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Lymphoid Proliferations.pptx

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Safiya James
Safiya James

Lymphoid proliferations can be benign or malignant. Benign causes include infections while malignant causes include lymphomas. Lymphomas are divided into Hodgkin's lymphoma and non-Hodgkin's lymphoma. Hodgkin's lymphoma is characterized by Reed-Sternberg cells while non-Hodgkin's lymphoma can be of B-cell or T-cell origin. Different cell markers are used to identify the specific cell type by flow cytometry and immunohistochemistry. Investigation of lymph node enlargement includes history, examination, blood tests, imaging and biopsy to determine if the cause is benign reactive hyperplasia or malignant lymphoma or metastatic carcinoma.

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Lymphoid Proliferations Characteristics of Lymphocytes They originate in the bone marrow & differentiate in primary lymphoid tissues: They circulate in the peripheral blood & migrate into secondary organs (ex: lymph nodes). Differentiating the Types of Lymphocytes Flow cytometry and immunohistochemistry: use markers antibodies which will react with their specific type: All lymphocytes: CD45 B lymphocytes: CD20, CD79(a) T lymphocytes: CD2, CD3 (predominant), CD4, CD5, CD8. B cells express different antigens throughout their development: Phagocytic Cells Monocytes: WBC that differentiate into macrophages, involved in immunity. Histiocytes: phagocytic tissue monocytes that produce cytokines. Macrophages: histiocytes w/ more phagocytic function. Multinucleated cell: fused histiocytes. Dendritic cell: APC to T cell. Langerhan cell: APC. Causes of Enlarged Nodes Can be benign or malignant: Lymphoid Tissue Proliferation Clinical Signs: 1. Lymphadenopathy, splenomegaly, hepatomegaly 2. Thymic enlargement, marrow expansion 3. Masses in nasopharynx, GIT, etc. 4. Night sweats: very important (if patients comes in with night sweats worry if they have a lymphoma). 5. Recurrent infection: marrow produces immature cells that cant function; marrow failure reduced bone products anaemia, infection, bleeding. T cells Thymus; cell mediated immunity; 70% in blood; paracortex of nodal tissue. B cells Bone Marrow; humoral immunity; 10% in blood; cortex of nodal tissue. Null cells Not B/T cell marker responsive; 20% in blood; NK cells May react with T cells. Lymphopenia (Low lymphocyte count) Lymphocytosis (High lymphocyte count) Advanced HIV infection Congenital immune deficiency syndromes Steroids Chemotherapeutic drugs Autoimmune diseases Viral infection (infectious mononucleosis) Rare bacterial infections (Whooping cough, Tuberculosis, Brucellosis) Benign Reactive Hyperplasia Patterns: 1. Cortex follicular hyperplasia B cells in germinal centre of cortex mainly Non-specific reaction Infection/immune stimulation Macrophages may be present in follicle centre. 2. Paracortical hyperplasia T cells mainly 3. Sinus histiocytosis Dilated sinuses Histiocytes Lymphocytes Antigen presenting cells Journey through sinuses: afferent lymphatics sub- capsular sinuses cortical sinuses medullary sinuses efferent lymphatics (metastasis initially spreads to this part of the node). Most reactive nodes have a combination of these. Causes: 1. Infections (always discuss the types) Bacterial (syphilis, brucellosis, cat scratch disease) Viral (infectious mononucleosis) Protozoal 2. Granulomas (TB, Sarcoid, Crohns, Fungi) 3. Deposits (Amyloid) 4. Immune Reactions (Rheumatoid arthritis, SLE) 5. Storage Disorders (Gauchers disease - histiocytes/ macrophages contain undigested material) Classification Acute Reactive Lymphadenitis Lymphadenopathy secondary to bacterial or viral infection in the area drained by the lymph node. Lymph node is enlarged and tender ex: cervical nodes in acute streptococcal tonsillitis. Histology: Preserved architecture Follicular hyperplasia Neutrophilic infiltrate and abscess formation Chronic Reactive Lymphadenitis A response to chronic antigen exposure Immune-mediated/Collagen vascular disease: 1. Rheumatoid arthritis Generalised lymphadenopathy & follicular hyperplasia 2. Sj旦grens syndrome Increased risk of lymphoma & follicular hyperplasia 3. Systemic lupus erythematosus (SLE) --> Cervical lymphadenopathy & follicular hyperplasia Different markers are used for different stages of B cell proliferates; CD20 doesnt stain plasma cells -
Investigation of an Enlarged Lymph Node Diagnostic Questions: Is the node benign or malignant? If benign is there an identifiable cause for node enlargement? If malignant is it a carcinoma, lymphoma (most likely), melanoma or sarcoma? If it is a metastatic carcinoma, where is the primary site? 1. Proper history and clinical examination. Ask: Evidence of recent infection? Evidence of malignancy in adjacent lymphatic draining site? Any localising symptoms? Any weight loss? Any night sweats? Duration of lymphadenopathy? Are nodes sore/tender? 3. Investigations: FBC CRP (C-reactive Protein) indicates inflammation LDH indicates RBC lysis Viral screen Chest X-ray CT chest and abdomen Biopsy (to investigate histology) 1. Fine needle aspiration/biopsy 2. Incisional biopsy 3. Excision of whole node ensures that malignant portion is not missed & is thus the best sample. 4. Bone marrow trephine NB: enlarged retroperitoneal nodes present because theyre in the abdomen and need to be very large to be felt. Malignant (Lymph Node Enlargement) Causes: Primary: Lymphoma Leukaemia Secondary: Metastatic carcinoma commonest Metastatic melanoma Metastatic sarcoma rare Others i.e. Germ cell rare To investigate likely primary site of a metastasis in a node: Suspect the area which drains that node: Examples: 1. Metastasis in inguinal node due to melanoma of skin of lower limb (not squamous cell carcinoma because it rarely metastasises) 2. Metastasis in supraclavicular node upper GIT carcinoma, bronchogenic carcinoma, breast 3. Metastasis in cervical node nasopharyngeal carcinoma, oropharyngeal carcinoma, head and neck carcinoma, salivary glands, thyroid. 4. Metastasis in axillary node breast carcinoma 5. Melanoma check anal skin and retina for primary site. Histological features that identify type of malignancy: Morphological features that suggest a carcinoma: Keratin Squamous cell carcinoma Mucin Adenocarcinoma Tubules Adenocarcinoma If morphological features are not evident, we use tumour markers: Cytokeratin CK Epithelial Metastatic Carcinoma Vimentin Mesenchymal CD45 Common Leucocyte Antigen Lymphoma S100P and HMB45 Melanoma o If an undifferentiated malignancy in a lymph node is CD45 (Common Leucocyte antigen) positive, then diagnosis is of a LYMPHOMA. o If an undifferentiated neoplasm is Cytokeratin (CK) positive it is a metastatic carcinoma.
