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MEDIASTINAL SYNDROMEDr Tai Al AkawyPediatrician and neonatologistAlexandria University Childrens Hospital
Compression of mediastinal structures by any mass gives rise to a group of symptoms known as mediastinal syndrome
Mediastinal masses affect patients at any age and can be asymptomatic
33% of all masses present in patients less than 15 years oldIf small, usually asymptomatic and found incidentally If large, usually present with respiratory distress
The mediastinum is the region in the chest between the pleural cavities that contain the heart and other thoracic viscera except the lungsBoundaries Anterior- sternumPosterior - vertebral column and paravertebral fasciaSuperior -thoracic inletInferior- diaphragmLateral - parietal pleura
Sternal AngleThoracic inletThoracic ouletBoundaries of mediastinumsternumThoracic vertebra
TS: Mediastinum*CS: Mediastinum
ANATOMY OF MEDIASTINUMIt is the anatomic space that lies in the midthorax It is limited by the diaphragm below and the suprasternal thoracic inlet above. It contains several vital structures in a small space,Abnormalities can produce important symptoms.
Contents of the mediastinumThe Anterior compartment contains The ThymusSubsternal extensions of the thyroid Parathyroid glands blood vesselsPericardiumLymph nodes
Contents of the mediastinumThe middle compartment contains the Heart, Great vessels,Trachea, Main bronchi, Lymph nodes, Phrenic and Vagus nerves.
Contents of the mediastinum The posterior compartmentThe vertebrae Descending aortaOesophagusThoracic ductAzygous and Hemizygous veins Lower portion of the vagusSympathetic chains, andPosterior mediastinal nodes.
Anterior Mediastinal Masses: (4 T's) (30% of mediastinal masses)
Thymoma Teratoma Thyroid (Ectopic) (Terrible) Lymphoma
Thymomalobulated mass in the anterior mediastinum
Thymoma Located in superior and / or anterior mediastinum. Can occur in all age groups but mostly seen in in adults80 % have symptoms of myasthenia gravis
Differential diagnosis : Reactive lymphoid hyperplasia Cytological distinction between thymus and thymoma is difficult. Follicular lymphoma Precursor T lymphoblastic lymphoma
Hilum can be seen through massthis must be an anterior mediastinal mass because it overlaps rather than pushes out the main pulmonary arteries
This particular example is a thymoma
The CT-images shows a large soft tissue mass in the anterior mediastinum, which arises in the thymus. There is associated paratracheal adenopathy (arrow).
(a) PA chest radiograph demonstrates a goiter (arrow) extending into the middle mediastinum, causing deviation of the trachea to the left (black arrowhead). Right-sided retrosternal goiter
(b) CT scan shows the mass (arrow) between the trachea and right lung
LymphomaLymphoma is the most common cause of an anterior mediastinal mass in children and the second most common cause of an anterior mediastinal mass in adults.
Lymphomas Primary mediastinal large B cell lymphomaPrecursor T lymphoblastic lymphoma/leukemiaAnaplastic large T cell lymphoma , mature T cell lymphoma. Hodgkins lymphoma.
In this case, enlarged lymph nodes are seen in the right paratracheal , hilar and subcarinal areas without thymus involvement
Anterior mediastinal teratoma - A large heterogenous left anterior mediastinal mass containing soft tissue , fatty and calcific components.Germ Cell Tumour
Germ cell tumors Seminoma Embryonal carcinoma Yolk sac tumors Choriocarcinoma Teratoma ; mature Teratoma; immature
Teratoma Most common mediastinal germ cell tumor ( 50-70 % )Mature teratoma : adult type tissue Immature teratoma: immature embryonal type of tissue; Mostly benign; Mixture of somatic tissue of 3 germ layers ; ectoderm, endoderm, mesoderm. Immature teratoma : biphasic cell pattern ; loose aggregates of small round cells in fibrillary matrix represents neuronal component. Malignant transformation can occur : MC is SCC or adenocarcinoma.
Mature teratoma shows : squamous epithelium, hair shaft, respiratory epithelium, chondromyxoid stroma which is better demonstrated with diff stick ( MGG ) stain- Metachromatic colour. *
Embryonal carcinoma Rare type of non seminomatous germ cell tumor in young males. Often associated with teratoma ( teratocarcinoma ), Choriocarcinoma, or seminoma. Cytologically embryonal carcinoma is indistinguishable from poorly differentiated carcinoma of non germ cell origin. Mitotically active tumor with malignant cells arranged in poorly cohesive 3 D clusters , with syncitial growth pattern. Occur either as mixed or pure form. AFP levels are elevated in all cases.
