Mediastinum Flashcards
Large mass of tissue positioned between the pleurae of the lungs
Mediastinum
Includes almost all components of the thoracic cavity except the —?
lungs
above this line => superior & anything below => inferior
Plane of Ludwig
Mediastinum is subdivided into 4 sections by the —?
Pericardium
what are the 4 subsections of mediastinum?
Superior, anterior, middle & posterior
Specialized lymphoid organ in the mediastinum, located between the lungs
Thymus
What does Thymus produces to stimulate development of of T lyc?
Thymosin
Why is cortex darker than the medulla on histology?
More lyc are in cortex than in medulla - lighter stained
Referred to as “military specialists” & are made in bone marrow as pre-cursors then gets released into peripheral blood
T cells
Only active until puberty where it undergoes atrophy
Thymus
what kind of cells can be found in medulla & forms forms pearls on histology on Thymus?
Reticular Cells
Epithelial cells are connected to each other by —– and the intermediate filament protein keratin is present in their cytoplasm.
Desmosomes
One of the small bodies of the medulla of the thymus having granular cells at the center surrounded by concentric layers of modified epithelial cells
Hassall’s corpuscles: Pearls
Lymphoma most commonly arises in which part of Mediastinum?
Anterior
4 Ts of Mediastinum
Thymoma: Tumor of thymic cells
Thymic Carcinoma
T-Cell (Terrible) Lymphoma has worse prognosis
Teratoma/Germ Cell Tumors: squamous cells
Dispersed lymphocytes with tight clusters of epithelial cells
Bland with no nucleoli
Spindle cell variant has elongated epithelial cells
Abundant cytoplasm
Also linked to Myasthenia Gravis (MG)
Thymoma
What are the different subtypes of Thymoma & which is malignant?
A, AB, B1, B2, B3, C
C is highly malignant
What are the two morphologies of a Thymoma?
Spindle cells or epithelioid cells
What are some markers used for Thymoma?
TdT (T cells)
CD99 (lymphocytes)
Keratin
P63
Name 3 differentials for a Thymoma
Lymphoma, seminoma, NSLC
Children/teenagers
Monoclonal population of cleaved or non-cleaved lymphoblasts
CD3+
T cell Lymphoma
Which lymphoma has a good prognosis & high cure rate?
HL
Adrenal gland; most common pediatric tumor
Neuroblastoma
Where do these tumors develop in mediastinum:
Neuroblastoma (pediatric tumor)
Ganglioneuroma
Schwannoma
Chordoma (tumor from spinal cord)
Metastatic Tumors
Posterior Mediastinum
Children
Also occurs in adrenal gland
Benign
Spindle cells
Large round pleomorphic cells (ganglion cells)
Granular cytoplasm
IHC- S-100, NSE
Benign
Ganglioneuroma
Neoplasm arising form Schwann cells
Well circumscribed masses attached to peripheral nerves, cranial nerves or nerve roots
Comprised of densely packed spindle cells
Palisading nuclei (Verocay bodies, Antoni A)
Intermixed with looser myxoid areas
Schwannoma
Almost always benign
2 areas: Antoni A & Antoni B
Can occur anywhere in body but mainly in central part of body => mediastinum
Spindle cell neoplasm
Histology: Skin example
Schwannoma
Areas are characterized by densely packed spindle-shaped Schwann cells arranged in a palisading pattern. Verocay bodies, which are alternating bands of cellular and acellular areas, may be present. Antoni A areas tend to be more cellular and organized. “Cellular”
Antoni A
Areas are less organized and have a looser, myxoid, or cystic appearance. Schwann cells are less densely packed, and there may be areas of degeneration, hemorrhage, or cyst formation. “Cystic”
Antoni B
Which marker will test (+) for Schwannoma?
S100
Spindle cells with bent wavy nuclei
Associated with dense fibrous stroma
Rare to absent cytologic atypia
May be cystic
IHC- S-100, EMA, CD68, GFAP
Schwannomas
-Where spine diffuses top of spine or bottom of spine
-Multiple lobulated
-Myxoid background: epithelial cells (islands); cytoplasm can be eosinophilic; cells have “bubbles” in them => physaliferous cells => multiple vacuolations
Keratin & S100 makers
Chains or islands
Chordoma