Lymphoma Definition Malignant neoplasm of lymphoid cells that may be nodal or extra-nodal. Divided into Hodgkin & non-Hodgkin lymphoma. Hodgkin Lymphoma (HL) 20% Characteristics Malignancy of Reed-Sternberg (RS) cells and Hodgkin cells. They secrete cytokines that attract benign reactive cells including lymphocytes, plasma cells, macrophages and eosinophils and may lead to fibrosis. RS cells: bi-nucleated B cells with large vesicular nuclei and prominent eosinophilic (pink) nucleoli. Hodgkin cells: larger mononuclear RS cells. Bimodal Age Distribution: Peaks: 20s-30s (60-70%) & >60s. Usually presents as an enlarged, firm node usually cervical. Immunohistochemistry Markers CD15+, CD30+ and no CD20, CD45. Clinical Presentation Commonest: persistent lymphadenopathy (usually in neck or mediastinum). Mediastinal superior vena cava syndrome. B Symptoms (FAWN): fever, night sweats, weight loss, anaemia. Pruritis (itchy skin) & pain located at the site of nodal enlargement & which is exacerbated by drinking alcohol. Hepatosplenomegaly. Extra nodal swelling. Grading/Rye Classification Based on microscopic grounds: amount of lymphocytes, types of RS cells & degree of fibrosis: 1. Nodular Lymphocyte Predominant Hodgkin Lymphoma A controversial entity in that the RS cells stain positively for B cell markers (and so may actually be a B cell NHL). The popcorn RS cell is characteristic. Lymphocytes make up the reactive cell population and may be so numerous as to obscure the often scanty RS cells. 2. Classical Hodgkin Staging (Ann Arbor Staging) & Diagnosis Done radiologically using: chest x-ray, CT, MRI, PET (after some treatment to monitor lymph node size), bone aspirate, bone trephine, presence/absence of B symptoms, LDH level (dead lymphocytes), performance index (determines how well patient will withstand treatment) Stage 1: 1 lymph node region/1 lymphoid organ. Stage 2: 2 or more lymph node regions on the same side (LHS or RHS) of the diaphragm. Stage 3: nodes both sides of diaphragm. Stage 4: involvement of extra-nodal sites: liver, bone, lung, and nodes. Prognosis 80% excellent response to treatment and many cured. Prognosis worsens with presence of B symptoms, age > 60, stage III or IV and increased LDH level of activity. Many associated with EBV infection. Lookalikes: need to be separated from Hodgkin disease using Immunomarkers: Ki1 Lymphoma (anaplastic large cell lymphoma) T cell lymphoma T cell rich B cell lymphoma Non Hodgkin Lymphoma (NHL) 70- 80% Characteristics/Classification Commonly extra-nodal: 70-80% The REAL classification system and divides diseases into T cell, B cell and null cell lymphomas. Can be B cell or T cell, low grade (small cell size) or high grade (large cell size). Immunohistochemistry Markers Used CD20 and CD79 B Cell Lymphomas CD3 T Cell lymphomas BCL2 and CD10 Follicular lymphoma CD5 and CD23 Small cell lymphocytic Lymphoma Cyclin D1 Mantle cell lymphoma Diagnostic Steps Immunohistochemistry is not sensitive enough for Dx. Molecular studies are required to show monoclonality e.g. gene rearrangements. Clonality to diagnose malignancy Monoclonal (important) B Cell Lymphomas Ig gene rearrangements. T Cell lymphomas T cell receptor rearrangements. IHC to diagnose type of lymphoma. Ann Arbor Staging is also used here. Comparison Table Most common HL. Thick bands of sclerotic collagen divide the lymph node into nodules. RS or Hodgkin cells. Eosinophils are prominent. Granulomas and necrosis are frequent and may lead to confusion with tuberculosis. The rarest & most aggressive form of HL. Pleomorphic RS cells. Sclerosis may be prominent. HL NHL Incidence Less than NHL More than HL Cell of origin B-cells B or T cells Type of Cell RSC No characteristic cells Age Commonly young adults Older adults L.N spread Contiguously (orderly) Sporadic B-symptoms Common Less common (>20% of patients) Extra-nodal Less common More common Cure Most Some
Non-Hodgkin Lymphoma (NHL) contd B cell NH-Lymphomas: B Cell Lymphoma Cell of Origin & Markers Pathogenesis & Presentation Epidemiology & Prognostics Follicular B Cell Lymphoma Centrocyte/ Centroblast BCL2 & CD10. Definition: Small neoplastic B cells form follicle-like nodules. Cause: t(14;18) BCL2. Pathogenesis: Antiapoptotic BCL2 gene on chromosome 18 translocated to chromosome 14 overexpression of anti-apoptotic proteins B cell proliferation. NB: Follicular Lymphoma is BCL2 positive, monoclonal, destroys lymph node architecture and doesnt have tingible body macrophages where as reactive follicular hyperplasia is the opposite. One of the commonest lymphomas: Affects >50 years 60% stage III or IV at presentation. Rarely get cured but indolent (not aggressive) and progressive disease. 70% - 5 year survival. 20% - transform to high grade. Small Cell Lymphocytic Lymphoma Lymphocyte CD5 & CD23 Definition: Chronic lymphocytic leukaemia that has spread to/manifested in the tissues. Presentation: Widespread adenopathy, Splenomegaly, decreased Ig increased infection 5-10% Richters Syndrome high grade transformation (cells become big) Commonly stage III or IV because asymptomatic at presentation. Mantle Cell Lymphoma Mantle cells Cyclin D1 Definition: diffuse replacement of node by malignant/neoplastic mantle B-cells. Cause: t(11;14) Cyclin D1. Pathogenesis: Cyclin D1 gene on chromosome 11 translocated to chromosome 14 inc. cyclin D1 more cells enter G1/S phase increased proliferation. <5% of all lymphomas (rarer): Age distribution: peak 60-70 years. Often high stage at presentation . 