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• By the end of this session you should be able to:– Describe the components of the lymphoid
system– List the disorders of the lymphoid system– List the causes of leukopenia and leukocytosis– Be able to process a lymph node biopsy– Understand and pathology of common
infections involving lymph nodes
Contents
• Introduction
• Processing lymph node biopsy
• Leukopenia and Leukocytosis
• Infectious mononucleosis
• Acute and chronic lymphadinitis
• Cat-scratch disease
• Granulomatous inflammation
Basics
• What is the lymphoid system?– Components, function
• Consists of the lymph with the lymphatic channels and vessels, lymph nodes, thymus, spleen, and the visceral lymphoid tissue (GI, respiratory tract etc.)
• Function: Immune system.
Types of lymphocytes
• T cell: – Cellular immunity– Produced in the bone marrow, mature in the
thymus and released in the peripheral circulation
– 2 subsets: T helper, and T cytotoxic– Th1, Th2
Types of lymphocytes
• B cells:– Humoral immunity (antibody production)– Produced in the bone marrow, released to the
lymphoid organs. When activated matures to form plasma cells
List of Causes (or Disorders)
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Symptoms and Signs
• Primary, Secondary, Non specific• Anatomical and Functional• Complications of the disease process
– Eg. Features of lymphoma• Lymphadenopathy, fever, night sweat, wt. Loss• Mass effect, vascular obstruction, eg. Superior vena cava
syndorme.• Suppressed immunity.
– Eg. Features of chronic liver disease.
Anatomy of the Lymph Node
• 3 major zones:– Cortex:
• B-cells, Follicles, Mantle cells, Marginal zones, secondary follicles, germinal centers
– Paracortex:• T-cells, interdigitating dendritic cells, post capillary
venules
– Medulla:• Lymph sinuses, veins, arteries, plasma cells, B-cells
mainly
Cells in the Lymph Node• T-cells:
– Bone marrow---Thymus---Paracortical area of LN– Cellular immunity
• B-cells:– Bone marrow, gut lymphoid tissue– Cortex and Medulla of LN– Humoral immunity
• Natural Killer cells– Do not mark as B or T– No specific distribution
• Others: Histiocytes, follicular and interdigitation dedritic cells, plasma cells, neutrophils, endothelial cells
Case
• 50 year old man with Diffuse large B cell lymphoma.
• He received 4 cycles of chemotherapy.
• Now he has neutropenia.
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Non-Neoplastic disorders
• Leukopenia– Any type of the white blood cell– Causes: congenital, acquired – Neutropenia
Non-Neoplastic disorders
• Leukopenia– Any type of the white blood cell– Causes: congenital, acquired – Neutropenia
• Inadequate or ineffective hematopoiesis
• Destruction of neutrophils
• Clinical presentation: malaise, fever, infections, oral ulcers
Reactive Leukocytosis
• Neutrophilic leukocytosis
• Lymphocytosis
• Eosinophilic leukocytosis
• Basophilic leukocytosis
• Monocytosis
Case
• 21 year old female with history of bilateral cercical lymphadenopathy for 2 months.
• The illness started with sore throat and few days of fever.
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Infectious Mononucleosis
• EBV infection• Acute self-limiting• Adolescents and young adults1. Fever, sore throat, generalized
lymphadenopathy2. Lymphocytosis with atypical lymphocytes
on smear3. Positive serology for EBV
Infectious Mononucleosis
• Route of infection: saliva?• Types of infection: Productive , latent• Polyclonal B cell proliferation• Morphology:
– Peripheral blood, Lymph nodes, Spleen, Liver
• EBV in immunosuppresed individual• EBV in X-linked lymphoproliferative
syndorme
Case
• 10 year-old boy with right axillary lymphadenopathy for 2 weeks
• He had forearm injury with skin infection.
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Case
• 50 year old lady with Rheumatoid arthritis for several years
• She has generalized lymphadenopathy.
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Reactive lymphadenitis
• Acute non-specific lymphadenitis– infections– Local or generalized– Morphology
• Chronic non-specific lymphadenitis– Follicular hyperplasia– Paracortical lymphoid hyperplasia– Siuns histiocytosis
Case
• 15 year old boy with right cervical lymphadenopathy for 6 weeks
• No previous history of illness
• Lymph node biopsy shows necrotizing lymphadenitis
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Cat-Scratch Disease
• Infection: Bartonella henselae
• Acute self-limiting
• Children
• Regional lymphadenopathy: axilla, neck
• Regress over 2-4 months
• Morphology
Case
• 28 year old Indian male.
• Has generalized lymphadenopathy, more prominent in the neck bilaterally.
• Lymph node biopsy shows granulomatous inflammation
List of Causes
• Primary vs Secondary• Congenital/Genetic vs Acquired• The Acquired: Non-neoplastic, Neoplastic• Non-neoplastic: Inflammatory, Idiopathic• Inflammatory: Infection, Drugs, Toxins,
Metabolic, Immune– Eg. Causes of hepatitis, heart failure,
lymphadenopathy
Granulomatous inflammation
• Types: necrotizing , non-necrotizing
• Causes: infectious, non- infectious
• Infections: bacterial (T.B), fungal (Histoplasma), Parasitic (Schistosoma), Viral (less likely)
• Non-infectious: Foreign body, immune (sarcoidosis), idiopathic