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PA19.1-6 | Welcome to Tuberculous Lymphadenitis — Pathology & Specimen
Learning Objectives
- Explain the immunopathogenesis of tuberculous lymphadenitis as a Type IV hypersensitivity response, tracing the role of CD4 Th1 cells, IFN-γ, and macrophage activation
- Describe the structure and evolution of the tuberculous granuloma, identifying its cellular components and the significance of caseous necrosis
- Recognise the gross features of scrofula — matted cervical lymph nodes, caseous (cheesy) material, cold abscess formation, and sinus tracts
- Identify and interpret the microscopic features of caseating epithelioid granulomas and Langhans giant cells in histological sections
- Demonstrate knowledge of Ziehl-Neelsen staining for acid-fast bacilli and the approach to confirming the diagnosis (FNAC, biopsy, GeneXpert)
- Construct a differential diagnosis of granulomatous lymphadenitis, distinguishing tuberculous from non-caseating and other infectious granulomas
INSTRUCTIONS
Tuberculosis lymphadenitis (scrofula) is the single commonest form of extrapulmonary TB you will encounter in clinical practice. In India, it accounts for up to 35% of peripheral lymphadenopathy referrals. More importantly, it is the paradigm lesion for understanding granulomatous inflammation — a pattern that recurs across Pathology, Medicine, and Surgery. Mastering the morphology here gives you the cognitive template for sarcoidosis, leprosy, Crohn disease, and fungal infections. This module is also practical: two of your CBME skill competencies (PA19.2 and PA19.5) require you to examine a gross node or glass slide and narrate what you see. Work through every specimen checkpoint; your ability to do this in an OSCE depends on the vocabulary you build today.
References
- Robbins & Cotran Pathologic Basis of Disease, 10th ed., Ch. 8 (Infectious Diseases) & Ch. 13 (Lymph Nodes) (textbook)
- Harsh Mohan — Textbook of Pathology, 7th ed., Ch. 6 (Inflammation) & Ch. 30 (Lymph Nodes) (textbook)
- Dail & Hammar's Pulmonary Pathology, Vol. 1, Ch. 11 (Mycobacterial Infections) — for granuloma evolution (textbook)
Version 2.0 | NMC CBUC 2024