20-40% - 5 year survival. Marginal Zone Lymphoma (ex: Maltoma GIT) Marginal zone cells Definition: Extra-nodal lymphomas that are usually low grade. Predisposing Factors: Antigen Challenge. Pathogenesis: associated with and found in chronic inflammatory conditions: GIT HLO in stomach, Thyroid Hashimotos, Salivary gland Sjogrens, Lungs Due to increased cell turnover precipitated by the underlying condition Diffuse Large Cell B Cell Lymphoma Centroblasts Definition: Large mononuclear neoplastic B cells proliferate and can spread to extra-nodal sites. Commonest high grade B cell lymphoma: Aggressive but curable. Lymphoblastic B Cell Lymphoma Lymphoblast Rare (Majority are T cell LBLs); Bone lytic lesions. Many children and young adults Burkitts Lymphoma Lymphoblast, EBV + & activated c-Myc Definition: Type of lymphoblastic lymphoma. Intermediate B cell proliferation. Cause: t(8;14) c-Myc. Pathogenesis: EBV associated, c-Myc translocation from chromosome 8 to 14 present deregulation of oncogenic function increased cell growth. Clinical Presentation: extra-nodal mass in jaw, GIT, gonads in young adults/kids. IHC starry sky appearance on microscopy. African form jaw. Sporadic form abdomen. Rare in Europe. Occurs in children and adolescents. Lymphocyte, Mantle cell, Marginal cell, Lymphoblast, Immunoblast, Centrocyte/Cleaved FCC follicle centre cell Centroblast/Non cleaved FCC Plasma cell large B cells F.C.C. Cleaved & non-cleaved Aka centrocytes/ centroblasts Histiocytes Mantle cells Marginal Cells Plasma cell Lymphocytes L O W G R A D E H I G H G R A D E
T cell NH-Lymphomas Low Grade 1. Mycosis Fungoides T cell lymphoma producing scaly, pruritic, well-demarcated skin plaques and patches. In the later stages of the disease, mushroom-shaped tumours develop within the plaque lesions, and ultimately lymphadenopathy and hepatosplenomegaly can develop. Occurs in adults 12 year survival 2. Sezary syndrome Cutaneous (skin) T-cell lymphoma with leukaemic dissemination of mutated T cells (which distinguishes it from mycosis fungoides). It thus becomes a T cell leukaemia and is considered an advanced stage of mycosis fungoides. 3. T cell Chronic Lymphocytic leukaemia (CLL) High Grade 1. Peripheral T CellLymphoma (most high grade are classified as this) 2. Enteropathy associated T CellLymphoma (EATL) It is a complication of celiac disease, occurs in the small bowel and is commoner in those with poor dietary control. 3. T Lymphoblastic Lymphoma Young adults but very rare Rapid enlargement of nodes On histology, large lymphoid cells that react with T lymphocyte markers 4. T Adult T cell leukaemia/lymphoma Rare Japan/Caribbean HTLV1 Virus Hypercalcaemia (PTH) Other Lymphomas 1. Extra-Nodal Lymphoma Lymphomas of mucosa and non-nodal tissue 2. Nasal Lymphoma High grade lymphoma of nose Null of NK cells Common in Asia but uncommon in Europe EBV associated Causes of Lymphoma 1. Antigen challenge: the first encounter between an immunocompetent lymphocyte and an invading antigen. 2. Viruses EBV associated with: Burkitts, Nasal lymphomas, Hodgkins (BNH) 3. Immunodeficiency 4. Radiation 5. Previous chemotherapy Leukaemia vs Lymphoma Summary of Management (for ALL NHLs) Diagnosis Radiologist takes the trucut Painless persistent enlargement of node 賊 B symptoms Loss of normal architecture (not reactive follicular hyperplasia) Monoclonality malignancy (determined by molecular studies of gene rearrangements) Hodgkin or Non Hodgkin Reed Sternberg cell Dx Hodgkins No RS cells Dx Non Hodgkins Small cells (Low Grade) or large cells High Grade) replace node Lymphoid markers are essential to type lymphoma correctly Molecular markers now being increasingly used Grade Rye Grading Stage Ann Arbor Staging CT, PET, BMT Treatment Rituximab B cell (CD20 monoclonal antibody) Chemotherapy Radiotherapy Bone marrow transplant Lymphoma Leukaemia High WCC >20,000 Normal WCC Patchy marrow involvement Extensive marrow replacement Little lymphadenopathy Prominent lymphadenopathy
Thymus The thymus arises from the endoderm of 3rd and 4th branchial pouch. It migrates down from the neck to the mediastinum where it houses T cells and produces hormones that allow them to mature further. Thymus gets smaller after birth and is almost completely atrophied in adults. Functions of Thymus Responsible for differentiation and direction of T cells Central role in cell mediated immunity Enlargement of Thymus 1. Myasthenia gravis 80% thymic hyperplasia autoimmune thymitis 80% AChr antibody against myeloid cells 15% get thymoma Treatment Thymectomy 2. Thymomas (epithelial neoplasm of thymus; oma doesnt indicate benign or malignant - can be either) May present with associated diseases: 30% myasthenia gravis Rheumatoid arthritis Sjogrens syndrome Anterior mediastinal mass NB: Prognosis behaviour correlates with grade 3. Lymphomas T cell most are T cell B cell 4. Germ cell tumours 5. Carcinoid tumours Spleen White pulp: lymphoid follicles (Malpighian bodies). Red pulp: venous sinuses & cords (lymphocytes). Weight: 120-150g. Functions of Spleen Splenic Atrophy Physiological old age. Sickle cell disease sickle cells get trapped in blood vessels that supply the spleen