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47 Cards in this Set
- Front
- Back
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Primary (central) lymphoid tissues?
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Contain B or T-lymphoid precursors and provide their maturation to fxnally mature, but naive B or T cells.
1. Bone Marrow -- origin and differentiation of B-lymphocytes 2. Thymus -- origin and differentiation of T-lymphocytes |
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Secondary (peripheral) lymphoid tissues?
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Sites where Ag specific rxns of mature B and T lymphocytes occur
1. lymph nodes 2. spleen 3. MALT -- naso and oropharynx --> Waldryer's ring: adenoid and tonsils -- GI tract --> Peyer's patches |
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Two major phases of differentiation in T and B cell systems?
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1. Early Ag INDEPENDENT phase
-- occurs in primary organs, BM and thymus -- lymphoid precursors (blasts) give rise to mature cells capable of recognizing Ag but are "naive" 2. Later Ag-DEPENDENT phase -- exposure to Ag -- naive lymphocytes undergo "blast transformation" (change in appearance and growth characteristics) -- become large, proliferating cells that give rise to Ag-specific memory B and T cells and Ab producing plasma cells |
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B and T cell systems have what two major types of cells?
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1. precursor lymphoblasts (primary lymphoid tissue)
2. mature B and T cells -- can be naive or memory cells |
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What is the third type of lymphoid cell (other than B and T)?
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Natural killer (NK) cells
-- can kill targets w/o prior sensitization and w/o MHC restriction Appear to derive from common progenitor w/ T cells Cytoplasm contains azurophilic granules, called larage granular lymphocytes (LGL) |
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Quantitative lymphocytic disorders can be due to...?
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DEFICIENCY
1. congenital immunodeficiency 2. HIV 3. cytotoxic PROLIFERATION 1. Blood: lymphocytosis -- reactive -- neoplastic --> lymphocytic leukemia 2. Lymphoid tissues: lymphadenopathy -- reactive -- neoplastic --> malignant lymphoma |
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What is the most frequent lymphocytic disorder?
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Lymphocytosis -- INCREASE in lymphocyte number
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Define lymphocytosis.
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An increase in the ABSOLUTE lymphocyte count in the peripheral blood (CBC).
-- should be distinguished from relative lymphocytosis due to increase in PMNs Image of normal vs. absolute vs. relative (185) |
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Causes of lymphocytosis?
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REACTIVE
-- infectious mono -- IM-like syndromes: CMV, acute HIV, Herpesvirus 6, Adenovirus -- Viral hepatitis -- Bordatella pertussis NEOPLASTIC -- Acute lymphocytic leukemia (ALL) -- Chronic lymphocytic leukemia (CLL) -- Hairy cell leukemia -- lymphoma (some lymphomas have cells that circ in peripheral blood) |
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Compare reactive vs. neoplastic lymphocytosis.
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REACTIVE
-- Transient -- WBC <30K/mm3 -- heterogeneous -- polyclonal NEOPLASTIC -- sustained -- WBC >30K/mm3 -- monotonous (monomorphic) -- clonal |
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What is infectious mononucleosis?
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A benign, self-limiting disorder caused by Epstein Barr virus (EBV)
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Clinical presentation of infectious mono?
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Typically btwn 10-25y.o.
Fever, malaise Sore throat (pharyngitis) Lymphadenopathy and splenomegaly Jaundice |
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Pathogenesis of infectious mono?
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1. Route of transmission: intimate contact w/ saliva (kissing) from previously infected person
2. EBV infects B lymphocytes -- binds mbrn CD21 -- in the oropharynx 3. Virus disseminates to lymphoid tissues 4. Provokes and intense immune response and symptoms |
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What are the two types of mono infections?
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1. Lytic (productive) infection w/ release of virus, then reinfection
2. Latent infection (incorporated into genome) -- leads to polyclonal B cell prolif |
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How is mono infection controlled?
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1. CTL (CD8+) and NK cells --> the reactive atypical lymphocytes in peripheral blood
2. EBV specific or non-EBV specific (heterophil) antibodies |
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Pathology of mono?
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Peripheral blood smear:
-- atypical lymphocytosis Lymph node histology: -- predominant paracortical hyperplasia |
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How to confirm mono dx?
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1. Monospot
-- heterophile Ab test 2. Specific Ab for EBV Ag -- EA -- EBNA -- VCA |
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Clinical course for mono?
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self-limited
resolves in 4-6wks |
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What is the differential for lymphocytosis?
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1. Benign
-- viral infections - mono, CMV, hep -- Bordatella pertussis 2. Malignant -- Acute lymphoblastic leukemia -- Chronic lymphocytic leukemia -- lymphoma |
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What is chronic lymphocytic leukemia (CLL)?
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a chronic neoplastic (clonal) lymphoproliferative disorder of small mature B-lymphocytes
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Clinical presentation of CLL?
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-- most common leukemia of adults, middle aged, and elderly
-- often asymptomatic -- weakness, easy fatigue, weightloss -- generalized lymphadenopathy (50-60%) -- splenomegaly and/or hepatomegaly |
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Lab findings in CLL?
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1. HALLMARK:
-- sustained peripheral blood lymphocytosis 2. Morphologically small, monotonous, mature lymphocytes w/ condensed (hyperchromatic) chromatin; smudged cells 3. May have anemia, thrombocytopenia (high clinical stages) 4. Hypogammaglobilinemia w/ increased susceptibility to infection |
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Differential diagnosis of lymphocytosis?
