lymphadenitis
Summary
Lymphadenitis is inflammation of a lymph node, usually producing tender enlargement. Acute lymphadenitis is most often a reactive response to drainage from a nearby infection, while chronic lymphadenitis reflects persistent antigenic stimulation.
Detail
Acute lymphadenitis produces nodes that are enlarged, tender, and mobile, with a swollen capsule; the commonest causes are pyogenic bacteria such as Staphylococcus aureus and Streptococcus pyogenes draining from a skin or pharyngeal focus. Suppurative nodes may soften and drain. Chronic lymphadenitis takes several histological patterns that map to different causes: follicular hyperplasia in rheumatoid arthritis, toxoplasmosis, and early HIV; paracortical hyperplasia in viral infections and after drug reactions such as phenytoin; and sinus histiocytosis in nodes draining a carcinoma. Granulomatous lymphadenitis suggests mycobacterial disease, cat-scratch disease from Bartonella henselae, or fungal infection. The key clinical discrimination is between reactive lymphadenitis, which is tender and mobile, and malignant lymphadenopathy, which is classically non-tender, firm, and fixed, with lymphoma additionally suggested by B symptoms.
Sources
- Robbins Basic Pathology
- First Aid for the USMLE Step 1
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