spleen becomes infarcted in areas heals by fibrosis small spleen. Coeliac disease idiopathic. Splenomegaly Splenomegaly causes: hypersplenism which is the enlargement of spleen for any reason causing destruction of blood cells and consequently a reduction in these cells in the peripheral blood anaemia, thrombocytopenia & leukopenia. Causes of splenomegaly include: 1. Congestive Cirrhosis of liver portal vein thrombus inc. pressure on the splenic vein. 2. Collagen Vascular Diseases (Autoimmune Disorders) Rheumatoid arthritis Systematic Lupus Erythematosus (SLE) Polyarteritis Nodosa (PAN) 3. Storage Disorders Hyperlipidaemias Lipid storage disorders Gauchers disease Neiman Picks Disease 4. Infections Malaria Leishmaniasis (protozoal) Infectious mononucleosis spontaneous rupture Brucellosis S.B.E subacute bacterial endocarditis Endocarditis septic emboli from endocarditis go to the spleen abscess. NB: Splenomegaly due to infection is more seen in children and when seen in adults more due to viral than bacterial infection (esp. infectious mono). 5. Amyloidosis 6. Disorders of blood & marrow Leukaemias and Lymphomas Haemolytic anaemia red cells broken down by histiocytes & macrophages in spleen gets bigger. Myelofibrosis myelo = fibrosis; spleen cant produce red cells & blood components so function taken over by the liver. Myeloproliferative disorders Myeloproliferative Cell Neoplasms/Disorders Clonal neoplastic proliferation of stem cells, affecting all cell lines of the bone marrow with variable clinical presentation and variable prognosis (excluding acute leukaemia). Diagnosis Clinical presentation (3 conditions) FBC BMT and BM aspirate Pathogenesis activating mutation in gene coding for tyrosine kinases. Characteristics 1. Arise from common stem cell cases with intermediate features 2. Frequent evolution of 1 type to another 3. Invariable involvement of more than 1 cell line due to an abnormal clone with increased sensitivity to growth factors. 4. Occur in people > 50 years 5. Splenomegaly 6. Mutation of the tyrosine kinase JAK2 (Janus kinase 2 gene). Causes increased sensitivity to intercellular signalling from growth factors. Presentation Concepts Excess of one cell type may cause a decrease of other cell types High content of one cell type may cause symptoms Anaemia and infection Bleeding/thrombosis Hyperviscosity syndrome Tumour Markers in Nodes & Spleen, Thymus and Bone Marrow 1. Haemopoiesis 2. Antibody formation 3. Cell sequestration 4. Cell destruction 5. Iron metabolism 6. Phagocytosis
1. Chronic granulocytic/myeloid leukaemia (commonest) 2. Myelofibrosis 60% JAK2 3. Polycythaemia rubra vera (RBC) 90% JAK2 4. Essential thrombocythaemia/ Thrombocytosis (Platelets) 60% JAK2 1) Chronic Myeloid/Granulocytic Leukaemia (CML/CGL) Neoplastic proliferation of stem cells that differentiate into mature myeloid cells, especially granulocytes (characteristically basophils). Characterised by Philadelphia fusion chromosome t(9;22) which results in a BCR-ABL fusion protein with increased tyrosine kinase activity. This is also an MPD (Myeloproliferative Disorder). Presentation Marrow replacement with/without failure anaemia, bleeding, bruising, infection. Marked leucocytosis 50,000 abnormal. Marked hepatosplenomegaly. Weight loss. Epidemiology Middle age 40-60 years. Diagnosis 1. WCC above 100,000 instead of 7,000 2. Increased blasts in the peripheral blood too many being released (shouldnt normally be there) can become a crisis. 3. PHI chromosome 22.9 (used to) 4. BCR-ABL rearrangement diagnostic of CML. 2) Myelofibrosis - 60% JAK2 Neoplastic proliferation of mature myeloid cells especially megakaryocytes. Primary Myelofibrosis: Megakaryocytes produce excess platelet-derived growth factor (PDGF) marrow fibrosis. Secondary Myelofibrosis: Metastases to marrow Radiotherapy to marrow Cytotoxic drugs Presentation Fibrosis reduces marrows haematopoietic capability migration of erythroid precursors to spleen & liver extramedullary haematopoiesis hepato- splenomegaly & poikilocytosis (abnormal RBCs). Loss of marrow cells Terminal blast crisis Life expectancy - 7 years Treatment Supportive Marrow stimulation +/- Splenectomy (cells being produced are being destroyed in the spleen remove it to salvage the few being produced) 3) Essential thrombocythemia/thrombocytosis (platelets) - 60% JAK2 Neoplastic proliferation of mature myeloid cells especially platelets. Presentation: Increased platelet count: 1 million; (normal: 350,000) Bleeding/thrombotic abnormalities Enlarged spleen Enlarged liver Treatment Hydroxyurea 4) Polycythaemia Rubra Vera 90% JAK2 Neoplastic proliferation of mature myeloid cells especially RBCs increased red cell volume. Primary Polycythaemia: Malignancy of red blood cells High Hb and Haematocrit Secondary Polycythaemia: High altitudes Congenital Heart Disease Tumours (e.g. renal cell carcinoma ) Erythropoietin production (e.g. renal carcinoma) Presentation Red face (jumping jacks JAK red face) Thrombotic and haemorrhagic events Increased Hb Enlarged spleen Marrow erythropoiesis Treatment 1. 1st line: Phlebotomies (older patients): remove excess cells by removing blood. 2. 2nd line: Hydroxyurea (myelosuppressive treatment) 3. Exclude secondary causes 4. Radiotherapy with 32P isotope. Prognosis: 50%= 12 year survival (usually terminal with blast crisis).