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BENIGN
1. reactive lymphocytosis MALIGNANT 1. Mature -- Hairy cell leukemia -- Lymphoma 2. Immature -- ALL |
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BM aspirate and biopsy in CLL?
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1. infiltrate of small lymphocytes
2. patterns: interstitial, nodular, and diffuse |
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Lab tests to confirm dx of CLL?
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1. Immunophenotyping
-- clonal mature B lymphocytes -- monoclonal B-cells (expression of monoclonal kappa or lambda light chain, CD20, CD19) -- dim surface Ig -- CD5+ -- CD23+ 2. Cytogenetics -- trisomy 12q -- deletions of 13q12-14, 11q, and 17p |
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What will CLL lymph node biopsy look like?
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1. diffuse effacement by an infiltrate of small lymphocytes
2. pseudonodule "growth centers" of prolymphocytes and paraimmunoblasts 3. CLL and/or SLL |
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Compare CLL with SLL (small lymphocytic lymphoma).
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They are morphologically, genotypically, and phenotypically identical
Differ in clinical distribution: -- CLL --> bone marrow and blood; circulate and infiltrate LN, liver, spleen -- SLL --> predominantly involves LN but cells spread to BM and blood Some pts may present later in disease and have involvement of all sites, prompting term CLL/SLL |
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Clinical course of CLL?
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1. indolent but UNCURABLE
2. infections 3. Richter transformation to large cell lymphoma -- ~10% manifest as rapidly enlarging mass in LN or spleen 4. Prolymphocytic transformation (15-30%) -- worsening cytopenias -- large cells w/ prominent nucleoli (prolymphocytes) in blood -- increasing splenomegaly |
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What is Hairy cell leukemia (HCL)?
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a clonal lymphoproliferative disorder of mature B cells
-- represents 2% of all leukemias |
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HCL clinical presentation?
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Adults (mean of 50)
More common in men Splenomegaly -- often massive Often symptomatic: -- fatigue -- recurrent infection -- abdominal discomfort |
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HCL peripheral blood smear findings?
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1. pancytopenia
2. neutropenia 3. monocytopenia 4. circulating abnormal lymphocytes "hairy cells" |
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Lab tests to confirm dx of HCL?
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1. Tartrate Resistant Acid Phosphatase (TRAP) Stain
-- TRAP + 2. Immunophenotyping -- Clonal mature B-lymphocytes -- Monoclonal B cells -- strong surface Ig -- CD11c+, CD25+, CD103+ |
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HCL BM biopsy will show...?
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Fibrosis
-- usually leads to "dry tap" on attempted BM aspiration Interstitial infiltration by hairy cells w/ pale to clear cytoplasm - "fried egg" appearance |
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HCL splenectomy will show?
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infiltration of red pulp forming "blood lakes"
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Features distinguishing HCL from CLL?
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1. splenomegaly but NO lymphadenopathy
2. pancytopenia NOT leukocytosis 3. hairy cells NOT small lymphocytes 4. Bone marrow NOT aspirable 5. TRAP(+) 6. Immunophenotype |
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Clinical course of HCL?
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Long lasting remissions w/ newer chemo agents
-- 2CDA, deoxycoformycin, alpha-interferon |
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What is lymphadeopathy?
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Enlarged LN due to benign or neoplastic disorders
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What type of neoplastic disorders can cause lymphadenopathy?
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metastatic malignancies
-- carcinoma neoplasms primary to lymphoid system -- lymphoma |
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Cellular composition of the normal lymph node?
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B LYMPHOCYTES
1. mantle cells -- naive B cells 2. follicle center cells -- centroblasts - large noncleaved cells -- centrocytes - small cleaved cells 3. marginal zone B cells (memory B) -- normally only seen as a well-defined compartment in the spleen and mesenteric lymph nodes T LYMPHOCYTES -- paracortex PLASMA CELLS -- medulla HISTIOCYTES -- sinuses |
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Causes of reactive lymph node hyperplasia?
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Infections: bacterial, protozoal, fungal
Autoimmune disease Drugs Vaccination Others |
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Patterns of reactive lymph node hyperplasia?
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1. follicular
2. paracortical 3. mixed (follicular and paracortical) 4. sinusoidal |
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Acute lymphadenitis?
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CAUSES:
1. bacterial infection 2. viral infection MORPHOLOGY 1. follicular hyperplasia -- germinal centers -- tingible body macrophages 2. suppuration |
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Chronic lymphadenitis that causes follicular hyperplasia?
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RA
Autoimmune D/O's Toxoplasmosis Syphilis Viral infection (early HIV) |
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Chronic lymphadenitis that causes paracortical hyperplasia?
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Dermatopathic lymphadenopathy
Mono Drug HSN rxn - Dilantin SLE |
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Chronic lymphadenitis that causes sinus histiocytosis?
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Rosai-Dorfman disease
-- sinus histiocytosis w/ massive lymphadenopathy |
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Causes of chronic granulomatous lymphadenitis?
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caseating granulomas
-- mycobacterial -- fungal suppurative granulomas -- cat scratch disease |
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Differential for lymphoid hyperplasia?
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1. Distinguish from lymphoma
-- preservation of architecture -- heterogeneous cell population -- polyclonal -- usually self-limited 2. Identify etiologic agent |
