Lymphadenopathy
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Direct answer
Lymphadenopathy is read through site, duration, consistency and systemic features, and in India the differential is dominated by tuberculosis — the commonest cause of chronic lymphadenitis — followed by reactive hyperplasia, metastatic carcinoma and lymphoma. Histology sorts reactive patterns into follicular (B-cell driven, as in rheumatoid disease or HIV), paracortical (T-cell and viral) and sinus variants, while granulomatous inflammation splits on caseation: caseating epithelioid granulomas with Langhans giants point to tuberculosis, non-caseating ones to sarcoidosis. Fine-needle aspiration cytology is the standard first test in Indian practice, with excision biopsy reserved for suspected lymphoma, where nodal architecture is the diagnosis.
What you must remember
- Reactive patterns: follicular hyperplasia (rheumatoid arthritis, HIV, toxoplasmosis), paracortical expansion (viruses, drug reactions), sinus histiocytosis — the pattern predicts the trigger.
- Tuberculous lymphadenitis: cervical nodes most often; caseating granulomas with Langhans giant cells and lymphoid depletion in advanced disease; AFB stain and cartridge-based nucleic acid testing confirm.
- Caseation is the divider: caseation favours tuberculosis, non-caseating granulomas with asteroid and Schaumann bodies favour sarcoidosis.
- Cat-scratch disease: suppurative, stellate granulomas with Warthin-Starry-positive Bartonella henselae, axillary or epitrochlear nodes after a kitten scratch.
- Kikuchi-Fujimoto disease: young women, painful cervical nodes, necrotising histiocytic change without neutrophils — famous mimic of lymphoma and lupus.
- Metastatic mechanics: carcinoma first colonises the subcapsular sinus; a hard left supraclavicular node (Virchow's node) signals gastric or other abdominal carcinoma; signet-ring cells name stomach origin.
- Lymphoma discipline: FNAC may sample lymphoma but cannot reliably classify it — excision biopsy preserving architecture is required, a rule repeatedly tested.
A cervical node in a young woman, worked through
A 26-year-old has a month of low-grade fever and a matted right cervical node cluster. Aspiration cytology shows epithelioid granulomas with central caseous necrosis; cartridge-based molecular testing detects Mycobacterium tuberculosis, and antitubercular therapy begins with the node expected to regress over months. Had the aspirate shown non-caseating granulomas, the pathway would pivot to sarcoidosis — chest imaging for hilar nodes and serum angiotensin-converting enzyme. Had the node been painless, rubbery and progressive over months with weight loss, lymphoma moves up, and the correct next step becomes excision biopsy, not more aspirates, because subtype assignment depends on architecture and immunohistochemistry of the intact node. One clinical presentation, three branching pathways, each hinging on a specific histological or molecular finding — this is the reasoning FMGE vignettes are built from.
Where students slip
Site associations are half-memorised: posterior auricular nodes suggest rubella, occipital nodes scalp infection, left supraclavicular nodes abdominal malignancy — candidates blur these classic pairs. The word "caseation" is used loosely; calling a sarcoid granuloma caseating collapses the entire differential. And the commonest practical error in Indian settings is treating every tuberculin-positive node as tuberculosis without aspirate confirmation, when lymphoma and metastasis can coexist with a positive test; the discipline of tissue before treatment is the actual lesson of this chapter.
Frequently asked questions
What is the commonest cause of chronic lymphadenitis in India?
Tuberculous lymphadenitis, typically cervical, confirmed by caseating granulomas and AFB or molecular testing on aspirated material.
How does sarcoid granuloma differ from tuberculous?
Sarcoid granulomas are non-caseating with asteroid and Schaumann bodies, while tuberculosis shows caseous necrosis with Langhans giant cells.
What is Virchow's node?
A hard left supraclavicular node receiving thoracic duct lymph, classically signalling gastric carcinoma and other abdominal malignancies.
Why is excision biopsy preferred for suspected lymphoma?
Lymphoma classification depends on architecture and immunophenotype, which aspiration cytology cannot assess reliably.
Which organism causes cat-scratch disease and how is it shown?
Bartonella henselae, demonstrated by Warthin-Starry silver stain in suppurative stellate granulomas.