Haematology JC049: Generalised Lymphadenopathy: Differential Diagnosis And Principle Of Management

Question 1

Distribution of LN in the body

Answer 1

Areas concentrated with LN:
1. **Cervical LN
2. **Axillary LN
3. Thymus (e.g. picked up when widened mediastinum)
4. Spleen (e.g. enlarged LN)
5. Lymphatics of upper limb (esp. **Epitrochlear, back of medial side of elbow)
6. **Inguinal LN
7. Lymphatics of lower limb (e.g. ***Popliteal)

Other groups of LN:
8. Lymphatics of mammary gland
9. Thoracic duct
10. Cisterna chyli
11. Lumbar LN
12. Pelvic LN

Question 2

Cervical LN

Answer 2

***Important landmark:
- Hyoid bone lower border
- Cricoid bone lower border

Level 1:
- Submental
- Submandibular

Level 2 (above Hyoid):
- Superior cervical

Level 3 (below Hyoid, above Cricoid):
- Middle cervical

Level 4 (below Cricoid):
- Lower cervical

Level 5:
- Posterior cervical
- Supraclavicular

Level 6:
- Anterior cervical

Level 7:
- Infraclavicular + Mediastinal

Others:
- Preauricular
- Postauricular
- Parotid
- Tonsillar
- Occipital

Question 3

***Causes of Generalised lymphadenopathy

Answer 3

1. ***Infection
   - Bacterial: TB, Cutaneous infection, STD (e.g. Syphilis)
   - Viral: HIV, Infectious mononucleosis, Rubella
   - Fungal (uncommon unless immunocompromised): Cryptococcosis
   - Others: Rickettsial diseases (tick-borne), Toxoplasmosis etc.
2. Neoplastic
   - Haematological: **Lymphoma, **Leukaemia (esp. CLL)
   - Metastatic carcinomas
3. Inflammatory (uncommon, presentation can be ~ lymphoma)
   - **Castleman disease
   - **Kikuchi disease
   - **Kimura disease
   - Amyloidosis, Sarcoidosis
   - **Autoimmune diseases e.g. SLE, RA
4. Drug reactions (presentation can be ~ lymphoma)
   - ***Phenytoin
   - Hydralazine
5. Endocrine disease
   - **Hypothyroidism
   - **Addison’s disease

Question 4

Approach to Generalised lymphadenopathy

Answer 4

History:
1. ***Constitutional symptoms (e.g. fever, weight loss, night sweats)

2. ***Localising symptoms suggesting infection / malignancy (e.g. axillary LN in Ca breast, supraclavicular LN in Ca lung, Ca CRC)
3. ***Exposure (e.g. cat (toxoplasmosis), insect bite (tick-borne), travelling, venereal exposure (HIV, syphilis), IV drug use)
4. ***Medications (e.g. phenytoin, hydralazine)

Physical examination:
1. Pathology in drainage areas for localised lymphadenopathy (e.g. examine breast for axillary LN)

2. Nature of LN
   - size (SLE, RA: modest size, Lymphoma: much bigger)
   - **consistency (Lymphoma: rubbery, Metastasis: hard)
   - **fixation (Infiltrative nature e.g. metastasis)
   - ***tenderness (Infection)
3. Associated signs e.g. ***hepatosplenomegaly (e.g. haematological malignancy), abnormal abdominal mass, SVC obstruction (swollen face, arms, dilated veins, widened mediastinum on CXR), cervical LN

Investigations (depends on presumptive diagnosis):
1. ***Proper biopsy generally recommended —> Histological appraisal to make definitive diagnosis (unless transient / too small / certain that it is reactive / benign in nature)

Question 5

LN biopsy

Answer 5

1. Fine needle aspiration
   - if presumptive diagnosis / one of ddx is Lymphoma —> FNA is **useless (∵ only cells does not tell much)
   —> not informative, time-consuming (2 weeks), delay in diagnosis
   - Only role: Only suspect to have **Metastatic carcinoma (i.e. carcinoma cells in LN e.g. NPC)
2. Excisional biopsy (recommended)
   - take whole LN out —> ***Histology —> allow sub-classification (e.g. lymphoma)
3. Incisional / Core biopsy
   - only when Excisional biopsy not timely available / patient too frail
   - amount of tissue less than desirable vs Excisional biopsy

Question 6

***Lymphoma

Answer 6

• One of most common cancers in HK
• Non-Hodgkin Lymphoma (most common lymphoma, 3% of all cancers)

Less common lymphoma in HK vs Caucasians:
1. Follicular lymphoma
2. CLL / SLL (small lymphocytic lymphoma)

More common lymphoma in HK vs Caucasians:
1. NK/T cell lymphoma
- AITL
- PTCL-NOS
- ALC
- ***Extranodal NK/T lymphoma (much more common)

