastinum and Trachea
Embryologically, the thymus is derived from the endoderm of the lower portion of the ____ pharyngeal pouch and involutes during adulthood, gradually being replaced by adipose tissue.
third
Mediastinum and Trachea
What is the arterial blood supplier of the thymus?
What is/are the vein/s carrying venous drainage?
internal mammary arteries
innominate and internal thoracic veins
Mediastinum and Trachea
Where does the lymph from the thymus drain?
lower cervical
hilar
internal mammary
Thymoma
What is the peak decade of onset for patients with intercurrent myasthenia gravis?
Those without?
4th decade
7th decade
Thymoma
What are the parathymic syndromes associated with thymoma?
Which is the most common?
MG
benign cytopenias
hypogammaglobulinemia
polymyositis
MG
Thymoma
Most common pattern of spread?
drop metastases
Thymoma
Magnetic resonance imaging (MRI) can provide more detail when needed, delineating the musculoskeletal anatomy and neurovascular structures of the mediastinum.
MRI may also improve sensitivity for defining the soft tissue extent of the mass in addition to providing information regarding tumor grade and invasiveness beyond that which can be gleaned from CT.
What are the common features indicative of a high-grade tumor?
low T2-signal foci within the mass
the presence of mediastinal lymphadenopathy
an incomplete capsule
and inhomogeneous enhancement.
Thymoma
FDG-PET can differentiate thymoma from thymic carcinoma based on uptake.
TRUE or FALSE?
True.
thymic carcinoma tends to have significantly higher metabolic
activity.
Thymoma
Bernatz categorization based on cell types.
What are the 4 cell types?
(theoretical purposes since this is poorly correlated clinically with prognosis)
lymphocytic
epithelial
mixed
spindle cell
Thymoma
Verley and Hollman categorization based on predominant cell types.
What are the 4 cell types?
(theoretical purposes since this is poorly correlated clinically with prognosis)
spindle or oval
lymphocyte-rich
differentiated epithelial cell-rich
undifferentiated epithelial (thymic carcinoma)
Thymoma
Müller-Hermelink categorization based on subsets of epithelial cell of the thymus.
What are the 4 cell subsets?
(theoretical purposes since this is poorly correlated clinically with prognosis)
cortical
medullary
mixed
well-differentiated
Thymoma
Identify the WHO (1999) type of thymoma.
Tumors are composed of neoplastic oval or spindle-shaped epithelial cells without atypia or lymphocytes.
type A
Thymoma
Identify the WHO (1999) type of thymoma.
Tumors have cytologic atypia and is distinctively unlike normal thymus
tissue.
type C
Thymoma
Identify the WHO (1999) type of thymoma.
Tumors are composed of neoplastic oval or spindle-shaped epithelial cells with foci of lymphocytes.
Type AB
Thymoma
Identify the WHO (1999) type of thymoma.
Tumors resemble normal thymic cortex with areas
similar to thymic medulla.
Type B1
Thymoma
Identify the WHO (1999) type of thymoma.
Which is B2 and which is B3?
Tumors have scattered neoplastic epithelial cells
with vesicular nuclei and distinct nucleoli among a heavy population of
lymphocytes
Cells are predominantly round or polygonal epithelial cells exhibiting mild atypia
admixed with a minor component of lymphocytes
first is B2
Thymoma
Identify the WHO (1999) type of thymoma.
Well-differentiated thymic carcinoma
Type B3
Thymoma
Identify: Masaoka Stage
Macroscopic invasion into surrounding organs
III
Thymoma
Identify: Masaoka Stage
Pleural or pericardial implants/dissemination
IVa
Thymoma
Identify: Masaoka Stage
Lymphogenous or hematogenous metastases
IVb
Thymoma
Identify: Masaoka Stage
Macroscopically completely encapsulated, with no microscopic capsular invasion
I
Thymoma
Identify: Masaoka Stage
Microscopic invasion into the capsule
IIb
Thymoma
Identify: Masaoka Stage
Macroscopic invasion into surrounding mediastinal fatty tissue or mediastinal
pleura
IIa
Thymoma
Identify: GETT staging
Encapsulated tumor, completely resected
Ia
Thymoma
Identify: GETT staging
Macroscopically encapsulated tumor, completely resected
Surgeon suspects mediastinal adhesions and potential capsular invasion
Ib
Thymoma
Identify: GETT staging
Invasive tumor, completely resected
II
IIIa is STR
(IIIb is biopsy only)
Thymoma
Identify: GETT staging
Distant metastasis
IVb
IVa is distant pleural implants or supraclavicular implants
Thymoma
Identify: ITMIG TNM
pathologically observed microscopic invasion into mediastinal fat.
