Pathology of Lymphomas Flashcards
Tumor grade in lymphoma
Matters more in lymphomas than for some other malignancies
- lymphomas are essentially metastatic in nature
- treatment is very heavily dependent upon chemo and radiation –> not amenable to surgery
- high grade tumors are more susceptible to treatment
- –> replicate very quickly - cell division is a vulnerable time and drugs are most effective
- –> often diverge more from normal cells - have a better chance of killing the tumor cells and not healthy cells
- if treatment fails, usually a poor prognosis
Tumor stage in lymphoma
Stage 1 = single location
Stage 2 = multiple sites, same side of the diaphragm
Stage 3 = multiple sites, both sides of the diaphragm
Stage 4 = diffuse involvement of non-lymphoid organs
Tumor staging techniques
- Biopsy/resection methods
- needed to establish diagnosis
- differential may include other malignancies or inflammatory conditions - Radiology
- Clinical findings
- Blood
- CSF
Hodgkin Lymphoma
Neoplastic proliferation of Reed Sternberg cells = large B cells with multilobed nuclei + prominent nucleoli (owl eyed nuclei) –> positive for CD15 + CD30
RS cells secrete cytokines
- occasionally results in B symptoms = night sweats, fevers, chills, weight loss
- attract reactive lymphocytes, plasma cells, macrophages and eosinophils
- may lead to fibrosis
Reactive inflammatory cells make up a bulk of the tumor and form the basis for classification of HL
Less often widely disseminated as compared to Non-Hodgkins lymphomas –> pattern of spread closer to carcinoma (travels to adjacent areas)
Hodgkin Lymphoma - Morphology
Reed Sternberg cells = minority of cells
- mostly germinal center or post-germinal center B cells
- big, prominent nuclei + nucleolus (owl eye)
- lots of cytoplasm
Reactive infiltrate = majority of cells
- lymphocytes, plasma cells, eosinophils, etc –> often predominates
- limits the utility of flow cytometry/molecular studies
Hodgkin Lymphoma - Subtypes
Classical = regular RS cells
- different subtypes within this category
- CD15+/CD30+
- EBV + often –> depends on subtype
- prognosis depends on subtype
Non-classical = popcorn RS cell
- lymphocyte predominant subtype
- CD15-, CD30-, EBV-
- prognosis generally good
Subtypes of classical Hodgkins Lymphoma
- Nodular sclerosing = most common
- classic presentation is an enlarging cervical or mediastinal lymph node in a young adult, usually female
- lymph node is divided by bands of sclerosis
- RS cells are present in lake like spaces = lacunar cells
- rare EBV association - Lymphocyte rich = EBV+ 40% of time
- best prognosis of all types - Mixed cellularity = EBV + 70% of time
- Often associated with abundant eosinophils –> RS cells produce IL-5 - Lymphocyte depleted = EBV 90% of time
- most aggressive of all the types
- seen in elderly and HIV positive patients
*Generally, as ratio of RS:lymphocytes increases = rate of EBV+ increases and prognosis decreases
Hodgkins vs. Non-Hodgkins
Localization
- Hodgkins = localized
- NHL = disseminated/diffuse
Spread
- Hodgkins = contiguous
- NHL = non-continguous
Extranodal presentation
- Hodgkins = rare
- NHL = common
B symptoms
- Hodgkins = marked
- NHL = usually mild/absent
Diffuse Large B Cell Lymphoma
Neoplastic proliferation of large B cells (CD20+) that grow diffusely in sheets
- most common form of NHL
- Clinically aggressive = high grade
Arises sporadically or from transformation of a low grade lymphoma (eg follicular lymphoma)
Presents in late adulthood as an enlarging lymph node of an extranodal mass –> can arise anywhere in the body
DLBCL - Morphology
- diffuse pattern of growth
- large cells ~5x normal lymphocyte diameter
- may be hard to correctly identify
- –> may resemble hodgkins
- –> may resemble non-lymphomatous malignancy
DLBCL - Immuno and Molecular
Express mature B cell immunomarkers
- flow cytometry may not be useful –> cells die quickly
Heterogeneous molecular abnormalities
- BCL6
- t(14:18) (Bcl2)
- ** these mutations are mutually exclusive
- may derive from several different unidentified precursor lesions with DLBCL as a common morphologic endpoint
DLBCL - Viral associated subtypes
Immunodeficiency-associated
- HIV/bone marrow transplant
- EBV driven
Primary effusion lymphoma = occupies pleural space between chest wall and lung
- HHV8 association
- don’t express B or T cell markers = hard to recognize –> IgH gene arrangement
Burkitt Lymphoma
Neoplastic proliferation of intermediate sized B cells (CD20+)
- associated with EBV
- classically presents as an extranodal mass in a young adult or child
3 major epidemiologic types
- Endemic (African) - practically all EBV
- –> usually involves jaw - Sporadic form - minority EBV
- –> usually involves the abdomen - HIV-minority EBV
* **subtypes are histologically identical but the clinical picture differs
Burkitt Lymphoma - Morphology
- medium sized cells with moderate cytoplasm
- high rate of apoptosis –> macrophages with dead cells = “starry sky”
- extremely high rate of mitosis –> virtually all cells are in cycle (Ki67 ~100%)
- often presents as a rapidly growing on mass –> depending on location may be an emergency
Burkitt Lymphoma - Immuno and Molecular
Mature B cells –> usually not Bcl2
High rate of mitosis –> extremely high Ki67
All forms have c-MYC translocation (chromosome 8)
- over expression of c-myc oncogene promotes cell growth
- t(8;14) = most common –> translocation of c-myc to the IgH locus on chrom 14
- t(2;8) = Ig kappa
- t(8;22) - Ig lambda
Follicular lymphoma
Neoplastic proliferation of small B cells (CD20+) that form follicle like nodule
- germinal center B cells
- presents in late adulthood with painless lymphadenopathy
- may transform to more aggressive lymphoma
Driven by t(14;18)
- BCL2 on chromosome 18 translocates to the IgH locus on chromosome 14 –> results in overexpression of Bcl2 = inhibits apoptosis
Follicular lymphoma - morphology
- lymph nodes, spleen, marrow, liver
- nodular aggregates of cells (resemble follicles)
- cells
- –> centrocytes = small cells, irregular nuclear contours and little cytoplasm (usually majority)
- –> centroblasts = bigger cells with nucleoli and more cytopasm