Question 7

***WHO classification of Lymphoid malignancies

Answer 7

Big categories
1. Precursor lymphoid neoplasms
2. Mature B-cell neoplasms
3. Mature T- and NK- cell neoplasms
4. Hodgkin lymphoma
5. Immunodeficiency-associated lymphoproliferative disorders

Question 8

Basic concepts of Lymphoma

Answer 8

Big 2 divisions:
Hodgkin lymphoma (B-cell origin) (10% all lymphoma)
- unique histological hallmarks e.g. ***Reed-Sternberg cell (pathognomonic sign), characteristic cellular background of small lymphocyte plasma cells

Non-Hodgkin lymphoma (90%)
- ***B cells lymphoma (commonest)
- T cell lymphoma (uncommon)
- NK cell lymphoma (rare)

Question 9

Epidemiology of Lymphoma

Answer 9

• Causes largely ***unknown
• May be related to infection with viruses
  —> **EBV
  —> HTLV-1 (Human T-cell lymphotropic virus type 1)
  —> **HIV
  —> ***HCV
• Disease incidence ↑ with age
• Specific subtype:
  1. **Gastric MALT lymphoma (associated with **H. pylori)
  —> ***MALT (mucosa-associated lymphoid tissue) (secondary lymphoid tissue)
  2. Immunodeficiency-associated lymphoproliferative disorder (PTLD)

Question 10

B cell lymphoma

Answer 10

High grade (grow very fast but curable)
- **Diffuse large B cell lymphoma (DLBCL: most common lymphoma) (瀰漫性大B淋巴瘤)
- **Burkitt lymphoma (prototype of fastest growing lymphoma, dangerous but uncommon)

Low grade (slow growing, may disappear but high recurrence, not quite curable)
- Follicular lymphoma
- MALT lymphoma (very slow growing)

Question 11

Clinical presentation of Lymphoma

Answer 11

Can present with different symptoms:
1. Enlargement of involved tissue
- **Lymphadenopathy
- **Extranodal lesions (e.g. brain lesions in primary CNS lymphoma)

2. ***Constitutional symptoms
   - fever
   - weight loss (>10% BW in 6 months)
   - night sweat
3. Rash, Pruritis (paraneoplastic manifestations, sometimes lymphoma cells can also deposit in skin —> skin biopsy necessary)
4. Cytopenia (infiltrated BM by lymphoma cells)

Question 12

Clinical evaluations of Lymphoma

Answer 12

1. Time course of progression
   - when first noticed
   - progressive in size?
2. Affected systems
   - ***Extranodal involvement
   —> confusion, hemiplegic in primary CNS lymphoma
   —> breast ulcer in Breast lymphoma
   —> renal failure due to hydronephrosis in Renal lymphoma
3. Diagnosis
   - Excisional biopsy to properly diagnose subtypes of lymphoma
4. Causes
   - Viral: **EBV, **H. pylori
5. Staging
6. Preparation of treatment
   - e.g. organ functions, prior infections / ***risk of reactivation (HBV, TB)
   - good cardiac, lung function

Question 13

***Staging system for Lymphoma

Answer 13

***Ann Arbor system
- originally apply to Hodgkin only (spread along LN system)
- now also apply to Non-Hodgkin lymphoma (but can be problematic ∵ does not follow LN system)

Stage 1:
- 1 group of LN

Stage 2:
- 2 groups of LN

Stage 3:
- ***spread across Diaphragm
- if involve spleen: “3s”

Stage 4:
- diffuse involvement of ***extra-lymphatic (Non-lymphoid tissue: Bone, BM, Liver) (NOT spleen: already a lymphoid tissue)

Each stage can be categorised into:
- A: Asymptomatic
- B: Presence of constitutional symptoms
- E: Single extra-lymphatic (extra-nodal) site (e.g. single breast lymphoma lump: 1E) (vs Diffuse extra-lymphatic site: 4)

Question 14

***Prognosis of NHL (DLBCL) patients when treated with Doxorubicin-containing regimen

Answer 14

International Prognostic Index (***APLES)
1. Age >60
2. Performance status (ECOG (self notes)) >1
3. LDH >1x normal
4. Extranodal sites >1
5. Stage 3/4

Risk category:
- Low (L): 0-1
- Low intermediate (LI): 2
- High intermediate (HI): 3
- High (H): 4-5

However, nowadays know more about Diffuse Large B Cell Lymphoma (DLBCL)
—> Heterogenous (have different subtypes, ∵ different gene expression —> different **cell of origin)
1. **GCB (Germinal Centre B Cell-like DLBCL)
2. ***ABC (Activated B Cell-like DLBCL)
—> Use Immunohistochemistry
—> different GCB vs Non-GCB
—> able to define Prognosis better
—> GCB: better outcome vs ABC (using standard chemotherapy regimen)

