Reactive lymph nodes

Question 1

Benign process that can extend into perinodal tissue

Answer 1

Infectious mononucleosis

Question 2

Scientific name of syphilis

Answer 2

Treponema pallidum

Question 3

Toxoplasma triad

Answer 3

Follicular hyperplasia
Sinusoidal monocytoid B cells
Epithelioid histiocyte aggs in mantle zone

Question 4

Cat scratch disease clinical features

Answer 4

Bartonella henselae
Inocculation site - erythematous papule, lymphadenopathy of draining nodes
Fever, malaise

Question 5

Cat scratch disease microscopic features

Answer 5

Capsulitis
Follicular hyperplasia
Germinal centre abscesses with palisaded granuloma surrounding
Endothelial cell swelling with organisms within, seen on Warthin Starry stain

Question 6

Differentials of LNs with granulomatous abscesses

Answer 6

Lymphogranuloma venereum (Chlamydia trachomatis)
Tularemia - arthropods
Kikuchi-Fujimoto (histiocytic necrotising lymphadenitis)
TB/BCG
Yersinia
Pseudemonas mallei
Crohn's
Schistosomiasis
Leishmaniasis
Lepromatous leprosy (ZN stain +ve)
Mycobacterium avium intracellulare
Histoplasmosis

Question 7

CMV lymphadenitis histological features

Answer 7

Follicular hyperplasia
Monocytoid B cell hyperplasia
Infected cells with red nucleus, look like RS cell and CD15 +ve but also CMV +ve (immuno and FISH)
Histiocytes and neutrophils
Endothelial cells also infected

Question 8

Kikuchi-Fujimoto clinical features

Answer 8

Tender unilateral cervical lymphadenopathy

Fever, rash, anaemia

Question 9

Kikuchi-Fujimoto pathological features

Answer 9

Karryorectic debris and eosinophilic material, surrounded by histiocytes and immunoblasts
FEW neutrophils, no granulomas
Small lymphcytes surrounding necrosis are CD8+ve T cells, may express CD30
Can partially involve node (unlike lymphomas)

Question 10

Differentials of Kikuchi-Fujimoto

Answer 10

NHL e.g. DLBCL

Lupus lymphadenitis - Can look exactly the same + Azzapardi phenomenon, haematoxylin bodies

Question 11

Herpes simplex virus histology

Answer 11

Paracortical hyperplasia
Necrotic areas containing cells with intranuclear inclusions
Histiocytes but no granulomas
Immuno, ISH, culture

Question 12

Plasma cell variant Castleman’s histologic features

Answer 12

Interfollicular expansion by plasma cells
A few hyaline vascular-type follicles or hyperplastic follicles
Plasma cells may express monotypic Ig, usu IgG or IgA lambda
Always do HHV-8

Question 13

DDX plasma cell variant Castleman’s

Answer 13

Autoimmune diseases (RA, lupus)
Plasmacytoma
Lymphoplasmacytic lymphoma
Always do HHV-8

Question 14

DDX hyaline vascular Castleman’s

Answer 14

Mantle cell lymphoma

Follicular lymphoma

Question 15

Mast cell disease clinical associations

Answer 15

Cutaneous mastocytosis
Systemic mastocytosis
Mast cell leukaemia, sarcoma
Associated with other haematological diseases

Question 16

Mast cell disease histopathology

Answer 16

Medullary cords and paracortex
Spindle cells, binucleate
Can look like plasma cells on H+E, or clear cytoplasm
Mast cells CD117, CD2, mast cell tryptase, CD68 +ve
Romanovsky stains: Wright, Giemsa
Metachromatic stains: Toledine blue, ZN

Question 17

Rosai-Dorfman clinical associations

Answer 17

Monoclonal hypergammaglobulinaemia, raised ESR
Cervical lymphadenopathy, also skin, lungs, bone
Haemolytic anaemia
Localised disease benign
Systemic disease poor prognosis

Question 18

Rosai Dorfman histology

Answer 18

Massive sinus histiocytosis
Emperipolesis
Plasma cells in medulla
Immuno: S100+ve, CD68 +ve, CD1a -ve

Question 19

Rosai Dorfman differentials

Answer 19

Sinus histiocytosis
Mycobacteria esp MAI in immunocompromised
Langerhans cell histiocytosis
Metastasis
ALCL

Question 20

Langerhans cell histiocytosis histopathology

Answer 20

Langerhans cells
Eosinophils
Plasma cells
Fibrosis
Immuno: CD1a, S100, CD45, weak CD68 +ve. CK, vimentin -ve
Birbeck granules diagnostic

Question 21

LCH clinical

Answer 21

3 forms:
Eosinophilic granuloma
Systemic
Hand-Schuller-Christian (diabetes insipidus, lytic skull lesions)
Treated with surgery, radiation, chemo

Question 22

Granulomatous lymphadenitis differentials

Answer 22

Mycobacteria
Fungal infection (blastomycosis, histoplasmosis, coccidiomycosis)
Sarcoid
Kikuchi
Cat-scratch, yersinia, lymphogranuloma venerum
Foreign body granulomas

Question 23

ALCL histologic features

Answer 23

Horseshoe/doughnut cells characteristic
Sinusoidal
Immuno: CD30 (cytoplasmic, golgi), CD45, T-cell phenotype (can lose some antigens), null cell (but TCR rearrangement on genetic), EMA, ALK1
PAX-5 always -ve
Genetics: t(2;5) translocation ALK-NPM

Question 24

ALCL clinical features

Answer 24

Bimodal age
Lymphadenopathy and B symptoms
Extranodal masses - skin, bone, ST, lung, liver
Prognosis related to ALK (favourable)

Question 25

Lymphoplasmacytic lymphoma clinical

Answer 25

Older males Rare IgM paraproteinaemia Ass c Waldenstrom's MG and bone marrow involvement

Question 26

Lymphoplasmacytic lymphoma histology

Answer 26

Spectrum of small lymphocytes, plasmacytoid lymphocytes, plasma cells, immunoblasts Paracortial infiltration, sinuses intact Ducher bodies (nuclear), Russel bodies (cytoplasmic) CD19, 20, surface Igs, IgM +ve CD5, CD10 -ve Chromosome 6 deletion in WM

Question 27

Extranodal NK/T-cell lymphoma, nasal type histology

Answer 27

``` Angioinvasive, angiodestructive CD2 +ve, CD3, CD56 NK: TCR ab and yb -ve T-cell: positive EBV +ve ```