PA3.4 | Inflammation Morphology — Practical — Summary & Reflection

REFLECT

Look back at the four-panel image (Panel A–D) you studied earlier. Without re-reading the labels:

1. Can you name the pattern in each panel and identify at least two microscopic features that led you to that conclusion?
2. If a friend asked you 'what is the single most important cell to identify first on an inflammation slide?' — what would you say, and why?
3. Which pattern do you find hardest to distinguish from the others? Write one distinguishing feature you will use as your anchor.

KEY TAKEAWAYS

Core take-home points for PA3.4:

• Cell type is the master key: neutrophils = acute; lymphocytes + plasma cells + macrophages = chronic; epithelioid histiocyte clusters = granulomatous.

• Acute patterns: suppurative/abscess (pus, liquefactive necrosis), fibrinous (fibrin strands, 'bread-and-butter' pericarditis), serous (dilute exudate), ulcer (four zones), phlegmon (diffuse spreading).

• Chronic: mononuclear infiltrate + fibrosis ± granulation tissue; 'active chronic' = neutrophils on top of a mononuclear background.

• Granuloma: epithelioid histiocytes + Langhans giant cells (peripheral horseshoe nuclei) + lymphocyte cuff ± caseation (TB) / non-caseating (sarcoid/foreign body).

• Gross correlates: abscess (creamy cavity), fibrinous pericarditis (bread-and-butter), chronic peptic ulcer (punched-out, indurated), granulomatous node (grey-white foci ± softening).

• Reading strategy: low → high power; dominant cell first; name pattern; note special features (caseation, giant cell nuclear arrangement, fibrosis).