Mediastinum and Trachea Flashcards by Mario Luna

Mediastinum and Trachea

Boders:

anterior?
posterior?
lateral?
floor?

sternum
vertebral column
lungs&pleura
diaphragm

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Mediastinum and Trachea

What structures form the roof of the mediastinum?

thoracic outlet at the level of first vertebra (rib and manubrium)

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Mediastinum and Trachea

What are the anatomic structures separating the anterior, middle, and posterior mediastinum?

None

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

trachea

middle

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

proximal great vessels

middle

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

thymus

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

lymph nodes

anterior and middle

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

esophagus

posterior

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

sympathetic chain ganglia, vagus nerve

posterior

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Mediastinum and Trachea

Anterior vs. middle vs. posterior

thoracic duct

posterior

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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

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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

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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

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Mediastinum and Trachea

Where does the lymph from the thymus drain?

lower cervical
hilar
internal mammary

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Thymoma

What is the peak decade of onset for patients with intercurrent myasthenia gravis?

Those without?

4th decade

7th decade

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Thymoma

What are the parathymic syndromes associated with thymoma?

Which is the most common?

MG
benign cytopenias
hypogammaglobulinemia
polymyositis

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Thymoma

Most common pattern of spread?

drop metastases

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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.

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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.

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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

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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)

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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

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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

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Thymoma

Identify the WHO (1999) type of thymoma.

Tumors have cytologic atypia and is distinctively unlike normal thymus
tissue.

type C

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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

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

Thymoma Identify: GETT staging Macroscopically encapsulated tumor, completely resected Surgeon suspects mediastinal adhesions and potential capsular invasion

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.