Lymphadenitides

Question 1

Answer 1

Toxoplasma lymphadenitis

Characterized by follicular hyperplasia (FH) and not paracortical hyperplasia. In addition to FH the presence of epithelioid histiocytes impinging on germinal centers and presence of monocytoid lymphocytes (often present near sinusoids) are additional characteristic features of toxoplasma lymphadenitis.

Question 1

Answer 1

Dermatopathic lymphadenitis

Characterized by nodular paracortical hyperplasia.

In addition to T cells, there are increased Langerhans/interdigitating dendritic cells admixed with melanin-laden macrophages. The interdigitating dendritic cells have elongated, twisted nuclei with nuclear grooves, pale chromatin, inconspicuous nucleoli, and abundant eosinophilic cytoplasm.

Question 2

Answer 2

Infectious mononucleosis (IM) lymphadenitis

Characterized predominantly by paracortical hyperplasia. Due to the polymorphous composition, the paracortex often has a “moth-eaten” appearance.

Question 3

T-cell non-Hodgkin lymphoma-associated lymphadenitis

Answer 3

Many T-cell non-Hodgkin lymphomas (NHLs) can be characterized by paracortical expansion; however, unlike dermatopathic lymphadenopathy and infectious mononucleosis, the overall lymph node architecture is disturbed with sinuses showing obliteration and follicles being atrophic and marginalized.

Question 4

Types of lymphoid hyperplasia

Answer 4

1. Follicular
2. Immunoblastic/Infectious mononucleosis-like/Partacortical
3. Plasma cell

Question 5

Answer 5

Follicular hyperplasia

Question 6

Answer 6

Immunoblastic hyperplasia / Paracortical hyperplasia

Question 7

Answer 7

Plasma cell hyperplasia

Question 8

Polymorphic lymphoproliferative disorders

Answer 8

Destructive hematolymphoid proliferations composed of heterogeneous populations of cells. Unlike hyperplastic lesions, these lesions disrupt tissue architecture. However, they do not meet diagnostic criteria of lymphoma.

Recognized by their B-cell component, which shows a range of differentiation along the mature B-cell spectrum:
Lymphocytes, Immunoblasts, and Plasma cells

Question 9

Answer 9

Progressive transformation of germinal centers

Slow replacement of follicles by enchroaching mantle cells from the edge.

Question 10

If you’re not sure whether or not there is a mantle, what is the best stain to tell you?

Answer 10

IgD

Question 11

In young kids, you can sometimes see ___ within follicle mantles.

Answer 11

CD5+ WT B cells

Question 12

Monocytoid B cells

Answer 12

Most prominent in certain types of lymphadenitis, in particular CMV and toxoplasma

Oval or bean-shaped nuclei, lots of cytoplasm

Question 13

Lipogranulomas tell you that a lymph node is from the. . .

Answer 13

. . . portal system!

Question 14

ALK+ DLBCL likes to go to. . .

Answer 14

. . . lymph node sinuses!

Like a carcinoma. ALK can bring these out if you are struggling.

Question 15

AITCL and the sinus

Answer 15

AITCL likes to invade into the capsule and perinodal fat, but spares the subcapsular sinus, which will be patent.

Question 16

If you want to find HSV nuclear changes in HSV lymphadenitis, you have to look. . .

Answer 16

. . . in the necrotic debris.

Question 17

Pediatric type nodal follicular lymphoma looks a LOT like. . .

Answer 17

Burkitt, in terms of the cytology.

But, unlike Burkitt . . . it is cured by simple excision.

This is a HUGELY important differential to get right.

Question 18

HHV8+ lymphomas can display. . .

Answer 18

. . . aberrant expression of T cell antigens, like CD3

Primary Effusion Lymphoma can also look a lot like ALCL.