Can you name the others?
T1a
T1b - mediastinal pleura
t2 - pericardium
t3 - more resectable organs
t4 - less or unresectable organs
Thymoma
What are the two factors that have consistently demonstrated prognostic value in multivariate analyses in large studies?
tumor invasiveness (stage)
and
completenes/extent of resection
Thymoma
Patients older than 30 to 40
years may have a better prognosis than younger patients.
TRUE or FALSE?
True
Thymoma
What is the traditional definition of a bulky disease?
> 10 cm
Interestingly, although
bulky tumor size was classically defined in terms of a 10-cm threshold, a more
recent publication of 154 consecutive patients with thymic epithelial tumors
treated in the modern era (2000–2014) demonstrated that a size >4 cm was
associated with worse relapse-free survival, even among patients with stage I
disease
Thymoma
What is the most common pattern of failure?
locoregional
Thymoma
If technically feasible, what is the the traditional recommendation for recurrence?
surgery and adjuvant radiation
Thymoma
Recurrences arise within 3 to 7 years but may occur as late as 32 years after initial resection.
TRUE or FALSE?
True
Thymoma
For completely resected stage II thymoma, studies have been mixed with regard to local control benefit of adjuvant radiotherapy, with some studies showing trends toward better local control after adjuvant radiation, others finding no difference in recurrence rates, and one series reporting worse results with adjuvant radiation.
What additional risk factors are considered (by Haniuda et al) to benefit the most from PORT?
+ fibrous adhesion to the mediastinal pleura without microscopic invasion
Thymoma
Reviews of outcomes, retrospective studies, and single-institution studies are conflicting regarding the benefit of PORT to completely resected stage II or III thymomas, with majority reporting better local control but no survival benefit.
In an analysis of the NCDB by Jackson et al, PORT was associated with improved OS in what subset of patient?
IIB to III with positive margins
Thymoma
What is the mechanism of action of glucocorticoids that can explain response rates in resectable thymomas (47%)?
induce apoptosis in CD4+CD8+ immature thymocytes.
Thymoma
A prospective trial have shown that chemotherapy given in the neoadjuvant setting was associated with improved survival for stage IVb thymomas.
TRUE or FALSE?
False.
It’s III to IVa only
***
The most promising use of chemotherapy is in the neoadjuvant setting. Like
preoperative radiation, chemotherapy seems to render tumors more suitable for
complete resection. An early investigation suggested that neoadjuvant
chemotherapy was associated with improved survival for patients with stage III
or IVa thymomas. This hypothesis was more rigorously tested in a phase II
prospective trial by Park et al.: 27 patients with radiographic evidence of stage
III or IV thymic malignancies were enrolled (9 had thymoma and 18 had thymic
carcinoma)
Thymoma
RT dose, definitive RT
60 to 70 Gy/1.8 to 2
Thymoma
RT dose, + margins
54 Gy/1.8 to 2
Thymoma
RT dose, postoperative dose
45 to 50/1.8 to 2
Thymoma
Draining nodal distributions do not need to be included in the radiation fields.
TRUE or FALSE?
True.
Because thymomas do not routinely spread via the lymphatic system.
Thymoma
Definitive RT CTV
gross disease + 1-2 cm margin
Thymic Carcinoma
Thymic carcinoma is more common, more aggressive, and is more lethal than thymoma.
TRUE or FALSE?
False.
They are more aggressive but less common.
Thymic Carcinoma
Although incomplete resection does not necessarily preclude long-term survival if multimodality platinum-based therapy is used, complete resection is nevertheless the cornerstone of treatment.
TRUE or FALSE?
True
Thymic Carcinoma
Thymic carcinoma generally is less responsive to chemotherapy than thymoma.
TRUE or FALSE?
True.
Thymic Carcinoid
Thymic carcinoid (neuroendocrine) tumors of the thymus are very rare,
accounting for <5% of all neoplasms of the anterior mediastinum. They originate
from normal thymic ________ cells, which belong to the amine-precursoruptake-
and-decarboxylation group
Kulchitsky
Thymic Carcinoid
What syndromes are associated with roughly half of thymic carcinoids?
MEN-1
or
secondary Cushing syndrome
Mediastinal Germ Cell Tumors
Primary mediastinal germ cell tumors have the same morphologic and histologic appearance as those of the testes. These tumors of the mediastinum are less aggressive and have a better prognosis than their gonadal counterparts.
TRUE or FALSE?
False.
They are more aggressive and have poorer prognosis
Mediastinal Germ Cell Tumors
Which is less sensitive to chemotherapy and radiation, and overall has a poorer prognosis?
pure seminoma vs. nonseminomatous?
nonseminomatous
Thymic Tumors
Which one is associated more with MG?
