The **lymph node** is a small, bean-shaped organ of the lymphatic system that plays a crucial role in immune surveillance and response. Structurally, it is composed of a cortex, paracortex, and medulla, each housing specific immune cells like lymphocytes and macrophages. **Lymphadenopathy** refers to the abnormal enlargement of lymph nodes, often due to infection, autoimmune disease, or malignancy. **Lymphadenitis** is the inflammation of lymph nodes, commonly resulting from bacterial or viral infections. **Lymphoid neoplasms** are cancers arising from lymphoid tissues, including **Non-Hodgkin lymphoma (NHL)** and **Hodgkin lymphoma (HL)**. NHL represents a diverse group of lymphoid malignancies with variable prognosis, while HL is characterized by the presence of Reed-Sternberg cells and often follows a more predictable clinical course. **Metastatic carcinoma** involves the spread of malignant epithelial cells from a primary tumor to the lymph nodes, indicating disease progression and often affecting prognosis and treatment strategies.

1. LYMPH NODE PATHOLOGY
Dr. Sonia. J
Junior Resident
Department Of
Pathology
KMCT Medical College

2. CHAPTER OUTLINE
• Structure of lymph node
• Lymphadenopathy
• Lymphadenitis
• Lymphoid neoplasms
• Non-Hodgkin lymphoma
• Hodgkin lymphoma
• Metastatic carcinoma

3. STRUCTURE OF LYMPH NODE
• Capsule, cortex, paracortex, medulla
• Lymphatic vessels: afferent and efferent
• Cellular components: lymphocytes, macrophages,
dendritic cells

4. CAUSES
• Infectious causes
• Bacterial: Tuberculosis, staphylococcal infections
• Viral: Epstein-Barr virus (EBV), HIV, Cytomegalovirus (CMV)
• Fungal or parasitic infections (e.g., histoplasmosis)
• Malignancies
• Primary lymphoid neoplasms: e.g., lymphoma (Hodgkin or Non-Hodgkin)
• Secondary (metastatic) carcinomas: from breast, lung, gastrointestinal tract, etc.
• Immune or autoimmune disorders
• Rheumatoid arthritis
• Systemic lupus erythematosus (SLE)
• Sarcoidosis
• Miscellaneous
• Drug reactions (e.g., phenytoin)
• Storage diseases

5. TYPES
1) Localized lymphadenopathy
• Involvement of a single group of lymph nodes.
• Often due to local infections (e.g., bacterial
infection in throat → cervical nodes).
2) Generalized lymphadenopathy
• Involvement of two or more non-contiguous
regions.
• Suggestive of systemic diseases such as viral
infections, autoimmune conditions, or
malignancies.

6. CLINICAL SIGNIFICANCE
• Important diagnostic clue in many conditions.
• Size, consistency, tenderness, fixation, and mobility
help in clinical assessment:
• Soft, tender, mobile → more likely infectious.
• Firm, rubbery, non-tender → suggestive of
lymphoma.
• Hard, fixed → often indicates metastatic cancer.
• May require biopsy or fine-needle aspiration (FNA)
for definitive diagnosis.

7. LYMPHADENITIS
• Lymphadenitis refers to inflammation of the lymph
nodes, typically due to infectious or immune causes.
• Can be acute or chronic based on the duration and
underlying pathology.

8. TYPES
1) Acute Lymphadenitis
• Etiology: Most commonly bacterial infections.
• Clinical Features:
• Sudden onset
• Painful, tender, and enlarged lymph nodes
• Skin over node may be red and warm
• May be associated with fever and systemic symptoms
• Examples:
• Streptococcal or staphylococcal infections in tonsils, skin,
or wounds

9. 2) Chronic Lymphadenitis
• Develops over weeks to months
• Less tender, firmer lymph nodes
• Common causes:
• Tuberculosis: caseating granulomas
• Cat-scratch disease: Bartonella henselae →
suppurative granulomas
• Fungal infections
• Toxoplasmosis

10. HISTOLOGICAL FEATURES
• Acute:
• Neutrophilic infiltration
• Follicular hyperplasia
• Edema and sinus dilation
• May show abscess formation
• Chronic:
• Granulomatous inflammation (e.g., TB: caseating
granulomas)
• Follicular hyperplasia (e.g., in viral infections)
• Paracortical hyperplasia (e.g., in immune responses)
• Sinus histiocytosis: prominent histiocytes in medullary
sinuses

11. LYMPHOID NEOPLASMS
• Lymphoid neoplasms are malignant proliferations
of lymphoid cells.
• They originate from clonal expansion of B cells, T
cells, or natural killer (NK) cells at various stages of
differentiation.

