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Assignment No 1 pathology II 16-09-13

“Enumerate the Anatomy and Physiology of Lymphatic system. Discuss the pathological features with reference to the Inflammation and Infection in the Lymphatic System”

“Anatomy & Physiology of Lymphatic System”

Consists of lymph, lymph vessels, lymph nodes, lymphatic tissue, and 4 organs

Tonsils Spleen Thymus Gland Peyer’s Patches

Works in conjunction with the circulatory system to remove wastes and excess fluids from the tissues.

Lymphatic system Function:

Drain protein-containing fluid from tissue spaces (primary function).o Interstitial fluid can cause edema

Transport fats from the digestive systemo Via lacteals in the villi of the small intestine

Produce lymphocyteso A type of leukocyte

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Develop immunitieso Antibodies

What is Lymph?A thin, watery fluid composed of intercellular or interstitial fluid, which forms when plasma diffuses into tissue spacesComposed of water, digested nutrients, salts, hormones, oxygen, carbon dioxide, lymphocytes, and metabolic wastes such as ureaWhen this fluid enters the lymphatic system, it is known as lymph.

Lymphatic Vessels:Located throughout body in almost all of the tissues that have blood vessels Small, open-ended lymph vessels act like drainpipes and are called lymphatic capillariesLymphatic capillaries pick up lymph at tissues throughout body Capillaries then join together to form larger lymphatic vessels, which pass through lymph nodes.Contractions of skeletal muscles against lymph vessels cause the lymph to flow through the vessels.Lymphatic vessels also have valves that keep lymph flowing one-wayDrains lymph into blood via thoracic duct (main) or right lymphatic duct.

Lymph Nodes:

Popularly called “ glands”. Located all over body, usually in groups or clusters; Small, round or oval masses ranging in size from that of a pinhead to an almond.Filter lymph and remove impurities such as carbon, cancer cells, pathogens, and dead blood cells, Produce lymphocytes and antibodies

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Lymphatic Tissues:

Tonsils – masses of lymphatic tissue that filter interstitial fluid; there are 3 pairsPalatine tonsils: located on each side of the soft palatePharyngeal tonsils: (also called adenoids) located in the nasopharynxLingual tonsils: located on the back of the tongueT&A not performed as often due to better understanding of importance of these tissues.

Spleen

An organ located beneath the left side of the diaphragm and in back of the upper part of the stomach

Produces leukocytes and antibodies Destroys old erythrocytes Stores erythrocytes to release into bloodstream if excessive

bleeding occurs Releases hemoglobin to be recycled Filters metabolites and wastes from body tissues

Thymus:

A mass of lymph tissue located in center of upper chest Atrophies after puberty and is replaced by fat and connective

tissue During early life, it produces antibodies and manufactures

lymphocytes to fight infection Its function is taken over by the lymph nodes

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Immunity:

Ability of body to resist infection from pathogenso Active – response from antigen or vaccinationo Passive – via placenta, breast milk, or antivenom

Antigenso Foreign proteins that gain access to our bodies via

circulatory, digestive, respiratory, urinary and reproductive systems

o Cause immune system to produce high molecular weight proteins called antibodies

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Antibodies or Immunoglobulinso Bind with specific antigenso Binding causes agglutinationo Leukocytes eat agglutinate by phagocytosis

___“Pathological Features”___

Hodgkin lymphoma:

Hodgkin lymphoma is a less common nodal disease whose diagnosis is based on the detection of a characteristic cell, the Reed Sternberg cell, in the appropriate histologic settingThere are several (five) histologic subtypes, but prognosis is based primarily on extent of disease.Hodgkin lymphoma is a more curable disease than non-Hodgkin lymphomasNow watch me confuse this relatively straightforward information with the details.

Clinical Features:

Enlarging mass(es), typically painless, at sites of nodal tissueCompression, infiltration of hollow organs

Pain, obstruction, perforation Interference with normal organ function- Solid organ infiltration- kidneys, liver, bone marrow

Systemic symptoms: Fever, Night sweats ,Weight lossIf marrow infiltrated, can have leukemic componentNHL 2:

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Recapitulate the biology and immunophenotype of normal cell counterpart

Several cytologically and immunologically recognizable stages of normal lymphoid maturation --> several subtypes of lymphoma

Clonal malignancies, derived from a single cell that has undergone a malignant transformation, mutation

Best initially conceptualized as two major clinical typeso Indolent lymphomaso Aggressive lymphomas

Indolent Lymphomas:

Lymphomas frozen at stages not normally replicating, but may be circulating

Diseases of slow accumulation, due to defective apoptosis Often widespread at diagnosis Prolonged natural history, median survivals >5 years Will usually respond to chemo- or radiation therapy Will usually relapse, but respond to same or alternative tx Currently incurable unless

o Localized disease or o Marrow ablation with some type of stem cell transplant

Classification of indolent lymphomas- later

Aggressive lymphomas:

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Lymphomas frozen at stages characterized by replication and accelerated growth

Diseases of defective cell cycle control More often localized at presentation than indolent lymphomas More often extranodal Despite short natural history, curable disease in some with

aggressive therapyo Approximately 30-40% of adultso 50-80% children

All childhood lymphomas of this type

Brukkit’s Lymphoma:

Clinical 3% lymphomas Disease of adults and children- median age 31 Initially recognized in Africa by Thomas Burkitt Association with Epstein Barr virus infection Localization in jaw In US, usually presents in ileocecal region of children 1/3 of all childhood lymphomas Earlier eras, very aggressive and rapidly fatal Now, ~70-80% children curable 40% of adults

Pathology Benign equivalent is replicating small noncleaved cell of

germinal center: Diffuse infiltration of lymph node Very high mitotic rate, lot of ineffective proliferation; Attracts macrophages to phagocytize> starry sky pattern at

low power

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Cytology: round nucleus, smaller than that of reactive macrophage

Vesicular chromatin and 2-5 nucleoli Immunophenotype:

o Positive: Monoclonal light chain, CD19, CD10o Negative: CD5

T cell lymphomas – Precursor T:

Pathology Benign equivalent immature T cells of thymus Histology: Diffuse infiltration of thymus/adjacent lymph

nodes Cytology: “Blast cells” of intermediate size with oval to

“convoluted” nuclear profiles, fine chromatin and 0-1 nucleolus

Again need immunology to distinguish from pre-B Predominantly leukemic/disseminated

T-cell prolymphocytic leukemia T-cell large granular lymphocytic (LGL) leukemia NK cell leukemia Adult T-cell leukemia/lymphoma

Predominantly nodal Angioimmunoblastic T-cell lymphoma Peripheral T-cell lymphoma unspecified Anaplastic large cell lymphoma, T/null-cell

Predominantly extranodal Mycosis fungoides Sezary syndrome

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Primary cutaneous CD30+ T-cell lymphoproliferative disorders

Subcutaneous panniculitis-like T-cell lymphoma NK/T cell lymphoma, nasal and nasal-type Enteropathy-type intestinal T-cell lymphoma Hepatosplenic T-cell lymphoma

Hodgkin’s Lymphoma:

Less common than NHL; ~ 10,000 cases per year Age incidence bimodal, with one peak in late adolescence,

young adulthood, second peak beginning in sixth decade Bimodal curve shifts to younger ages in poorer countries Unlike NHL, HL diagnosed by the presence of a minor cellular

component, the Reed-Sternberg cell, found in the appropriate microscopic cellular background

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To: Sir MubbenBy: Tahir RamzanCMS: 3855