Mediastinal Diseases Flashcards
diagnostic problems for mediastinal pathology
the mediastinum is a confined space that is difficult to clinically evaluate and adequately biopsy
there are many organs in this small compartment that can have many different pathologic processes
What is the most common type of mediastinal tumors?
neurogenic tumors
thymoma
cysts
lymphoma
germ cell tumors
structures found in the mediastinum
thumas
parathyroids
heart
lungs
trachea
esophagus
great vessels
lymph nodes
intercostal nerves and sympathetic ganglia
supporting mesenchymal and bony structures and mesothelium
Where are malignant mediastinal tumors mainly found?
anterior/superior compartment
Major tumors of the superior mediastinum
four T’s:
thymoma
T-cell-rich lymphomas
teratomas (and other germ cell tumors)
thyroid (and parathyroid)
major pathological process of the middle mediastinum
bronchogenic/pericardial cyst
major pathological processes of the posterior mediastinum
neurilemmoma
neurofibroma
ganglioneuroma/neuroblastoma
malignant PNST
major pathological processes of the anterior mediastinum
thymoma
germ cell tumors
malignant vs. benign tumors of the mediastinum
80% of asymptomatic processes are benign
25% of 40% of mediastinal tumors are malignant
diagnostic techniques for mediastinal masses.
CR and MRI
ultrasound
nuclear scan
methods for mediastinum biopsy
CT-guided needle biopsy
cervical mediastinoscopy and parasternal mediastinotomy
VATS - video-assisted thoracoscopy
open thoracotomy
What are the types of thymus hyperplasia?
true hyperplasia
follicular thymic hyperplasia
true hyperplasia
increase in all elements of th ethymus, so weight is greater than expected for age
compensatory hyperplasia observed after stressful events
follicular thymic hyperplasia
increase in B and T cells lymphodi follicles
observed in close to 75% o fpatients with myasthenia gravis and other autoimmune diseases
thymoma
most common tumor of the anterior and superior mediastinum
mostly asymptomatic, 1/3 have chest pain, cough, dyspnea, or superior vena cava syndrome
30-50% are associated with myasthenia gravis
histological classification of thymomas
generally benign
classified as spindled or epithelioid
Type A thymoma
spindle cell, good prognosis
Type B thymoma
B1 - lymphocyte-rich, scattered epithelial cells
B2 - lymphocytes = epithelial cells
B3 - epithelial-rich, scattered lymphocytes
B3>B2>B1 in terms of prognosis
Type C thymoma
thymic carcinoma
poor prognosis
Masaoka stage 1
completely encapsulated thymoma macroscopically and microscopically
Masaoka stage 2
thymoma macroscopically invades fatty tissue outside thymus, or microscopically invades through capsule
Masaoka stage 3
tumor macroscopically invades into neighboring organs such as great vessels, lung, or pericardium
Masaoka stage 4
lymphatic or hematogenous metastasis, or disseminated pleural/ericardial spread
treatment for thymomas
thoracotomy and complete excision
complete excision and radiotherapy with/without chemotherapy
primary lymphoma of mediastinum and types of disease found here
commonly located anteriosuperior, and less often, middle mediastinum
Hodgkin’s Lymphoma/Disease - most common
acute lymphoblastic leukemia/lymphoma (NHL) - most common in non-Hodgkin’s lymphoma in children/adolescents
mediastinal large cell lymphoma (B-cell type) - most common primary form of NHL in adults
Hodgkin’s Lymphoma
most common, presents in young adult females as an anterosuperior mediastinal mass
treated with chemotherapy and radiation
Reed-Sternberg cells are diagnostic in the histology
acute lymphoblastic leukemia/lymphoma
T-cell type
a rapidly progresssive lymphoma that quickly involves blood, and lymph nodes, and bone
found in children/adolescent males
SVC syndrome, respiratory distress
treat with intense chemotherapy and bone marrow transplant
mediastinal large cell lymphoma
B-cell type
found in young females
usually tumor confined to chest
majority go into complete remission with intensive chemotherapy wiht/without radiation
germ cell tumors
found in anterior mediastinum
subtypes include:
teratoma - most common
germinoma (seminoma)
other GCTs more commonly associatd with Klinefelter syndrome
teratoma
most common in adolescents
neonates and young children have good prognosis
in postpubertal patients prognosis is worse if associated with other malignant germ cells, immature elements, or somatic malignancy
histologic findings of teratoma
mucosa and skin adnexa with underlying mucinous glands
seminoma
most common malignant germ cell tumor
almost exclusively in males
most patients symptomatic, 10% have SVC
good prognosis if treated with chemotherapy or radiation
histology of seminomas
epithelioid cells with cleared (glycogenated) cytoplasm and large nuclei with nucleoli arranged in nests surrounded by fibrovascular stroma with lymphocytes
beta-HCG
high levels strongly suggest the presence of highyl aggressive choriocarcinoma
What is the marker for yold sac tumors?
high levels of serum alpha-fetoprotein
neuroendocrine tumors o fthe mediastinum
carcinoid tumors
located in the anteriosuperior mediastinum
35% functional, ACTH most comon hormone produced
prognosis is poor, particularly in patients with tumors exhibiting metastatic spread
histology of carcinoid tumors
epithelial cells with rounded nuclei having finely granular (salt and pepper) chromatin
rosette formation is common
neurogenic tumors
located in the posterior mediastinum
scwannoma is most common
neurofibroma is next - associated with neurofibromatosis type I
histology of as schwannoma
encapsulated, admixture of cellular Antoni A areas with Verocay bodies and hypocellular vascular antoni B areas
dumbbell shaped tumor that can occasionally extend inside the spinal canal
treated with complete resection
neurofibroma
condition associated with malignant peripheral nerve sheath tumors
plexiform neurofibroma and malignant schwannoma
histology of plexiform neurofibromas
distended and enlarged nerve fascicles composed of Schwann cells, fibroblasts, and neurites in a myxoid stroma
histology of malignant schwannoma
cellular fascicles of highly atypical spindled cells with irregular nuclear contours
stroma may be focally myxoid
ganglioneuroma
older children and adults
usually asymptomatic, but may be associated with diarrhea
diarrhea due to vasoactive intestinal polypeptide production by ganglion cells
histology of ganglioneuromas
fascicles of elongated Schwann cels and mature (but dysplastic) ganglion cells
cysts of the mediastinum
thymic cyst
pericardial cyst
bronchogenic cyst
surgery is treatment of choice
thymic cyst
located in th eanterosuperior mediastinum
generally asymptomatic in adults
unilocular if congenital
multilocular if acquired
histology of thymic cysts
inflammation, residual thymic tissue in 50% of cases, degenerative features influding presence of cholesterol clefts
lesions of the mediastinum
chronic fibrosing mediastinitis
infectious granulomas
sarcoidosis
chronic fibrosing mediastinitis
located in the middle/anterior mediastinum
present with chest pain, fever, hemoptysis, SVC syndrome
two important forms are infectious lymphadenitis (due to histoplasma) and IgG type 4 plasma-cell diseases (responds to steroids)
can also be caused by other types of granulomatous disease, including TB
histology of fibrosing mediastinitis
lymphoplasmacytic inflammation and fibroblasts and dense fibrosis are histologic features associated with IgG type 4 lesions
obliterative phlebitis is a common finding
