Lymphadenopathy pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]
Overview
Lymph nodes are part of the immune system. As such, they are most readily palpable when fighting infections. Infections can either originate from the organs that they drain or primarily within the lymph node itself, referred to as lymphadenitis.
Pathophysiology
Lymph nodes are part of the immune system. As such, they are most readily palpable when fighting infections. Infections can either originate from the organs that they drain or primarily within the lymph node itself, referred to as lymphadenitis.*The pathogenesis of lymphadenopathy is characterized by the inflammation of lymph nodes. This process is primarily due to an elevated rate of trafficking of lymphocytes into the node from the blood, exceeding the rate of outflow from the node.[1]
- The immune response between the antigen and lymphocyte that leads to cellular proliferation and enlargement of the lymph nodes.
- Lymph nodes may also be enlarged secondarily as a result of the activation and proliferation of antigen-specific T and B cells (clonal expansion).
- On gross pathology, characteristic findings of lymphadenopathy, include:
- Enlarged lymph node
- Soft greasy yellow areas within the capsule
Microscopic findings
- On microscopic histopathological analysis, characteristic findings of lymphadenopathy will depend on the etiology.Common findings, include:[1]
Non-specific reactive follicular hyperplasia (NSRFH)
- Large spaced cortical follicles
- Tingible body macrophages, normal dark/light GC pattern
Lymph node metastasis
- Foreign cell population (usually in subcapsular sinuses)
- +/-nuclear atypia
- +/-malignant architecture
Toxoplasmosis
- Large follicles
- Epithelioid cells perifollicular & intrafollicular
- Reactive GCs
- Monocytoid cell clusters
Cat-scratch disease
- PMNs in necrotic area
- "Stellate" (or serpentine) shaped micro-abscesses
- Presence of granulomas
Dermatopathic lymphadenopathy
- Melanin-laden histiocytes
- Histiocytosis
Systemic lupus erythematosus lymphadenopathy
- Blue hematoxylin bodies
- Necrosis
- No PMNs