Investigations FBC Leukocyte ALK phosphatase (LAP) differentiates CML from other causes of leucocytosis BCR-Abl gene rearrangement Uric acid JAK2 BMT bone marrow trephine (always have to do this) Myelodysplastic Syndrome Smouldering neoplastic proliferation of stem cells of bone marrow, majority terminate after 1-3 years in leukaemia (more aggressive) occurs in younger ppl A pre-leukaemic disorder Usually low peripheral cell count with hypercellular marrow Often in Myeloproliferative cell neoplasms/disorders you have a high peripheral cell count and hypercellular marrow Associated with a variety of chromosomal abnormalities Diagnosis based on clinical haematological and bone trephine May follow previous chemotherapy treatment or may occur de novo Classification of myelodysplasia depends on which cell line shows the dominant abnormality. There are 8 different types These are difficult to diagnose and require cytogenetic studies and correlation between the marrow aspirate and the FBC etc Some will progress into Leukaemia within 2 years

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Lymphoid Proliferations.pptx

  • 1. Lymphoid Proliferations Characteristics of Lymphocytes They originate in the bone marrow & differentiate in primary lymphoid tissues: They circulate in the peripheral blood & migrate into secondary organs (ex: lymph nodes). Differentiating the Types of Lymphocytes Flow cytometry and immunohistochemistry: use markers antibodies which will react with their specific type: All lymphocytes: CD45 B lymphocytes: CD20, CD79(a) T lymphocytes: CD2, CD3 (predominant), CD4, CD5, CD8. B cells express different antigens throughout their development: Phagocytic Cells Monocytes: WBC that differentiate into macrophages, involved in immunity. Histiocytes: phagocytic tissue monocytes that produce cytokines. Macrophages: histiocytes w/ more phagocytic function. Multinucleated cell: fused histiocytes. Dendritic cell: APC to T cell. Langerhan cell: APC. Causes of Enlarged Nodes Can be benign or malignant: Lymphoid Tissue Proliferation Clinical Signs: 1. Lymphadenopathy, splenomegaly, hepatomegaly 2. Thymic enlargement, marrow expansion 3. Masses in nasopharynx, GIT, etc. 4. Night sweats: very important (if patients comes in with night sweats worry if they have a lymphoma). 5. Recurrent infection: marrow produces immature cells that cant function; marrow failure reduced bone products anaemia, infection, bleeding. T cells Thymus; cell mediated immunity; 70% in blood; paracortex of nodal tissue. B cells Bone Marrow; humoral immunity; 10% in blood; cortex of nodal tissue. Null cells Not B/T cell marker responsive; 20% in blood; NK cells May react with T cells. Lymphopenia (Low lymphocyte count) Lymphocytosis (High lymphocyte count) Advanced HIV infection Congenital immune deficiency syndromes Steroids Chemotherapeutic drugs Autoimmune diseases Viral infection (infectious mononucleosis) Rare bacterial infections (Whooping cough, Tuberculosis, Brucellosis) Benign Reactive Hyperplasia Patterns: 1. Cortex follicular hyperplasia B cells in germinal centre of cortex mainly Non-specific reaction Infection/immune stimulation Macrophages may be present in follicle centre. 2. Paracortical hyperplasia T cells mainly 3. Sinus histiocytosis Dilated sinuses Histiocytes Lymphocytes Antigen presenting cells Journey through sinuses: afferent lymphatics sub- capsular sinuses cortical sinuses medullary sinuses efferent lymphatics (metastasis initially spreads to this part of the node). Most reactive nodes have a combination of these. Causes: 1. Infections (always discuss the types) Bacterial (syphilis, brucellosis, cat scratch disease) Viral (infectious mononucleosis) Protozoal 2. Granulomas (TB, Sarcoid, Crohns, Fungi) 3. Deposits (Amyloid) 4. Immune Reactions (Rheumatoid arthritis, SLE) 5. Storage Disorders (Gauchers disease - histiocytes/ macrophages contain undigested material) Classification Acute Reactive Lymphadenitis Lymphadenopathy secondary to bacterial or viral infection in the area drained by the lymph node. Lymph node is enlarged and tender ex: cervical nodes in acute streptococcal tonsillitis. Histology: Preserved architecture Follicular hyperplasia Neutrophilic infiltrate and abscess formation Chronic Reactive Lymphadenitis A response to chronic antigen exposure Immune-mediated/Collagen vascular disease: 1. Rheumatoid arthritis Generalised lymphadenopathy & follicular hyperplasia 2. Sj旦grens syndrome Increased risk of lymphoma & follicular hyperplasia 3. Systemic lupus erythematosus (SLE) --> Cervical lymphadenopathy & follicular hyperplasia Different markers are used for different stages of B cell proliferates; CD20 doesnt stain plasma cells -
  • 2. Investigation of an Enlarged Lymph Node Diagnostic Questions: Is the node benign or malignant? If benign is there an identifiable cause for node enlargement? If malignant is it a carcinoma, lymphoma (most likely), melanoma or sarcoma? If it is a metastatic carcinoma, where is the primary site? 1. Proper history and clinical examination. Ask: Evidence of recent infection? Evidence of malignancy in adjacent lymphatic draining site? Any localising symptoms? Any weight loss? Any night sweats? Duration of lymphadenopathy? Are nodes sore/tender? 3. Investigations: FBC CRP (C-reactive Protein) indicates inflammation LDH indicates RBC lysis Viral screen Chest X-ray CT chest and abdomen Biopsy (to investigate histology) 1. Fine needle aspiration/biopsy 2. Incisional biopsy 3. Excision of whole node ensures that malignant portion is not missed & is thus the best sample. 4. Bone marrow trephine NB: enlarged retroperitoneal nodes present because theyre in the abdomen and need to be very large to be felt. Malignant (Lymph Node Enlargement) Causes: Primary: Lymphoma Leukaemia Secondary: Metastatic carcinoma commonest Metastatic melanoma Metastatic sarcoma rare Others i.e. Germ cell rare To investigate likely primary site of a metastasis in a node: Suspect the area which drains that node: Examples: 1. Metastasis in inguinal node due to melanoma of skin of lower limb (not squamous cell carcinoma because it rarely metastasises) 2. Metastasis in supraclavicular node upper GIT carcinoma, bronchogenic carcinoma, breast 3. Metastasis in cervical node nasopharyngeal carcinoma, oropharyngeal carcinoma, head and neck carcinoma, salivary glands, thyroid. 4. Metastasis in axillary node breast carcinoma 5. Melanoma check anal skin and retina for primary site. Histological features that identify type of malignancy: Morphological features that suggest a carcinoma: Keratin Squamous cell carcinoma Mucin Adenocarcinoma Tubules Adenocarcinoma If morphological features are not evident, we use tumour markers: Cytokeratin CK Epithelial Metastatic Carcinoma Vimentin Mesenchymal CD45 Common Leucocyte Antigen Lymphoma S100P and HMB45 Melanoma o If an undifferentiated malignancy in a lymph node is CD45 (Common Leucocyte antigen) positive, then diagnosis is of a LYMPHOMA. o If an undifferentiated neoplasm is Cytokeratin (CK) positive it is a metastatic carcinoma.
