Haematology - MPN Flashcards
Components and functions of lymphatic system
Components:
- Lymph
- Lymphatic vessels
- lymphatic trunks (Lumbar, intestinal, bronchomediastinal, subclavian, jugular)
- lymphatic ducts (thoracic duct, right lymphatic duct)
- Lymphatic organs (Primary - BM, Thymus; Secondary - LN, Spleen, MALT, GALT, Tonsils)
Functions:
- Excess interstitial fluid drainage
- Immune response
- Dietary lipid and lipid-soluble vitamin transport and absorption
Spleen
- Functions (4)
- General structure
Function:
- Hematopoiesis in fetal life
- Filter circulating blood: remove old/ abnormal RBC
- Immune response: Antibody production, antigenic stimulation
- Blood storage
General structure:
- Fibrous capsule with trabeculae extension
- Red pulp (periphery): Splenic sinuses and splenic cords (Billroth cords) remove old RBC and drain into splenic veins
- White pulp (central) - Follicles, periarterial lymphatic sheath (PALS), Marginal zone for proliferation and antigenic stimulation of B cells, APCs in marginal zone
Main causes of splenomegaly *****
Hemolysis
- Hereditary causes: spherocytosis, thalassaemia intermedia, HbH disease
- Autoimmune haemolytic anaemia
Infection:
- Malaria
- TB, infective endocarditis
- EBV, CMV, HIV
Immune-mediated:
- Felty syndrome (RA)
Vascular congestion
Malignant Infiltration
Storage disease: Gaucher disease
Causes of vascular congestion causing splenomegaly
- Blockage of flow and blood pooling in red pulp
- Cirrhosis or non-cirrhotic portal hypertension
Post-hepatic:
- Budd-Chiari syndrome
- IVC obstruction
- Right heart failure
Intra-hepatic
- Liver cirrhosis
Pre-hepatic
- Portal vein thrombosis
- Splenic vein thrombosis
Malignancies that cause splenomegaly
- Chronic Leukaemia: CML, CLL
- Acute leukaemia: ALL
- Myeloproliferative neoplasm:
- Primary myelofibrosis
- Polycythaemia vera
- Essential thrombocythaemia - Lymphoma
History taking for Splenomegaly
Basic particulars: Age, gender, race
Splenomegaly compressive S/S: Abdominal fullness, Early Satiety
Haematological malignancy S/S:
- Pancytopenia S/S: thrombocytopenia and bleeding tendency, anaemia S/S, frequent infections …etc
- Bone pain, pathological fractures
Residence and travel history (infective causes)
Constitutional symptoms (malignancies)
Family history (storage diseases)
Physical exams for splenomegaly
General:
Anemia: Pallor, jaundice, Tachycardia, cyanosis
Thrombocythemia: bruising, deep-seated bleeding, mucocutaneous bleeding in gum/ mouth
Constitutional/ CA: Lymphadenopathy (Epitrochlear nodes, Axillary nodes, Cervical nodes), cachexia/ muscle wasting, bony tenderness
Specific Etiologies:
- Infections: Rash, retinal lesions (CMV, toxoplasmosis)
- Autoimmune diseases: arthralgia due to Felty’s syndrome (due to RA), Gout (due to MPD), Connective tissue disease
- Leukemia: e.g. testicular/ mediastinal mass (ALL)
Splenomegaly:
- Size below costal margin
- Confirm spleen: LUQ mass, moves down with respiration, cannot get above it, Dull on percussion, splenic notch present
- Associated hepatomegaly, lymphadenopathy
- Stigmata of liver disease
Ddx splenomegaly by size
Massive: CML, Myelofibrosis
Moderate: Portal hypertension, haematological malignancies
Minimal: Haemolytic anaemia (Thal. intermedia, HbH disease), Autoimmune cytopenia (ITP, AIHA), Infective causes
D/dx splenomegaly by incidence
Common:
→ Haematological malignancy, eg. lymphoma, leukaemia, MPN
→ Portal hypertension, eg. cirrhosis, splenic v. obstruction
→ Haemolytic anaemia, eg. thal intermedia, HBH disease, AIHA, hereditary spherocytosis
Rare:
→ Chronic inflammatory or A/I disease
→ Infections, eg. IE, schistosomiasis, malaria
Extremely uncommon:
→ Certain CAs,eg. splenic lymphoma with villous lymphocytes, hairy cell leukaemia
→ Certain infections, eg. hepatosplenic candidiasis, chronic malaria infection
→ Storage diseases
First line investigations for splenomegaly
Investigations:
- CBC with diff.
- Clotting profile
- LFT
- HbsAg
- Imaging of abdomen: USG, CT, PET-CT
Post-splenectomy/ Hyposplenism features on PBS
Howell-Jolly bodies + nucleated RBC
Outline the transition of normal hematopoietic stem cell to myeloid malignancies
AML
- Genetic cause
- Peripheral blood changes
- BM exam findings
- Two-hit mutations: Somatic mutation of TET2, IDH1/ IDH2 confers proliferative advantage and impairs differentiation
- Pancyotpenia due to BM infiltration, Variable WBC levels, Myeloid blast cells
- BM infiltration by leukaemic blasts, reduced normal haemopoietic cells
MPN
- Genetic cause
- Peripheral blood changes
- BM exam findings
- Examples
- Gain-of-fx mutations in pro-growth signalling
Eg. BCR-ABL1, JAK2, MPL, CALR - Increase cell count in 1 or more lineages, non-dysplastic cells
- Hypercellular with ↑progenitor cells, Effective haemopoiesis with normal differentiation
- Examples:
CML (BCR-ABL Positive)
Polycythaemic vera, Essential thrombocythaemia, Primary myelofibrosis, CNL, CEL (BCR-ABL negative)
MDS
- Genetic cause
- Peripheral blood changes
- BM exam findings
- Loss-of-fx mutations in terminal differentiation
- Pancytopenia, Morphology dysplastic
- Hypercellular marrow, Ineffective haemopoiesis with aberrant differentiation, N/↑ blasts <20%