Hemepath Lymph Node Intro Lecture Flashcards
Normal lymph node architecture
Germinal center response to antigen
Toxoplasma lymphadenitis
Notice the epithelioid histiocytes present in sparse aggregates and infiltrating into the germinal centers.
Findings of florid follicular hyperplasia, intrafollicular plasma cells, and increased paracortical plasma cells should make you suspiciuos for. . .
Syphilis
Typical look of parafollicular hyperplasia
The small lymphocytes are mostly T cells and the larger, evenly spaced cells are interdigitating dendritic cells
Paracortical lymphoid hyperplasia is common in. . .
dermatopathic lymphadenitis
viral lymphadenitis
Kikuchi disease
Dermatopathic lymphadenitis
Associated with a rash or other skin disease
Paracortical hyperplasia that often has associated increased Langerhans cells and macrophages containing melanin pigment
Acute EBV-mediated mononucleosis
Don’t be fooled into calling this lymphoma!
Think contextually, get an EBV stain.
Do reactive immunoblasts stain for CD30 and CD15?
They may stain for CD30, however they should NOT stain for CD15.
Thus, CD15 positivity argues for a Hodgkin lymphoma over a Hodgkinoid immunoblastic proliferation.
Molecular profiling in DLBCL
What type of DLBCL gets rituximab as part of standard therapy?
Activated B cell type
Hans algorithm
Myc staining in DLBCL
Very non-specific for the myc rearrangement – you HAVE to use FISH to detect this.
However, myc IHC is often still done as part of characterizing “double expressor lymphomas.” If a DLBCL expresses both myc >40% and BCL2 >50% by IHC, the prognosis is worse than a non-double expressor DLBCL
“Double expressor” vs “Double hit” DLBCL
Double expressor = By IHC, >40% myc positive and >50% BCL2 positive. Worse prognosis than non-DE, better prognosis than double hit.
Double hit = By FISH, IGH::MYC and IGH-BCL2 rearranged. Worst prognosis.
Stain panel for a new DLBCL diagnosis
Hans classifiers: CD10, BCL6, MUM1
Double expressor classifiers: MYC, BCL2
Viral infeciton classifiers: EBER ISH
(if immunocompromised, add HHV8 LANA1)
Frequency of T cell antigen loss in T cell neoplasms
CD7 > CD5 > CD2 > CD3
TRBC1 and TRBC2
Uniform expression shows clonality in T cells, similar to kappa and lambda in B cells
Two chains of the T cell beta receptor (for alpha-beta TCRs)
Ways to interpret cytoplasmic CD3 expression
T-cell precursor (benign or malignant)
Aberant expression in a mature T cell neoplasm
NK-cell neoplasm
Brentuximab vedotin
Anti-CD30-conjugated chemotherapy
Approved for all CD30+ T cell lymphomas AND classic Hodgkin lymphomas
For Hodgkin lymphomas, even just by morphology.
Anti-light chain antibodies in differentiating acute EBV (mono) from classic Hodgkin lymphoma
Immunoblasts typically have some surface light chain expression by IHC.
If you perform anti-kappa and anti-lambda stains, you can demonstrate that the immunoblasts in mononucleosis are in fact polytypic, ruling out Hodgkin lymphoma.
Ki-67 index is prognostic in. . .
Follicular and mantle cell lymphomas
Primary cutaneous marginal zone lymphoma/LPD
Lymphoma in WHO5
LPD in ICC
Very indolent B cell neoplasm
Changes in follicular lymphoma classification and grading
“Testicular” FL
Dropped from WHO5 because it is so vanishingly rare and is not clear that it is distinct from pediatric-type FL
Still in the ICC
Fibrin-associated LBCL
Do not create a mass, localized, does not invade into tissue, and may be related to local immune escape shielding EBV+ B cells from immune surveillance.
MUCH better prognosis than the rest of DLBCL-CI, hence it is now described as its own entity in WHO5.
Looks like Primary Effusion Lymphoma, but HHV8 is negative!
Fluid overload-associated large B cell lymphomas in WHO5
HHV8 negative primary effusion lymphoma in ICC
Generally arise in older people with underlying medical problems who have a reason to have an effusion, with the B cell neoplasm seeming to arise secondary to the effusion. In contrast, in HHV8-associated PEL, HHV8 creates the fluid collection.
HHV8 MUST be negative.
Most lack specific immunodeficiency. More likely to involve multiple cavities than PEL. 30% of cases have HBV, which is highly associated with peritoneal involvement.
A subset of these patients go into remission after simple drainage of the fluid alone.
Pyothorax-associated lymphoma
History of TB with pyothorax
Chronic suppurative inflammation
Mass is often present
Double Hit classifications
Primary diffuse large B cell lymphomas of immune privileged sites
Naming for general lymphoproliferative disorders
Histologic Dx, Virus-association, Type of immunodeficiency if any
ex:
DLBCL, EBV+, post-transplant
DLBCL, EBV+, HIV-associated
Plasma cell-associated paraneoplastic syndromes
Indolent NK-cell lymphoproliferative disorder of the GI tract
Cells are immunophenotypically perfect for activated cytotoxic NK cells and show prominent perinuclear red granules
Nodal TfH lymphomas