  • 3. Lymphoma Definition Malignant neoplasm of lymphoid cells that may be nodal or extra-nodal. Divided into Hodgkin & non-Hodgkin lymphoma. Hodgkin Lymphoma (HL) 20% Characteristics Malignancy of Reed-Sternberg (RS) cells and Hodgkin cells. They secrete cytokines that attract benign reactive cells including lymphocytes, plasma cells, macrophages and eosinophils and may lead to fibrosis. RS cells: bi-nucleated B cells with large vesicular nuclei and prominent eosinophilic (pink) nucleoli. Hodgkin cells: larger mononuclear RS cells. Bimodal Age Distribution: Peaks: 20s-30s (60-70%) & >60s. Usually presents as an enlarged, firm node usually cervical. Immunohistochemistry Markers CD15+, CD30+ and no CD20, CD45. Clinical Presentation Commonest: persistent lymphadenopathy (usually in neck or mediastinum). Mediastinal superior vena cava syndrome. B Symptoms (FAWN): fever, night sweats, weight loss, anaemia. Pruritis (itchy skin) & pain located at the site of nodal enlargement & which is exacerbated by drinking alcohol. Hepatosplenomegaly. Extra nodal swelling. Grading/Rye Classification Based on microscopic grounds: amount of lymphocytes, types of RS cells & degree of fibrosis: 1. Nodular Lymphocyte Predominant Hodgkin Lymphoma A controversial entity in that the RS cells stain positively for B cell markers (and so may actually be a B cell NHL). The popcorn RS cell is characteristic. Lymphocytes make up the reactive cell population and may be so numerous as to obscure the often scanty RS cells. 2. Classical Hodgkin Staging (Ann Arbor Staging) & Diagnosis Done radiologically using: chest x-ray, CT, MRI, PET (after some treatment to monitor lymph node size), bone aspirate, bone trephine, presence/absence of B symptoms, LDH level (dead lymphocytes), performance index (determines how well patient will withstand treatment) Stage 1: 1 lymph node region/1 lymphoid organ. Stage 2: 2 or more lymph node regions on the same side (LHS or RHS) of the diaphragm. Stage 3: nodes both sides of diaphragm. Stage 4: involvement of extra-nodal sites: liver, bone, lung, and nodes. Prognosis 80% excellent response to treatment and many cured. Prognosis worsens with presence of B symptoms, age > 60, stage III or IV and increased LDH level of activity. Many associated with EBV infection. Lookalikes: need to be separated from Hodgkin disease using Immunomarkers: Ki1 Lymphoma (anaplastic large cell lymphoma) T cell lymphoma T cell rich B cell lymphoma Non Hodgkin Lymphoma (NHL) 70- 80% Characteristics/Classification Commonly extra-nodal: 70-80% The REAL classification system and divides diseases into T cell, B cell and null cell lymphomas. Can be B cell or T cell, low grade (small cell size) or high grade (large cell size). Immunohistochemistry Markers Used CD20 and CD79 B Cell Lymphomas CD3 T Cell lymphomas BCL2 and CD10 Follicular lymphoma CD5 and CD23 Small cell lymphocytic Lymphoma Cyclin D1 Mantle cell lymphoma Diagnostic Steps Immunohistochemistry is not sensitive enough for Dx. Molecular studies are required to show monoclonality e.g. gene rearrangements. Clonality to diagnose malignancy Monoclonal (important) B Cell Lymphomas Ig gene rearrangements. T Cell lymphomas T cell receptor rearrangements. IHC to diagnose type of lymphoma. Ann Arbor Staging is also used here. Comparison Table Most common HL. Thick bands of sclerotic collagen divide the lymph node into nodules. RS or Hodgkin cells. Eosinophils are prominent. Granulomas and necrosis are frequent and may lead to confusion with tuberculosis. The rarest & most aggressive form of HL. Pleomorphic RS cells. Sclerosis may be prominent. HL NHL Incidence Less than NHL More than HL Cell of origin B-cells B or T cells Type of Cell RSC No characteristic cells Age Commonly young adults Older adults L.N spread Contiguously (orderly) Sporadic B-symptoms Common Less common (>20% of patients) Extra-nodal Less common More common Cure Most Some
  • 4. Non-Hodgkin Lymphoma (NHL) contd B cell NH-Lymphomas: B Cell Lymphoma Cell of Origin & Markers Pathogenesis & Presentation Epidemiology & Prognostics Follicular B Cell Lymphoma Centrocyte/ Centroblast BCL2 & CD10. Definition: Small neoplastic B cells form follicle-like nodules. Cause: t(14;18) BCL2. Pathogenesis: Antiapoptotic BCL2 gene on chromosome 18 translocated to chromosome 14 overexpression of anti-apoptotic proteins B cell proliferation. NB: Follicular Lymphoma is BCL2 positive, monoclonal, destroys lymph node architecture and doesnt have tingible body macrophages where as reactive follicular hyperplasia is the opposite. One of the commonest lymphomas: Affects >50 years 60% stage III or IV at presentation. Rarely get cured but indolent (not aggressive) and progressive disease. 70% - 5 year survival. 20% - transform to high grade. Small Cell Lymphocytic Lymphoma Lymphocyte CD5 & CD23 Definition: Chronic lymphocytic leukaemia that has spread to/manifested in the tissues. Presentation: Widespread adenopathy, Splenomegaly, decreased Ig increased infection 5-10% Richters Syndrome high grade transformation (cells become big) Commonly stage III or IV because asymptomatic at presentation. Mantle Cell Lymphoma Mantle cells Cyclin D1 Definition: diffuse replacement of node by malignant/neoplastic mantle B-cells. Cause: t(11;14) Cyclin D1. Pathogenesis: Cyclin D1 gene on chromosome 11 translocated to chromosome 14 inc. cyclin D1 more cells enter G1/S phase increased proliferation. <5% of all lymphomas (rarer): Age distribution: peak 60-70 years. Often high stage at presentation . 