Lecture 29 Pathology of Non-Neoplastic disorders of lymph node PDF

American University of Barbados Hematology WBC DISORDERS Pathology of Non-Neoplastic disorders of lymph node (Intended Learning Outcomes) By the end of this lesson students will be able to 1 - List th...

American University of Barbados Hematology WBC DISORDERS Pathology of Non-Neoplastic disorders of lymph node (Intended Learning Outcomes) By the end of this lesson students will be able to 1 - List the causes & types of reactive lymphadenitis 2 - Describe the morphology of reactive lymphadenitis 2.2 - 30.3 - Analyze clinico-morpho-pathological features of various common lymphadenitis Prof. Sylvester Lazarus Dept of Pathology Lymph node anatomy  NORMAL LYMPHNODE Refer to Robbins basic pathology. Edited by Vinay Kumar, Abul K. Abbas, Jon C. Aster – 9th Edition. Elsevier Publication – Page No:  Reactive Lymphadenitis Lymph nodes are defensive barriers against infections and non-microbial inflammatory stimuli which activate the immune cells residing in it. Lymphadenitis : Inflammatory reaction to inflammatory stimuli by both microbial and non- microbial agents Lymphadenopathy : Enlargements of the lymph nodes due to the immune response against antigens Reactive lymphadenitis It can be Acute or Chronic, in most cases it will be Acute non-specific & Chronic non-specific. Acute non-specific lymphadenitis, Isolated (Local infection) or generalized (systemic infections) Chronic non-specific lymphadenitis, can assume one of the three patterns 1. Follicular Hyperplasia 2. Paracortical Hyperplasia 3. Sinus histiocytosis Refer to Robbins basic pathology. Edited by Vinay Kumar, Abul K. Abbas, Jon C. Aster – 9th Edition. Elsevier Publication – Page No: 428 & 427  Acute non- Specific Lymphadenitis These forms of the lymphadenitis are isolated, to a group of nodes draining Local infection or generalized, as in systemic infection or inflammatory conditions. Examples of Infection and node involved - teeth and tonsils - Cervical nodes - the extremities - Axillary and inguinal nodes - the appendix - mesenteric nodes Morphology : Gross : swollen, gray-red, and engorged. Histopathological feature : - Formation of Germinal centers within the follicles by activated B cells - In pyogenic infections, neutrophils are seen around the follicles and within lymphoid sinuses - Sever infection causes the center of the follicle to undergo necrosis, which leads to abscess Clinical features: - Tenderness and fluctuation if the abscess formation is extensive - Overlying skin becomes red and may develop sinuses - If infection is controlled the nodes return to resting appearance or if damaged undergo scarring Refer to Robbins basic pathology. Edited by Vinay Kumar, Abul K. Abbas, Jon C. Aster – 9th Edition. Elsevier Publication – Page No: 428  Chronic non-specific lymphadenitis FOLLICULAR HYPERPLASIA: al -This pattern of lymph node is cause by activated B cell, in response to the stimuli by infection or inflammatory reaction -This activated B cells migrate into the follicles and create a follicular reaction ( Germinal center) Morphology : - Large oblong germinal centers, it is called secondary follicles - (Centrobalsts – Light Zone and Centrocytes – Dark zone) - Mantel zone, color of naïve b-cells surrounding follicles. Varying sizes of germinal centers - Tingible body macrophages, which contain nuclear debris Mantel zone Germinal center Tingible body macrophages  Chronic non-specific lymphadenitis FOLLICULAR HYPERPLASIA: al - Tingible body macrophages, which contain nuclear debris Mantel zone Germinal center Tingible body macrophages Varying sizes of germinal centers  Chronic non-specific lymphadenitis FOLLICULAR HYPERPLASIA: al 1. Rheumatoid arthritis Varying sizes of germinal centers 2. Toxoplasmosis 3. Early stages of HIV infection Follicular hyperplasia is morphologically similar to Follicular lymphoma, features favoring reactive hyperplasia are 1. Preservation of lymphnode architecture 2. Variation in sizes of the follicles 3. Presence of frequent mitotic figures  Chronic non-specific lymphadenitis PARACORTICAL HYPERPLASIA -It is caused by the stimuli which trigger of T cells immune response. -Activated T cells are three or four times larger than B-cells ( Immunoblast) -In exuberant reaction T cell efface the B cell follicle, in such cases special methods such as immunohistochemical staining are need to exclude neoplasms Clinical example : Infectious mononucleosis, vaccination, drug induced ( Phenytoin)  Chronic non-specific lymphadenitis SINUS HISTIOCYTOSIS - It is also called reticular hyperplasia, because of increase in number an size of the lymphatic sinusoids - Although it is non-specific, it is prominent in lymph nodes draining cancer such as carcinoma of breast - There is the distension of lymphoid sinus because of marked hypertrophy of lining lymphatic endothelial cells - Macrophages are greatly increased in number  Reactive lymph node Benign vs. malignant Reactive lymph node with Plasmacytoid Monocytes  Reactive lymphadenitis CAT-SCRATCH DISEASE: A self-limited lymphadenitis, primarily in children younger than 18 years of age Causative organism – Bartonella henselae MORPHOLOGY: - Irregular Stellate Like Central Necrotizing Granuloma - Histocytes, Neutrophils, Occasional Eosinophils - Regional Lymph Node Show Follicular Hyperplasia Clinical manifestation Nodal enlargement appears approximately 2 weeks after a feline scratch or after a splinter or thorn injury An inflammatory nodule, vesicle sometimes visible at the site of the skin injury Lymph node enlargement regresses over a period of 2 to 4 months. Complications: Encephalitis or osteomyelitis may develop Refer to Robbins basic pathology. Edited by Vinay Kumar, Abul K. Abbas, Jon C. Aster – 9th Edition. Elsevier Publication – Page No: 428 Lymphadenopathy  Lymphadenopathy Etiology: Most common cause overall is benign reaction to infection Most common malignant cause is metastatic carcinoma Could be also immunological diseases like SLE, and still disease. Drugs hypersensitivity