Ch. 12 - Lymph Node

Question 1

What lymph nodes are good candidates for needling?

Answer 1

Superficially located, >1cm, and unlikely to be reactive (eg young adults/children).

Question 2

What are the limitations of FNA evaluation of lymph nodal pathology?

Answer 2

No architectural or vascular patterning (required for several lymphoma and benign LAD diagnoses), chance for sampling error.

Question 3

What studies are usually required for subclassing lymph node pathology?

Answer 3

Immunophenotyping (flow is better than immunocytochemistry), molecular studies. Be sure to dedicate material for these ancillary studies.

Question 4

Recall (all of!) the normal cellular components of a lymph node.

Answer 4

T-cells, B-cells (incl. centrocytes, centroblasts, immunoblasts), plasma cells, FDCs, IDCs, TBMs, sinus histiocytes, endothelial cells, mast cells & eosinophils.

Question 5

Describe the cytology of normal lymph node.

Answer 5

Dispersed isolated cells, maybe with some intact follicles. Lymphoglandular bodies (fragments of lymphoid cytoplasm).

Question 6

Which benign lymphadenopathies cannot generally be identified by FNA?

Answer 6

Castleman disease, PTGC, Toxoplasma (if lucky, may see organism in histiocytes), HIV lymphadenopathy, dermatopathic lymphadenitis.

Question 7

Describe the cytology of Sarcoidosis

Answer 7

Epithelioid histiocytes, multinucleated giant cells, and a clean background. Note “boomerang/footprint” nuclei.

Question 8

What fungal organisms may be reliably diagnosed on lymph node FNA?

Answer 8

Cryptococcus, histoplasma, coccidioides

Question 9

Describe the cytology of cat scratch disease.

Answer 9

Granulomas, neutrophils, necrosis. Non-specific.

Question 10

Describe the cytology of mycobacterial lymphadenitis.

Answer 10

Granulomas, neutrophils, necrosis. Look for “negative image” organisms as they resist staining.

Question 11

Describe the cytology of Rosai-Dorfman disease.

Answer 11

Small lymphocytes emperipolesed within large histiocytes (S100+, CD68+).

Question 12

Describe the cytology of Kikuchi lymphadenitis.

Answer 12

Necrotic debris, karyorrhexis, and cytoplasmic tingible bodies. No neutrophils! Crescentic histiocytes.

Question 13

Describe the cytology of Infectious mononucleosis.

Answer 13

Increased percentage of immunoblasts and plasmacytoid lymphocytes. Atypical looking.

Question 14

Describe the cytology of classic Hodgkin lymphoma.

Answer 14

Rare scattered Reed-Sternberg cells in a variable inflammatory infiltrate. May be hypocellular (nodular sclerosing). Not ideally diagnosed by FNA…

Question 15

Describe the cytology of NLPHL.

Answer 15

Very hard to diagnose; look for enlarged popcorn cells in a mixed background.

Question 16

Describe the cytology of Follicular lymphoma.

Answer 16

Irregular cleaved centrocytes and large centroblasts. Few to no TBMs. May or may not see follicular aggregates.

Question 17

Describe the cytology of marginal zone lymphoma.

Answer 17

Polymorphous population including monocytoid and lymphoplasmacytic cells. Nearly impossible to diagnose by FNA.

Question 18

Describe the cytology of SLL.

Answer 18

Monomorphous small lymphocytes with soccer-ball chromatin, often smudge cells. May have prolymphocytes and paraimmunoblasts. Trisomy 12 looks wrinkled/atypical.

Question 19

Describe the cytology of Mantle cell lymphoma.

Answer 19

Monomorphous small to intermediate cells with fine chromatin. No blasts. “Pink” eosinophilic histiocytes? Rarely can look blastoid.

Question 20

What is a good rule of thumb for distinguishing small and large cells?