Thymolipoma
Thymoliposarcoma
Thymolipoma
Mediastinal Mesenchymal Tumors
I. Mesenchymal lesions can arise in any of the three mediastinal compartments.
II. Mesenchymal tumors that present in adults seem to be more malignant than those presenting in children.
III. Mediastinal mesenchymal lesions can reach impressively large sizes before detection, typically presenting with symptoms such as chest pain and dyspnea.
Which is/are TRUE?
I and III.
II is other way around.
Mediastinal Mesenchymal Tumors
What is the most common mediastinal mesenchymal lesion?
lipoma
Mediastinal Mesenchymal Tumors
What is the most common curative treatment for lipomase?
GTR
***
Mediastinal lipomas are the most common of the mediastinal mesenchymal
lesions; they represent 1% to 5% of all lipomas.
Mediastinal lesions
can occur in isolation or in multiples and may mimic cardiomegaly or pleural
effusion on a chest x-ray.
They are usually well circumscribed and encapsulated but can grow to 20 cm in diameter before detection.
Though these tumors
can be quite large and cause significant compressive symptoms, gross total resection is almost always curative.
Technically, lipomas are
considered “benign” tumors, but those that are growing or causing symptoms
should be referred for surgical resection.
Mediastinal Mesenchymal Tumors
Where is the most common location of mediastinal liposarcomas?
posterior compartment.
***
In contrast to lipomas, liposarcomas consist of immature fat cells with malignant histology and behavior.
Distinguishing lipomas from liposarcomas can be difficult histologically; liposarcomas are distinguished by size heterogeneity, hyperchromatic nuclei, and eosinophilic cytoplasm.
Primary mediastinal liposarcomas often appear in the posterior portion of the mediastinum.
Anterior mediastinal liposarcomas are possible albeit rare.
Tumors often appear to be encapsulated and well circumscribed, even when invasion is present, giving rise to the term “pseudocapsule.”
In one historical review, survival times for patients with well-circumscribed lesions ranged from 3 to 17 years, whereas patients with grossly invasive tumors died within 2 years.
As is true for all sarcomas, the prognosis depends on the histologic grade. Like other sarcomas, optimal treatment consists of surgical resection and adjuvant radiation therapy.
Because well-differentiated tumors have little propensity for distant metastases, withholding adjuvant radiation for a trial of observation can be considered after an R0 resection, but the significant local recurrence rates of 20% to 30% should be acknowledged during multidisciplinary discussion and with the patient.
Mediastinal Mesenchymal Tumors
hemangiomas, hemangioendotheliomas, and hemangiopericytomas
A. Which are notable for high rates of metastasis at presentation?
B. Hemangiomas can be capillary or cavernous; cavernous hemangiomas (i.e., angiomyomas or hamartomas) are distinguished from capillary hemangiomas by the presence of _________.
A. Hemangioperictyomas
B. smooth muscles
Mediastinal Mesenchymal Tumors
What is the hallmark finding in hemangioendothelioma?
cytoplasmic Weibel-Palade bodies.
MPNST
What histopathologic factor is most reliably correlated with malignancy?
mitotic figures of 5 or more in 50 high-power fields.
Tracheal Cancer
What histologic subtype is usually equally distributed in both men and women, not asssociated with smoking, and present at younger ages?
adenoid cystic carcinomas
Tracheal Cancer
What are the bony landmarks for the superior and inferior borders of the trachea?
C6-7 to T4-6.
The upper border lies around the sixth or seventh cervical vertebra and the lower border around the fourth (full expiration) or sixth (full inspiration) thoracic vertebra.
Tracheal Cancer
What is the most common symptom?
cough (Yang et al.)
followed by dyspnea
Tracheal Cancer
Management
Resection + PORT
Tracheal Cancer
Most common dreaded adverse reaction to dose escalation in RT of tracheal malignancies?
treacheoesophageal fistula
Tracheal Cancer
Prophylactic/elective nodal irradiation is a mainstay of treatment especially if the histology is squamous cell.
TRUE or FALSE?
False.
***
The role of elective nodal irradiation for tracheal carcinoma is uncertain. As
mentioned earlier, nodal status does not seem to have prognostic significance;
even cervical adenopathy was not associated with poorer outcome.
Given the
low proclivity for lymphatic spread of adenoid cystic carcinomas, the choice to
avoid elective nodal irradiation for this variant is certainly reasonable. Because
local recurrence is the major factor influencing survival, nodal and regional
failure patterns are not a main concern. Yet, if mediastinal or cervical nodes are
seen on radiographic or pathologic examination, or if worrisome pathologic risk
features are discovered at surgery, radiation to these regions should be
considered.