Yolk sac tumor / endodermal sinus tumor Rare mediastinal tumor can occur both in paediatric ( female predilection ) as well as in adults ( male predilection ).Commonly associated with elevated AFP levels. Coagulative tumor necrosis is abundant Schiller- Duval bodies/ Glomeruloid bodies diagnostic are seldom seen. Identification of eosinophilic basal lamina like substances and intra-cytoplasmic hyaline globules ( PAS + & diastase resistant), give clue to diagnosis.
S-D bodies are formedd due to invagination of tumor cells and capillaries in to cystic space. *
Choriocarcinoma Pure medastinal choriocarcinoma is extremely rare virtualy non existent in children. Highly aggresive tumor. Elevated S. HCG level. Mixture of syncytiotrophoblasts and cystotrophoblasts against haemorrhagic background. Syncytiotrophoblastic giant cells with eosinophilic cytoplasm , pleomorphic nuclei, prominent nucleoli,Cytotrophoblasts are medium sized cells with vaculated basophilic cytoplasm.
Haematogenous spread , pt present with features of gynacomastia. Practically speaking the ability of FNAC in separating various non semonomatous germ cell tumors, specially between embryonal carcinoma, yolk sac tumor, and choriocarcinoma are rather limited. There is often morphological overlap and its not uncommon to find mixture of various germ cell tumor components with in single lesion. *
. Middle Mediastinal masses
Middle Mediastinal Masses (30% of mediastinal masses) Adenopathy :
infection [bacterial, granulomatous] neoplasm [leukemia / lymphoma, metastases]Bronchopulmonary or foregut malformations: Esophageal duplication cyst,
Bronchogenic cyst, Sequestration
MEDIASTINAL LYMPHADENOPATHYMiddle mediastinum is the commonest site of intrathoracic lymphadenopathy.Gross lymphadenopathy is a feature of
1)Tuberculosis 2)Histoplasmosis 3) Metastatic malignancy 4) Lymphomas 5)Sarcoidosis
Foregut cysts in the middle mediastinum are classified as bronchogenic or enteric. Bronchogenic cysts are lined by respiratory epithelium and most are located in the subcarinal or right paratracheal area Enteric cysts are lined by gastrointestinal mucosa and are located in the middle or posterior mediastinum near the esophagus
(Right) AP radiograph shows large, smooth, homogeneous, left retrocardiac parenchymal mass (arrows).(Left) Axial T2 MRI shows homogeneous, well circumscribed ovoid mass (arrow) with signal greater than CSF (curved arrow).BRONCHOGENIC CYST
Enteric foregut cystThe images show a well defined lesion in the lower mediastinum in close proximity to the esophagus, which is typical for an enteric foregut cyst.
Posterior Mediastinal masses
There are 4 histological types.1.NEURILEMMOMA Benign and is classically a dumbbell-shaped mass. compress the spinal cord and produce pressure symptoms.
2.GANGLIONEUROMABenign, elongated and large. Usually occurs in children but may be found at any age. Causes flushing,hypertension,headache,sweating,diarrhoea.3.NEUROFIBROMAAssociated with generalized neurofibromatosis (von Recklinghausen's disease).
4.NEUROBLASTOMA Malignant and found frequently in children.
The CT-images show a calcified mass in the posterior mediastinum extending over several vertebrae, which grows into the vertebral canal.Neuroblastoma
See sharp margin above clavicle
Mass is in posterior mediastinum, because it remains sharply outlined in apex of thorax, indicating that it is surrounded by lung.This particular example is a ganglioneuroma
An approach to mediastinal syndrome and masses
Epithelial tumors ThymomaThymic carcinoma Germ cell tumors Pure GCTs : GCTs with only one histological typeMixed GCT : GCT with more than one histological type GCTs with somatic type malignancy GCTs with associated malignancy
WHO Classification of thymic tumors and mediastinal tumors
Mediastinal lymphomas and haematopoietic neoplasms: B-cell lymphomaT-cell lymphoma Hodgkins lymphoma Histiocytic and dendritic cell tumors Myeloid sarcoma and extra-medullary acute myeloid leukaemia Mesenchymal tumors of mediastinum: Thymolipoma Lipoma of mediastinum Liposarcoma of mediastimum Solitary fibrous tumors Synovial sarcomas
Vascular neoplasms Rhabdomyosrcoma Leiomyomatous tumors Peripheral nerve sheeth tumors Ectopic tumors of mediastinum Ectopic tumors of thymus Ectopic tumors of thyroid Ectopic tumors of parathyroid Metastasis to thymus and to anterior mediastinum