Answer 20

Large cells should have nuclei larger than histiocyte nuclei (but may still be smaller than most epithelial nuclei).

Question 21

Describe the cytology of DLBCL.

Answer 21

Large cells with large nucleoli and lymphoglandular bodies. Few lymphoid aggregates. May have predominant immunoblasts or centroblasts.

Question 22

Name 3-5 subtypes of DLBCL and recall their cytology.

Answer 22

PMBL: Often limited sample due to compartmentalizing fibrosis.
Double-hit: Looks morphologically identical.
THRLBCL: Scarce tumor cells, hard to call.
PEL, Intravascular LBCL.

Question 23

Describe the cytology of Burkitt lymphoma.

Answer 23

Intermediate-sized cells with round nucleoli, scant vacuolated blue cytoplasm, many apoptoses/mitoses and TBMs.

Question 24

Describe the cytology of Plasmablastic lymphoma. Where is it generally found?

Answer 24

Predominant immunoblasts; isolated from oral cavity or other mucosal sites of the immunocompromised.

Question 25

Describe the cytology of PTCL-NOS.

Answer 25

Non-specific; monomorphous small to large lymphocytes with irregular nuclei.

Question 26

Describe the cytology of ALCL.

Answer 26

Intermediate and large cells including hallmark cells (horseshoe, donut, embryoid).

Question 27

By what pattern does ALCL involve lymph nodes? What is the defining molecular change?

Answer 27

Involves LNs in a sinusoidal pattern.

ALK+ cases generally harbor a t(2;5) ALK-NPM fusion.

Question 28

Describe the cytology of MF.

Answer 28

Cerebriform nuclei–but morphology is insufficient for diagnosis. Need immunophenotyping.

Question 29

Describe the cytology of ATLL

Answer 29

Circulating “floret” cell nuclei with deeply basophilic and vacuolated cytoplasm.

Question 30

Describe the cytology of LBL.

Answer 30

Highly cellular with monotonous lymphoblasts (2x normal size), increased mitoses, scant vacuolated cytoplasm. Hand-mirror?

Question 31

Recall the spectrum of morphologies in PTLD.

Answer 31

May range from “polymorphic” (early) to “monomorphic” (late, looks like DLBCL).

Question 32

What lymphoma is known to resemble carcinoma? Why?

Answer 32

ALCL; lack of lymphoglandular bodies, high cell clustering, rare spindling. Can also be EMA+ and drop many lymphoid markers.

Question 33

What should be kept in the differential for LBL and Burkitt lymphomas?

Answer 33

Other SRBCTs (eg rhabdomyosarcoma, Ewing’s, neuroblastoma).

Question 34

Recall the rare histiocytic and dendritic cell neoplasms and the stains that define them.

Answer 34

Histiocytic sarcoma: CD68, CD163
FDCS: CD21, CD23, CD35
LCH: CD1a, Langerin/CD207

Question 35

What challenges do cystically degenerative SQC metastases pose?

Answer 35

They may be necrotic and be mistaken for branchial cleft cysts or EICs.

Question 36

How does nasopharyngeal carcinoma usually present? Describe its cytology.

Answer 36

As an enlarged cervical node. Lymphocytes obscure clusters of malignant EBV+ epithelium.

Question 37

What are the features of seminoma/germinoma?

Answer 37

Dispersed large vacuolated cells with macronucleoli on a tigroid background (proteinaceous fluid). Stains OCT3/4.

Question 38

What sarcomas to tend to involve lymph nodes?

Answer 38

Synovial sarcoma, Kaposi’s sarcoma, FDCS, epithelioid sarcoma, rhabdomyosarcoma, angiosarcoma.

Question 39

How can CHL and ALCL be distinguished?

Answer 39

Immunostaining for PAX5 and CD15. ALK can also help.

Question 40

In general, how is clonality established in a T-cell proliferation?

Answer 40

Look for aberrant immunophenotype, perform PCR studies on TCR loci.