20-40% - 5 year survival. Marginal Zone Lymphoma (ex: Maltoma GIT) Marginal zone cells Definition: Extra-nodal lymphomas that are usually low grade. Predisposing Factors: Antigen Challenge. Pathogenesis: associated with and found in chronic inflammatory conditions: GIT HLO in stomach, Thyroid Hashimotos, Salivary gland Sjogrens, Lungs Due to increased cell turnover precipitated by the underlying condition Diffuse Large Cell B Cell Lymphoma Centroblasts Definition: Large mononuclear neoplastic B cells proliferate and can spread to extra-nodal sites. Commonest high grade B cell lymphoma: Aggressive but curable. Lymphoblastic B Cell Lymphoma Lymphoblast Rare (Majority are T cell LBLs); Bone lytic lesions. Many children and young adults Burkitts Lymphoma Lymphoblast, EBV + & activated c-Myc Definition: Type of lymphoblastic lymphoma. Intermediate B cell proliferation. Cause: t(8;14) c-Myc. Pathogenesis: EBV associated, c-Myc translocation from chromosome 8 to 14 present deregulation of oncogenic function increased cell growth. Clinical Presentation: extra-nodal mass in jaw, GIT, gonads in young adults/kids. IHC starry sky appearance on microscopy. African form jaw. Sporadic form abdomen. Rare in Europe. Occurs in children and adolescents. Lymphocyte, Mantle cell, Marginal cell, Lymphoblast, Immunoblast, Centrocyte/Cleaved FCC follicle centre cell Centroblast/Non cleaved FCC Plasma cell large B cells F.C.C. Cleaved & non-cleaved Aka centrocytes/ centroblasts Histiocytes Mantle cells Marginal Cells Plasma cell Lymphocytes L O W G R A D E H I G H G R A D E
  • 5. T cell NH-Lymphomas Low Grade 1. Mycosis Fungoides T cell lymphoma producing scaly, pruritic, well-demarcated skin plaques and patches. In the later stages of the disease, mushroom-shaped tumours develop within the plaque lesions, and ultimately lymphadenopathy and hepatosplenomegaly can develop. Occurs in adults 12 year survival 2. Sezary syndrome Cutaneous (skin) T-cell lymphoma with leukaemic dissemination of mutated T cells (which distinguishes it from mycosis fungoides). It thus becomes a T cell leukaemia and is considered an advanced stage of mycosis fungoides. 3. T cell Chronic Lymphocytic leukaemia (CLL) High Grade 1. Peripheral T CellLymphoma (most high grade are classified as this) 2. Enteropathy associated T CellLymphoma (EATL) It is a complication of celiac disease, occurs in the small bowel and is commoner in those with poor dietary control. 3. T Lymphoblastic Lymphoma Young adults but very rare Rapid enlargement of nodes On histology, large lymphoid cells that react with T lymphocyte markers 4. T Adult T cell leukaemia/lymphoma Rare Japan/Caribbean HTLV1 Virus Hypercalcaemia (PTH) Other Lymphomas 1. Extra-Nodal Lymphoma Lymphomas of mucosa and non-nodal tissue 2. Nasal Lymphoma High grade lymphoma of nose Null of NK cells Common in Asia but uncommon in Europe EBV associated Causes of Lymphoma 1. Antigen challenge: the first encounter between an immunocompetent lymphocyte and an invading antigen. 2. Viruses EBV associated with: Burkitts, Nasal lymphomas, Hodgkins (BNH) 3. Immunodeficiency 4. Radiation 5. Previous chemotherapy Leukaemia vs Lymphoma Summary of Management (for ALL NHLs) Diagnosis Radiologist takes the trucut Painless persistent enlargement of node 賊 B symptoms Loss of normal architecture (not reactive follicular hyperplasia) Monoclonality malignancy (determined by molecular studies of gene rearrangements) Hodgkin or Non Hodgkin Reed Sternberg cell Dx Hodgkins No RS cells Dx Non Hodgkins Small cells (Low Grade) or large cells High Grade) replace node Lymphoid markers are essential to type lymphoma correctly Molecular markers now being increasingly used Grade Rye Grading Stage Ann Arbor Staging CT, PET, BMT Treatment Rituximab B cell (CD20 monoclonal antibody) Chemotherapy Radiotherapy Bone marrow transplant Lymphoma Leukaemia High WCC >20,000 Normal WCC Patchy marrow involvement Extensive marrow replacement Little lymphadenopathy Prominent lymphadenopathy
  • 6. Thymus The thymus arises from the endoderm of 3rd and 4th branchial pouch. It migrates down from the neck to the mediastinum where it houses T cells and produces hormones that allow them to mature further. Thymus gets smaller after birth and is almost completely atrophied in adults. Functions of Thymus Responsible for differentiation and direction of T cells Central role in cell mediated immunity Enlargement of Thymus 1. Myasthenia gravis 80% thymic hyperplasia autoimmune thymitis 80% AChr antibody against myeloid cells 15% get thymoma Treatment Thymectomy 2. Thymomas (epithelial neoplasm of thymus; oma doesnt indicate benign or malignant - can be either) May present with associated diseases: 30% myasthenia gravis Rheumatoid arthritis Sjogrens syndrome Anterior mediastinal mass NB: Prognosis behaviour correlates with grade 3. Lymphomas T cell most are T cell B cell 4. Germ cell tumours 5. Carcinoid tumours Spleen White pulp: lymphoid follicles (Malpighian bodies). Red pulp: venous sinuses & cords (lymphocytes). Weight: 120-150g. Functions of Spleen Splenic Atrophy Physiological old age. Sickle cell disease sickle cells get trapped in blood vessels that supply the spleen spleen becomes infarcted in areas heals by fibrosis small spleen. Coeliac disease idiopathic. Splenomegaly Splenomegaly causes: hypersplenism which is the enlargement of spleen for any reason causing destruction of blood cells and consequently a reduction in these cells in the peripheral blood anaemia, thrombocytopenia & leukopenia. Causes of splenomegaly include: 1. Congestive Cirrhosis of liver portal vein thrombus inc. pressure on the splenic vein. 2. Collagen Vascular Diseases (Autoimmune Disorders) Rheumatoid arthritis Systematic Lupus Erythematosus (SLE) Polyarteritis Nodosa (PAN) 3. Storage Disorders Hyperlipidaemias Lipid storage disorders Gauchers disease Neiman Picks Disease 4. Infections Malaria Leishmaniasis (protozoal) Infectious mononucleosis spontaneous rupture Brucellosis S.B.E subacute bacterial endocarditis Endocarditis septic emboli from endocarditis go to the spleen abscess. NB: Splenomegaly due to infection is more seen in children and when seen in adults more due to viral than bacterial infection (esp. infectious mono). 