Primary Mediastinal B Cell Lymphoma Flashcards Preview

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Flashcards in Primary Mediastinal B Cell Lymphoma Deck (19):

From which cells does Primary Mediastinal B Cell LYmphoma arise from?

Thymic (Medullary) B cells

Has features distinct from DLBCL
Shares some clinical + Biologic features with classical Nodular sclerosing Hodgkin Lymphoma


How frequent is PMBL?

7% of DLBCL
2.4% of all NHL


What is the epidemiology of PMBL?

7% of DLBCL
2.4% of all NHL
Median age 30-40 yo


What are some features of SVCO?

Usually a/w the compression/invasion of the structures around.
- Trachea - airway compromise
- Heart - pericardial effusion/tamponade
- lungs/pleura - SOB/cough/dyspnoea/pleural effusion
- blood vessels - SVCO

Frequently with airway compromise
Facial swelling/head fullness exacerbated by bending forward or lying down
Arm swelling
Chest pain


What are the potential oncological emergencies that can occur with PMBL?

Acute airway obstruction
Pericardial tamponade
Hyperuricemia and TLS
Thrombosis of major neck/superior thoracic veins


What is tumor lysis syndrome?

Oncological emergency that is caused by massive tumor cell lysis and the release of large amounts of potassium, phosphate and Uric acid into the systemic circulation.

THe deposition of Uric acid and/or Ca Phosphate crystals in the renal tubules can cause ARF (which is usu anuric)


What is the morphology in PMBL?

Large cells with variable nuclear features resembling centroblasts, large centrocytes or multilobulated cells, often with pale/clear cytoplasm.
Sometimes resemble immuoblasts.

RS cells may be present
Many with fine, compartmentalizing sclerosis


What is the immunophenotype of PMBL?

Can be confirmed by histo chemistry or flow cytometry.

Express B-cell-associated Ag: CD19, CD20, CD22, CD79a, CD45
CD5- CD10- CD15-
CD30 Weakly +
TRAF-1+, c-Rel+
Typically do NOT express immunoglobulins.
B Cell transcription factors: PAX5, OCT2, BOB1 strongly expressed
Germinal center markers usually expressed CD10+ BCL6+ CD23+


How can biopsies of PMBL be obtained by?

Cervical Mediastinoscopy
Anterior mediastinotomy


What are the differential diagnosis for PMBL?

Benign mediastinal tumors
Malignant mediastinal tumors
- Systemic lymphoma with secondary mediastinal involvement
- Hodgkin Lymphoma
Infectious entity (eg. Histoplasmosis)
Inflammatory entity


How do you differentiate DLBCL from PMBL?

PMBLs typically express:
- CD30 + (weak)
- TRAF-1
- nuclear c-Rel


How do you differentiate Hodgkin Lymphoma and PMBL?

Via immunophenotyping.
- classical HL:
>>> CD15+ (85% of cases);
>>> high levels of CD30 (>95% of cases);
>>> lack of pan-B and pan-T cell antigens
>>> express pan-B cell Ag
>>> weak expression of CD30
>>> rarely express CD15


What is common between HL and PMBL?

Both more common in young women
Both not uncommonly present with large mediastinal mass
On biopsy, PMBL may have cells that resemble RS-cells
Some gene expression profiling similarity


What is a gray zone lymphoma?

Gray-zone lymphoma = B cell lymphoma, unclassifiable
- with features intermediate btwn DLBCL and cHL


What can you comment about the choice of therapy for PMBL?

Optimal treatment of PMBL is unknown with variation in clinical practice.

When possible, clinical trial is an option.
Outside of a clinical trial, tx options depend on patient, tumor characteristics ad physician comfort.

All patients are treated with induction Chemoimmunotherapy.
Use of RT as part of primary treatment is more controversial and depends on the choice of induction Chemoimmunotherapy and whether disease is present outside of the chest.

Choice of treatment also depend if PMBL is limited stage or advanced stage disease.
- limited stage meaning disease can be contained within one irradiation field
- advanced refers to disease that cannot be contained within one RT field; bulky; associated pericardial/pleural effusions


What are the options in limited stage PMBL?

1) 6# RCHOP --> IFRT
2) 6#-8# DA-REPOCH (without RT)


What are the options in advanced stage PMBL?

1) 8#RCHOP --> IFRT
2) 6-8# DA-REPOCH (Without RT)


What are the potential long-term complications with RT

Accelerated ATH Cardiac disease
Lung cancer
Breast cancer


How about comments with regards to 2nd line therapy in PMBL?

No standard or agreed upon best therapy with relapsed/refractory PMBL

Relapsed and refractory disease can be suggested by radiological changes but confirmed only by biopsy.
A biopsy should always be used to document relapsed/refractory disease before proceeding to salvage Therapy.

General approach is systemic chemo +/- Rituximab --> HDChemotherapy --> HCT