12. CLASSIFICATION
ymphoid neoplasms are broadly classified into:
• Non-Hodgkin Lymphoma (NHL)
• Diverse group of lymphomas involving B or T cells
• Variable behavior: indolent to highly aggressive
• Hodgkin Lymphoma (HL)
• Characterized by Reed–Sternberg cells
• Typically involves contiguous lymph node spread
• Other Lymphoid Malignancies
• Leukemias: Neoplastic lymphoid cells primarily involving blood and
bone marrow
• e.g., Acute Lymphoblastic Leukemia (ALL), Chronic
Lymphocytic Leukemia (CLL)
• Plasma cell neoplasms: e.g., Multiple Myeloma

13. ORIGIN
• Lymphoid neoplasms arise from:
• B-cell lineage (most common)
• T-cell lineage
• Natural Killer (NK) cell lineage
• Each type reflects the stage of maturation and
function of the cell of origin, leading to different
clinical features, morphology, and prognosis.

14. NON-HODGKIN LYMPHOMA
• A heterogeneous group of malignant lymphoid neoplasms.
• More common than Hodgkin lymphoma.
• Can arise in lymph nodes or extra nodal sites (e.g., GI tract,
skin, brain).

15. CLASSIFICATION
NHL is classified based on:
• Cell of origin:
• B-cell neoplasms (most common)
• T-cell and NK-cell neoplasms
• Grade of aggressiveness:
• Indolent (slow-growing): e.g., Follicular
lymphoma
• Aggressive: e.g., Diffuse large B-cell lymphoma
• Highly aggressive: e.g., Burkitt lymphoma

16. EXAMPLES
• Diffuse Large B-Cell Lymphoma (DLBCL)
• Most common NHL subtype
• Rapidly growing mass, often in older adults
• Potentially curable with chemotherapy
• Follicular Lymphoma
• Indolent, slow progression
• Originates from germinal center B cells
• Often presents with generalized lymphadenopathy
• Burkitt Lymphoma
• Highly aggressive
• Associated with EBV in endemic forms
• Common in children and young adults
• “Starry sky” appearance on histology

17. CLINICAL FEATURES
• Painless lymphadenopathy
• B symptoms: fever, weight loss, night sweats
(especially in aggressive types)
• Involvement of extranodal sites
• Variable prognosis depending on type and stage

18. HODGKIN LYMPHOMA
• A malignant lymphoma characterized by the presence of
Reed–Sternberg (RS) cells.
• RS cells are large, binucleated or multinucleated cells with
prominent nucleoli (“owl’s eye” appearance).

19. KEY FEATURES
• Bimodal age distribution:
• First peak: young adults (15–35 years)
• Second peak: older adults (>55 years)
• Contiguous spread from one lymph node group to
the next (predictable pattern)

20. • Nodular Sclerosis
• Most common subtype
• Collagen bands divide lymphoid tissue into nodules
• Common in young females
• Mixed Cellularity
• Second most common
• Numerous RS cells with a mixed inflammatory background
• More common in older adults
• Lymphocyte-Rich
• Many reactive lymphocytes, few RS cells
• Best prognosis among subtypes
• Lymphocyte-Depleted
• Few lymphocytes, many abnormal RS cells
• Worst prognosis
• More common in elderly or HIV-positive patients

21. PROGNOSIS
• Generally good prognosis with appropriate treatment
(chemotherapy ± radiotherapy)
• 5-year survival rates >85% in early-stage disease

22. COMPARISON – NHL VS HL
• NHL: Non-contiguous spread, B/T cells, All ages,
Variable prognosis.
• HL: Contiguous spread, Reed–Sternberg cells, Young
adults + elderly, Good prognosis.

23. METASTATIC CARCINOMA IN
LYMPH NODES
• Spread of cancer cells to lymph nodes from primary
site.
• Common sites: Lung, breast, stomach, colon
• Morphology: Enlarged, hard, fixed nodes
• Important for cancer staging and prognosis

24. SUMMARY
• Reviewed lymph node structure and functions.
• Discussed lymphadenopathy and lymphadenitis.
• Differentiated between NHL and HL.
• Metastasis to lymph nodes and clinical relevance.

25. REFERENCES
• Ramadas Nayak. Textbook of Pathology for Allied
Health Sciences.