Other protein markers important to define prognosis:
1. **MYC (proliferative marker)
2. **BCL-2 (anti-apoptotic marker)
3. ***BCL-6 (anti-apoptotic marker)
- MYC + BCL-2: double-expressor
- MYC + BCL-2 + BCL-6: triple-expressor
—> Inferior outcome

**Implications:
- Must do **IHC staining for all NHL patients

Question 15

Therapeutic strategies for Lymphoma

Answer 15

1. **Multi-agent chemotherapy + **Radiotherapy (standard, mainstay)
2. Immunotherapy
   - **Monoclonal Ab: +/- Drug conjugate (ADC)
   - **Immune checkpoint inhibitors
3. ***CAR-T cell therapy
4. ***HSCT
5. Small molecules: BTK / PI3K / BCL-2 inhibitors
6. Epigenetics: HDAC/EZH2 inhibitors
7. Immunomodulatory agents
8. MALT lymphoma: ***H. pylori eradication
9. Sezary syndrome: ***Extracorporeal photopheresis

Question 16

***Chemotherapy regimens

Answer 16

Multiple agents + Different MOA

Hodgkin lymphoma:
***ABVD
- Adriamycin (aka Doxorubicin: anthracycline)
- Bleomycin (anti-metabolite)
- Vinblastine (inhibit microtubule formation)
- Dacarbazine (alkylator)

Non-Hodgkin lymphoma
***CHOP
- Cyclophosphamide (alkylator)
- Hydroxydaunorubicin (exactly same as Adriamycin = Doxorubicin)
- Oncovin (Vincristine, ~Vinblastine, inhibit microtubule formation)
- Prednisolone

Question 17

Radiotherapy and Surgery

Answer 17

Radiotherapy (not in all patients):
1. **Consolidation (if residual tumour)
2. **Relief of obstruction
3. Palliative treatment (if patients too frail for chemo)

Surgery:
1. ***Tumour bleeding + obstruction (e.g. decompression of spine, removal of bleeding site)
2. Localised + Indolent lymphoma (e.g. only single LN involved)

Others:
- Symptomatic treatment (e.g. pain control, anti-emetic)
- Psychosocial support

Question 18

2. Immunotherapy

Answer 18

1. Monoclonal Ab
2. Antibody-drug conjugate (ADC)
3. Immune checkpoint inhibitors

Question 19

Monoclonal Ab

Answer 19

Anti-CD20 Ab
- ***Rituximab (1st in class, chimeric Ab)
- Ofatumumab (different epitope, human Ab)
- Obinutuzumab (same epitope as Rituximab, superior efficacy, human Ab)

MOA:
Ab bind to tumour cells (B cells) expressing CD-20
1. **Direct cytotoxic effect —> induce apoptosis
2. **Fix complement (C1q) —> MAC —> Complement-mediated lysis
3. ***ADCC (NK cells, CTL recognising Fc fragment of Ab)

Question 20

Antibody-drug conjugate (ADC)

Answer 20

3 components:
1. Site-specific monoclonal Ab
2. ***Cytotoxic drug
3. Functional linker that bind Cytotoxic drug to Ab

MOA:
ADC bind to Ag of tumour cell
—> Endocytosis of Ag-ADC complex
—> Lysosomal degradation
—> Cytotoxic drug released from Ab
—> Cytotoxic drug causes **cell cycle arrest
—> **Apoptosis via DNA / microtubule disruption

ADC:
1. Brentuximab vedotin
- Anti-CD30 mAb + ***MMAE (monomethyl auristatin E) (inhibit microtubule formation)
- for classical HL, PTCL (express CD30)

2. Polatuzumab vedotin
   - Anti-CD79b (B cell marker) mAb + MMAE
   - for relapsed / refractory DLBCL (in combination with Rituximab / other chemo)

SE (Vinca alkaloid):
- ***Peripheral neuropathy
- Cytopenia

Question 21

Immune checkpoint inhibitors

Answer 21

Immune checkpoint mAb: Anti-PD1 / Anti-PDL1

Tumour cell express PDL1 (programme death ligand 1) that bind to PD1 on T cell
—> ***inactivate T cell (T cell exhaustion phenomenon: a negative regulation)

Anti-PD1 / Anti-PDL1 prevent negative regulation
—> T cell remained activated
—> kill tumour cell

***Hodgkin lymphoma:
- like to use immune checkpoint —> ∴ Anti-PD1 / Anti-PDL1 work effectively against HL

However some lymphoma subtype not use immune checkpoint —> Anti-PD1 / Anti-PDL1 less effective