5. Amyloidosis 6. Disorders of blood & marrow Leukaemias and Lymphomas Haemolytic anaemia red cells broken down by histiocytes & macrophages in spleen gets bigger. Myelofibrosis myelo = fibrosis; spleen cant produce red cells & blood components so function taken over by the liver. Myeloproliferative disorders Myeloproliferative Cell Neoplasms/Disorders Clonal neoplastic proliferation of stem cells, affecting all cell lines of the bone marrow with variable clinical presentation and variable prognosis (excluding acute leukaemia). Diagnosis Clinical presentation (3 conditions) FBC BMT and BM aspirate Pathogenesis activating mutation in gene coding for tyrosine kinases. Characteristics 1. Arise from common stem cell cases with intermediate features 2. Frequent evolution of 1 type to another 3. Invariable involvement of more than 1 cell line due to an abnormal clone with increased sensitivity to growth factors. 4. Occur in people > 50 years 5. Splenomegaly 6. Mutation of the tyrosine kinase JAK2 (Janus kinase 2 gene). Causes increased sensitivity to intercellular signalling from growth factors. Presentation Concepts Excess of one cell type may cause a decrease of other cell types High content of one cell type may cause symptoms Anaemia and infection Bleeding/thrombosis Hyperviscosity syndrome Tumour Markers in Nodes & Spleen, Thymus and Bone Marrow 1. Haemopoiesis 2. Antibody formation 3. Cell sequestration 4. Cell destruction 5. Iron metabolism 6. Phagocytosis
  • 7. 1. Chronic granulocytic/myeloid leukaemia (commonest) 2. Myelofibrosis 60% JAK2 3. Polycythaemia rubra vera (RBC) 90% JAK2 4. Essential thrombocythaemia/ Thrombocytosis (Platelets) 60% JAK2 1) Chronic Myeloid/Granulocytic Leukaemia (CML/CGL) Neoplastic proliferation of stem cells that differentiate into mature myeloid cells, especially granulocytes (characteristically basophils). Characterised by Philadelphia fusion chromosome t(9;22) which results in a BCR-ABL fusion protein with increased tyrosine kinase activity. This is also an MPD (Myeloproliferative Disorder). Presentation Marrow replacement with/without failure anaemia, bleeding, bruising, infection. Marked leucocytosis 50,000 abnormal. Marked hepatosplenomegaly. Weight loss. Epidemiology Middle age 40-60 years. Diagnosis 1. WCC above 100,000 instead of 7,000 2. Increased blasts in the peripheral blood too many being released (shouldnt normally be there) can become a crisis. 3. PHI chromosome 22.9 (used to) 4. BCR-ABL rearrangement diagnostic of CML. 2) Myelofibrosis - 60% JAK2 Neoplastic proliferation of mature myeloid cells especially megakaryocytes. Primary Myelofibrosis: Megakaryocytes produce excess platelet-derived growth factor (PDGF) marrow fibrosis. Secondary Myelofibrosis: Metastases to marrow Radiotherapy to marrow Cytotoxic drugs Presentation Fibrosis reduces marrows haematopoietic capability migration of erythroid precursors to spleen & liver extramedullary haematopoiesis hepato- splenomegaly & poikilocytosis (abnormal RBCs). Loss of marrow cells Terminal blast crisis Life expectancy - 7 years Treatment Supportive Marrow stimulation +/- Splenectomy (cells being produced are being destroyed in the spleen remove it to salvage the few being produced) 3) Essential thrombocythemia/thrombocytosis (platelets) - 60% JAK2 Neoplastic proliferation of mature myeloid cells especially platelets. Presentation: Increased platelet count: 1 million; (normal: 350,000) Bleeding/thrombotic abnormalities Enlarged spleen Enlarged liver Treatment Hydroxyurea 4) Polycythaemia Rubra Vera 90% JAK2 Neoplastic proliferation of mature myeloid cells especially RBCs increased red cell volume. Primary Polycythaemia: Malignancy of red blood cells High Hb and Haematocrit Secondary Polycythaemia: High altitudes Congenital Heart Disease Tumours (e.g. renal cell carcinoma ) Erythropoietin production (e.g. renal carcinoma) Presentation Red face (jumping jacks JAK red face) Thrombotic and haemorrhagic events Increased Hb Enlarged spleen Marrow erythropoiesis Treatment 1. 1st line: Phlebotomies (older patients): remove excess cells by removing blood. 2. 2nd line: Hydroxyurea (myelosuppressive treatment) 3. Exclude secondary causes 4. Radiotherapy with 32P isotope. Prognosis: 50%= 12 year survival (usually terminal with blast crisis).
  • 8. Investigations FBC Leukocyte ALK phosphatase (LAP) differentiates CML from other causes of leucocytosis BCR-Abl gene rearrangement Uric acid JAK2 BMT bone marrow trephine (always have to do this) Myelodysplastic Syndrome Smouldering neoplastic proliferation of stem cells of bone marrow, majority terminate after 1-3 years in leukaemia (more aggressive) occurs in younger ppl A pre-leukaemic disorder Usually low peripheral cell count with hypercellular marrow Often in Myeloproliferative cell neoplasms/disorders you have a high peripheral cell count and hypercellular marrow Associated with a variety of chromosomal abnormalities Diagnosis based on clinical haematological and bone trephine May follow previous chemotherapy treatment or may occur de novo Classification of myelodysplasia depends on which cell line shows the dominant abnormality. There are 8 different types These are difficult to diagnose and require cytogenetic studies and correlation between the marrow aspirate and the FBC etc Some will progress into Leukaemia within 2 years