Hemepath Lymph Node Intro Lecture

Question 1

Normal lymph node architecture

Answer 1

Question 2

Germinal center response to antigen

Answer 2

Question 3

Answer 3

Toxoplasma lymphadenitis

Notice the epithelioid histiocytes present in sparse aggregates and infiltrating into the germinal centers.

Question 4

Findings of florid follicular hyperplasia, intrafollicular plasma cells, and increased paracortical plasma cells should make you suspiciuos for. . .

Answer 4

Syphilis

Question 5

Typical look of parafollicular hyperplasia

Answer 5

The small lymphocytes are mostly T cells and the larger, evenly spaced cells are interdigitating dendritic cells

Question 6

Paracortical lymphoid hyperplasia is common in. . .

Answer 6

dermatopathic lymphadenitis

viral lymphadenitis

Kikuchi disease

Question 7

Dermatopathic lymphadenitis

Answer 7

Associated with a rash or other skin disease

Paracortical hyperplasia that often has associated increased Langerhans cells and macrophages containing melanin pigment

Question 8

Answer 8

Acute EBV-mediated mononucleosis

Don’t be fooled into calling this lymphoma!

Think contextually, get an EBV stain.

Question 9

Do reactive immunoblasts stain for CD30 and CD15?

Answer 9

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.

Question 10

Molecular profiling in DLBCL

Answer 10

Question 11

What type of DLBCL gets rituximab as part of standard therapy?

Answer 11

Activated B cell type

Question 12

Hans algorithm

Answer 12

Question 13

Myc staining in DLBCL

Answer 13

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

Question 14

“Double expressor” vs “Double hit” DLBCL

Answer 14

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.

Question 15

Stain panel for a new DLBCL diagnosis

Answer 15

Hans classifiers: CD10, BCL6, MUM1

Double expressor classifiers: MYC, BCL2

Viral infeciton classifiers: EBER ISH
(if immunocompromised, add HHV8 LANA1)

Question 16

Frequency of T cell antigen loss in T cell neoplasms

Answer 16

CD7 > CD5 > CD2 > CD3

Question 17

TRBC1 and TRBC2

Answer 17

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)

Question 18

Ways to interpret cytoplasmic CD3 expression

Answer 18

T-cell precursor (benign or malignant)
Aberant expression in a mature T cell neoplasm
NK-cell neoplasm

Question 19

Brentuximab vedotin

Answer 19

Anti-CD30-conjugated chemotherapy

Approved for all CD30+ T cell lymphomas AND classic Hodgkin lymphomas

For Hodgkin lymphomas, even just by morphology.

Question 20

Anti-light chain antibodies in differentiating acute EBV (mono) from classic Hodgkin lymphoma

Answer 20

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.

Question 21

Ki-67 index is prognostic in. . .

Answer 21

Follicular and mantle cell lymphomas

Question 22

Primary cutaneous marginal zone lymphoma/LPD

Answer 22

Lymphoma in WHO5
LPD in ICC

Very indolent B cell neoplasm

Question 23

Changes in follicular lymphoma classification and grading

Answer 23

Question 24

“Testicular” FL

Answer 24

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

Question 25

Fibrin-associated LBCL

Answer 25

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.

Question 26

Looks like Primary Effusion Lymphoma, but HHV8 is negative!

Answer 26

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.

Question 27

Pyothorax-associated lymphoma

Answer 27

History of TB with pyothorax

Chronic suppurative inflammation

Mass is often present

Question 28

Double Hit classifications

Answer 28

Question 29

Primary diffuse large B cell lymphomas of immune privileged sites

Answer 29

Question 30

Naming for general lymphoproliferative disorders

Answer 30

Histologic Dx, Virus-association, Type of immunodeficiency if any

ex:
DLBCL, EBV+, post-transplant
DLBCL, EBV+, HIV-associated

Question 31

Plasma cell-associated paraneoplastic syndromes

Answer 31

Question 32

Answer 32

Indolent NK-cell lymphoproliferative disorder of the GI tract

Cells are immunophenotypically perfect for activated cytotoxic NK cells and show prominent perinuclear red granules

Question 33

Nodal TfH lymphomas

Answer 33