Question 22

3. CAR-T cell therapy

Answer 22

CAR: **Chimeric Ag Receptor
- take single chain **Fv region of normal Ab —> designed for specific targets of CAR (i.e. any tumour Ag e.g. CD19: expressed exclusively in B cells)
- no need MHC for binding
- bound on T cell —> recognise tumour Ag —> proliferation

Features of CAR (混種):
1. Recognise cell surface protein (**not MHC restricted)
2. Built in **co-stimulatory signals (CD28)
3. Built in ***effector (signal T cell proliferation)

Normal T cell receptor (TCR):
- TCR: bind to MHC, tumour peptide
- require co-stimulator (e.g. CD28, 41BB)
- CD3: effector responsible for signaling

Process:
Remove blood from patient to get non-cancerous (normal) T cells
—> Gene transduction (using retrovirus)
—> T cell can make CAR (i.e. become CAR T cells) (“enhanced soldiers”)
—> Grow millions of CAR T cells in lab
—> Infuse CAR T cells back into patient
—> CAR T cells bind to cancer cells and kill them

Question 23

Castleman disease

Answer 23

• Aka ***Angiofollicular LN hyperplasia
• Inflammatory cause of Lymphadenopathy
• ***IL-6 mediated

Diagnosis:
- Histological (must take out LN)

2 histopathologic types:
1. Hyaline vascular subtype
- regressed germinal centre in follicles
- follicles penetrated by ***sclerotic (hyaline) blood vessels (“lollipop lesions”)
- follicles with expanded mantle zone composed of concentric layers of small lymphocyte (“onion skin”)

2. Plasma cell subtype
   - expanded germinal centre
   - sheets of mature ***plasma cells within interfollicular region

Clinical features:
1. Unicentric CD (50%)
- Solitary lymphadenopathy
- No constitutional symptoms
- Normal laboratory tests
- Surgical resection to cure

2. Multicentric CD (i.e. >=2 LN regions) (50%)
   - **HHV8 associated / Idiopathic (HHV8 negative)
   - some associated with POEM / TAFRO syndrome
   - **Constitutional symptoms
   - Hepatosplenomegaly, Fluid accumulation (i.e. pleural effusion, ascites), Pneumonitis, Rash
   - **↑ ESR / CRP, anaemia, ↑/↓ platelet, renal dysfunction / proteinuria, **polyclonal hypergammaglobulinaemia (vs monoclonal in lymphoma / myeloma, ∵ inflammatory), **hypoalbuminaemia (∵ negative acute phase reactant + proteinuria)
   - **IL-6 inhibitor (Siltuximab) / IL-6R inhibitor (Tocilizumab)
   - Other treatment: Immunosuppressant, Chemotherapy

POEM syndrome:
- Polyneuropathy
- Organomegaly
- Endocrinopathy
- Monoclonal gammopathy

TAFRO syndrome:
- Thrombocytopenia
- Anasarca (generalised swelling ∵ hypoalbuminaemia)
- Fibrosis of BM
- Renal dysfunction
- Organomegaly

Question 24

Kikuchi disease

Answer 24

• Aka ***Histiocytic necrotising lymphadenitis
• Inflammatory cause of Lymphadenopathy

Clinical presentation:
- Asian young **women with tender + small cervical LN, **fever +/- rash

Laboratory tests:
- ***Neutropenia

Treatment:
- ***NSAID

Question 25

Kimura disease

Answer 25

• Aka ***Angiolymphoid hyperplasia with eosinophilia
• Inflammatory cause of Lymphadenopathy

Clinical presentation:
- Asian young **men with cervical LN / SC nodules in H+N region but **asymptomatic

Laboratory tests:
- **Eosinophilia
- **↑ IgE

Treatment:
- Surgical removal (for ***cosmetic reason)

Question 26

Metabolically active lesions causing widened mediastinum DDx

Answer 26

1. ***Thymoma
2. ***Malignant Lymphoma
   - Hodgkin lymphoma
   - Primary mediastinal B-cell lymphoma (subtype of DLBCL)
   - T-lymphoblastic lymphoma
3. ***Acute Lymphoblastic Leukaemia
   - T-ALL
4. ***Lung carcinoma
5. ***Germ cell tumour

Question 27

Infectious mononucleosis

Answer 27

Clinical presentations:
- Fever
- Lymphadenopathy
- **Atypical lymphocytosis
- **Transaminitis (↑ ALT, AST)
- Palatal petechiae

Investigation:
1. **Monospot test (if EBV in origin, test for Heterophile Ab)
2. **CMV serology (IgG negative, IgM positive)
3. ***EBV serology (IgG negative, IgM positive)
4. DNA of CMV, EBV